Home

Final Design Report

1. MI E 15 E Ba EA ga gin uz o LE wi m nac 7 c 0 E LUN Le in L 5 ju W 2 4 iz E a ar 4 AR WITH CF 2115 Ag HERE STEM AMO PR paz ARE ASSEMBLED HERE CREATE 4 25 La SPRING LEF STAGED HERE GCO ASSEWELY WP ETAEED HERE COLLAR 15 DCD BSR CREATE THE FIHBHEO OCD ASSEMBLY FIMBHED PROQUCTIS STAGED HERE OCD COLLAR cocEDHERE Figure 3 0 1 Production Floor Plan Layout from SW Resources 13 3 1 Revised Needs Statement SW Resources employees with varying levels of disability need a device to assist with handling and installing O rings We are targeting our design towards employees with less severe disabilities to improve their productivity In order to meet SW Resources production goal of 30 000 parts assembled per day a total of 80 SW Resources employees must be able to use our design to install a total of 90 000 O rings per day 9 3 2 Target Specifications SW Resources employe
2. LA JUNO 19 19 22 23 25 27 30 30 33 36 42 45 54 54 61 63 9 0 Concept Screening and Evaluation 9 1 Design Description and Operation 9 1 1 Large O ring Fixture 9 1 2 Medium O ring Fixture 9 1 3 Small O ring Fixture 9 2 Cost Estimation and Manufacturing and Assembly Processes 9 2 1 Large O ring Fixture 9 2 2 Medium O ring Fixture 9 2 3 Small O ring Fixture 9 3 Design Drawings Parts List and Bill of Materials 9 3 1 Large O ring Fixture 9 3 2 Medium O ring Fixture 9 3 3 Small O ring Fixture 10 0 Conclusions References Appendix A Data on Disabilities in the United States Appendix B Customer Observation Notes Appendix C FMEA Worksheets Appendix D Customer Prototype Evaluation Forms Appendix E User Manual Appendix F Part and Assembly Engineering Drawings 65 65 66 67 66 69 69 70 71 73 73 74 76 76 79 91 95 97 96 97 111 1 0 Introduction A disability is defined as a disadvantage or deficiency especially a physical or mental impairment that interferes with or prevents normal achievement 1 According to this definition normal achievement includes entering or progressing in the work force According to 2006 data from the American Community Survey published by the U S Census Bureau over 15 1 of the U S population who are five years or older have at least one disability In the age range of 16 64 years old nearly 24 million persons have
3. Figure 6 1 5 Design Concept for Large O ring Fixture 7 0 Prototype Design Development and Testing 7 1 Failure Mode and Effects Analysis In order to develop a robust design we made use of the Failure Mode and Effect Analysis FMEA to identify major potential failure modes and hazards for the systems we were designing and to incorporate features into our designs to minimize the risk of failure or hazards as much as possible In order to ensure that our design met our specifications we developed some empirical tests for our designs focusing particularly on the failure modes which have either a higher risk of occurrence or a greater severity FMEA is an important tool for design engineers because it is an engineering technique used to define identify and eliminate known and or potential failures problems errors from the system design process and or service before they reach the customer 14 The power of this method is that when used effectively and correctly it provide s the practitioner with useful information that can reduce the risk work load in the system design process and service 14 It is extremely useful as a preventive tool The method we employed was to rate each failure mode based upon three component factors the severity of the failure the likelihood of its occurrence and the probability of detection We 30 obtained numerical estimates of each of these factors by giving each one a rating o
4. 1 4 Customer Selection The company to be assisted is SW Industries a branch of SW Resources located in Parkersburg West Virginia They provide services to the business community through the talents of individuals with disabilities in the Mid Ohio Valley Many of these services are packaging shipping or light assembly projects that some businesses find tedious and it 15 one of these light assembly projects that will be looked at for better alternatives SW Industries the largest division of SW Resources 2 and the division which contracts with state and federal governments as well as local and national businesses 3 is the division of SW Resources that we are specifically working with for our project As mentioned in the introduction the percentage of the population with disabilities is unusually high in West Virginia so we are providing a service for a geographic area where the need for assistive technology is arguably the greatest 2 0 Customer Needs Assessment It is very important to find out as much about SW Resources as possible so that we could accurately and completely assess the specific needs of our customer and the persons employed by our customer Our project is to develop a product that is satisfactory to our customer therefore our initial goal was to accurately identify the customer s specific needs The measure of our success for this design project is how well SW Resources decides our project fits the needs of its emp
5. 5 SHA VA TA d 4 2 SY 27 PUR Figure 4 3 1 O Ring Insertion This patent is for the installation of O rings into female seal grooves located internally of a bored cylinder This device is based off of a medical syringe with some modifications Figure shows the O ring 6 being placed within the syringe In Figure 2 the O ring is still inside the syringe and the syringe has been placed within the bored cylinder 8 In Figure 4 the plunger 2 has been depressed and the O ring is being placed within the desired groove 9 Lastly in Figure 5 the plunger has been completely depressed and the O ring is entirely in the groove and the syringe is ready for removal While this device is for internal O rings and the project being focused on is for external O rings our group can learn from this design The first thing is that it gives another method for using a press Rather than being stuck on the idea of some sort of arbor press this syringe provides a simpler and cheaper way to get the same motion desired from an arbor press without the unnecessary costs and without the overpowering force that an arbor press provides Another great aspect of this device is the size If this device could be altered in order to be applied to the QCD Encore than it would be a huge space saver 14 Patent 2 Face Seal O ring Insertion Tool 8 Patent number 6012209 Filing date Jul 8 1998 Issue
6. 7 Repeat steps 1 through 6 3 3 Suggested Maintenance Schedule and Instructions Periodically the rubber layer will wear out and will need to be replaced The following procedure describes how the rubber layer should be replaced 1 Completely loosen the screws which hold the front cover 2 Remove the front cover from the device 3 Slide the rubber layer out of the pocket 4 Slide the new rubber layer into the pocket 5 Replace the cover and tighten the screws which hold the cover We recommend replacing the rubber layer every three 3 months or as needed Extended use of the device will mean the rubber layer will need to be replaced more frequently Since this device is designed to assist with installation of o rings for use in a food related use the device should be cleaned daily to ensure that it meets sanitation requirements To clean device either spray it with disinfectant or wash it with soap and water in a sink The device does not need to be disassembled for the sanitation procedure After the device is washed dry the hole in the device to ensure that no water is left sitting in the hole 3 4 Troubleshooting and Service Instructions If this device does not correctly install o rings replace the rubber layer 3 5 Replacement Parts Information Small O Ring Fixture Parts List Rubber Sheet E 125 Natural Latex 109 CL 20 The rubber sheet is the only part of the fixture that will need to be replaced
7. would be needed for easy o ring placement For the final design a set guide was manufactured from HDPE and placed on a spring that returns the set guide back to its original location once a part is finished The manufacturing procedure followed for the manufacture of the small O ring fixture also employed the use of numerous mock ups Mock ups were used to test various design features before these features were actually added to the prototype The small O ring fixture prototype was manufactured in the same manner as described later this report for the final design manufacturing process However when this prototype was constructed the manufacturing process was not completed in a perfectly systematic manner The plastic base was cut with a band saw and the top surface milled out to provide for the pocket and walls The top cover was milled out of some of the excess plastic and glued onto the base The surface of the base was 53 then further milled down to obtain a uniform surface The holes for the rubber feet were drilled out and the feet installed Then the rubber was cut sanded down so that it fit in the pocket and installed into the pocket in the base Finally a slope was milled out of the top surface 7 5 Prototype Testing The primary objective of our prototype testing was to determine and measure the ease of use of the three fixtures we designed In addition we also tested our prototypes to determine productivity rates associated w
8. 8 Strain von Mises in in 0 1247867 0 1124138 0 1000408 0 0876679 0 07529496 0 06292202 0 05054909 0 03817615 0 02580321 0 01343027 0 001057334 16 15 Time Step 20 of 20 Maxirnum Value 0 124787 in in 0 000 0 589 in 1 178 1 767 Minirnum Value 0 00105733 in in Figure 7 3 3 8 Location of Maximum Strain 52 Because the maximum stress value was less than the 319 1 psi fatigue strength for 1 5 million cycles we have concluded based on our FEA results that the rubber layer meets the requirement that its lifetime not be less than one year In the case that the rubber sheet fails before one year we have designed the rubber sheet with two holes Thus the user can take the rubber sheet out of the slot flip the rubber sheet over and insert the rubber back in so that the second hole is used Thus we have minimized material cost by utilizing more of the material 7 4 Prototype Manufacturing Each prototype was manufactured independently Since we used HDPE for most of the prototype material we used a CNC mill for precise manufacturing of the prototypes For the large O ring fixture the prototype manufacturing followed the procedure described later in this report for the final design manufacturing For the medium o ring device the prototype was manufactured using scraps of pine wood The base feature was made from wood Sides were built on top of the base making the base hollow inside Initially we experimented wit
9. 8300 psi Also we added an HDPE rail around the perimeter of the tray not included in FEA that will further help absorb an impact The figures below show the loading of the tray and the point of maximum stress To find the impact force conservation of energy and the impulse momentum equations were used The force of impact was found to be 24 5 pounds mass withstand a four foot fall Setting the input force to be 30 pounds we found the maximum stress Once this force was found it was used in FEA of the tray to determine whether the tray will converged to a value of approximately 206 psi 4 40 Figure 7 3 1 6 FEA Setup for Bending in Feed Tray of Large O ring Fixture 4 Figure 7 3 1 7 FEA Stress Concentration Result for Large O Ring Fixture 7 3 2 FEA for Medium O ring Fixture For the drop test we used static stress with linear material models The element definition was von Mises with Isotropic Hardening and the material selected was HDPE Injection Molded The properties as follows Table 7 3 2 1 Material Property for HDPE Base Modulus of Elasticity 118 000 psi Yield Strength 3000 psi Shear Modulus of Elasticity 43 066 psi Table 7 3 2 2 HDPE Base Stress Results Mesh Size in Max Stress psi Displacement in 05 0 0035 2 local Refine 0 0125 640 39 0 0025 3 local Refine 0 0625 635 17 0 0023 By applying the Impulse Momentum Theory equation the average impact force applie
10. BS an 1 SPL es REVISION HIS TORY son ws SOLID EDGE p 095 The PLM Company ENG a Stainless MER Ap 1 2 UNLESS UO TL HEBWISE SHECIFIED D MERSIOKS ARE IN INCHES ANGLES 0 P 2 1023 0010 SHEET QF 117 MATERIAL LEAH SOLID EDGE Pt HERI ELE LI ss 118 lam mx n 15 5001 Bee ______ 5 5 009 ani c al 11 21 gt PL 119 All round 0125 in Matar ial HDPE d T Er 120 br 1 0104 zas pec qe TUE SUOS 121 00 5 51 or Egana 1562 15 eri 122 3 Geer Al Sera l Sa E coo 551 KOLO TEL TILE L a ea 123
11. a maximum displacement of 0 0023 inches Figure 1 3 2 1 Mesh and Constraints 43 Stress von Mises Ibf in 2 700 630 560 490 420 350 280 210 140 70 0 Load Case 1 of 1 Maximum Value 664 798 Ibf in 2 FAN 4820 7220 Minimum Value 0 0590129 Ibf in 2 Figure 7 3 2 2 von Mises Stress Displacement Magnitude in 0 004 0 0036 0 0032 0 0028 0 0024 0 002 0 0016 0 0012 0 0008 0 0004 0 Load Case 1 of 1 Maximum Value 0 00349112 in dO 2654 in 5307 7 981 Minimum Value 0 in Figure 7 3 2 3 Displacement 44 Due to size and short drop distance the maximum stress 1s not all that important to us What is important is the maximum deflection We wanted to be sure that small deformation would occur if this was dropped Assuming worst case scenario that 18 if impact occurs where the surface area 18 smallest 1 e the edge corners deflection would be maximum From the FEA analysis a maximum deflection of 0 0035 inches isn t much of a concern and normal operation will continue 7 3 3 FEA for Small O ring Fixture There were two failure modes for the small O ring fixture that we investigated using finite element analysis The first scenario was a drop test a simulation of the fixture being dropped from its normal height on a table during operation and hitting the floor As with the other two fixtures we were concerned that if the user accidentally dropped the fixture the fixture m
12. all three designs The following discussion relates to this analysis It was important for the elastic bands in the fixture to be able to withstand the input force of the part into the fixture The required input force to push the part through the bars was found to be 60 Newtons using a digital force gauge The elastic band was modeled in SolidEdge and cut into of the original size to benefit from symmetry Figure 7 3 1 33 0 000 0 175 in 0 349 0 524 NUM Figure 7 3 1 Elastic Band FEA Mesh The following was done to simulate the tensile force applied to the elastic band 6 7 lbf was applied to the curved surface in the negative X direction Cut surfaces were fixed in their respective directions due to the effect of symmetry Material selection Rubber Element Definition Mooney Rivlin A nonlinear analysis was run three times decreasing in mesh size each time to find the von Mises stress in the elastic band The results were compared the material being used in the fixture Table 7 3 1 Material Properties of O Ring Table 7 3 2 Elastic Band Stress Results Mesh Size in Max Strain in in Max Stress psi Displacement in 0278 464 02 0 025 0 400 433 5 34 After 3 tests the maximum stress value converged to within 2 8 A stress of 421 3 psi is well below the yield strength 2 150 psi of the Buna N rubber and verifies that the elastic band will not fail while pushing the par
13. cleaning solvents to de sanitize the device User Friendly Will the device be simple enough for workers with less severe disabilities to operate Cost Which concept would cost less to develop Could the concepts be developed under 500 24 Maintenance Will the device have low maintenance If utilizing moveable parts will they have a low failure rate Size Will device be versatile Will there be enough room for many of these to be placed on a 8x4ft table Could the workers fit device in wash sink for sanitary purposes 6 0 Final Concept Selection After carefully examining the four concepts the team agreed that concepts one two and four are the final candidates Concepts one and two will be used for installing the O ring onto the QCD body and plug We will be developing a parallel design development for these two concepts because we have decided that we need further data to determine which concept 1s the better design By developing these two concepts in parallel we will be able to test the prototypes and directly compare how well they perform the desired task of applying the O rings These concepts are very similar operation requiring that the employee places the part within a jig Figure 6 0 1 shows a diagram of concept one Notice that this design is easily manufactured and very simple to use It consists of a spring loaded stop to guide the part into the hole The O ring will be held in place with an inner edge on the inside of
14. desired time and load on an S N curve for rubber 5 Notes on Completed Actions We have designed the small o ring fixture so that the rubber layer can be replaced easily and simply were the rubber layer to fail due to fatigue However 90 Potential Failure 4 Material wear corrosion due to cleaning Operating mode when failure could occur Potential Failure Mode Setup operation transportation cleaning Initial After Action B 7 Potential Mechanism s of Failure p L 1 of occurrence OCC Current Le or Bou Ross for Detection and Prevention Probability that failure is detected and prevented DET Risk Priority Number RPN SEV OCC DET 1 3 20 1 Include some discussion justification for the rating for severity SEV If the rubber corrodes than the fixture 18 no longer useful and the rubber must be replaced While Potential E Potential Effect of Failure Severity SEV of Failure Severity SEV there are no safety issues here it does render the fixture useless which 1s unacceptable 2 Include some discussion justification for the rating for probability of occurrence OCC The Buna N rubber is FDA approved for corrosion resistance 3 Include some discussion justification for the rating for probability of detection DET Not necessary 4 Recommended actions to achieve acceptable risk Make specific recommendations for action and include so
15. features needed to be added to the devices in order for the customer to actually use the devices We recommend that any future action taken for this project define more accurately and precisely the customer s actual needs and develop design concepts more conformable to those customer needs Table of Contents 1 0 Introduction 1 1 Project Definition 1 2 Project Scope and Goals 1 3 Initial Needs Statement 1 4 Customer Selection 2 0 Customer Needs Assessment 2 1 Customer Project Selection 2 2 Customer Needs Identification 2 3 Weighting of Customer Needs 3 0 Revised Needs Statement and Target Specifications 3 1 Revised Needs Statement 3 2 Target Specifications 4 0 External Search 4 1 Problem Clarification 4 2 Benchmarking 4 2 Applicable Patents 4 3 Concept Generation 5 0 Concept Screening and Evaluation 5 1 Data and Calculations for Feasibility and Effectiveness Analysis 5 2 Concept Screening 5 3 Concept Development Scoring and Selection 6 0 Final Concept Selection 6 1 Final Concept Diversification 7 0 Prototype Design Development and Testing 7 1 Failure Mode and Effect Analysis 7 2 Prototype Material Selection 7 3 Design Analysis 7 3 1 FEA for Large O ring Fixture 7 3 2 FEA for Medium O ring Fixture 7 3 3 FEA for Large O ring Fixture 7 4 Prototype Manufacturing 7 5 Prototype Testing 7 5 1 Input Force Measurements 7 5 2 Time Trials 8 0 Design Refinement for Production Fe 120 Un MARAL
16. first 2 Or check to see that the tray cutout for the o ring is relatively centered on the two rods and the neck of the platform 1 5 Replacement Parts Information 100 101 Part Part Material Vendor Number 1 Lexan amp HDPE McMaster rails Carr Athens Glass 8 32 x 1 Hex Lowes Bolt 5 B 8 Rod Holder HDPE McMaster 8 Base Screws 1 coarse thread Lowes screws HDPE McMaster Carr 1 Long Screw 2 in machine Lowes screw amp nut 102 Chapter 2 Medium O ring Fixture Body 2 1 Warnings and Safety Precautions WARNING Dropping fixture from large height s may result in damage to the fixture A WARNING Do not place fingers in hole in top cover 2 2 Operating Instructions 6 Place o rings on top cover to be assembled 103 7 Place 1 o ring over guide 8 Place the part vertical orientation on top of the o ring and push down on the part until it travels through the rods securing the o ring on the part 9 Pull part out 10 Repeat steps 1 4 for desired part quota 2 3 Suggested Maintenance Schedule and Instructions A Replacing the rubber bands 5 Use 5 32 Allen Key wrench to loosen the bolts 4 and remove the top cover 6 Remove rods 2 from base 7 Remove rubber bands from rods 8 Install new rubber bands on rods and assemble fixture 104 2 4 Troubleshooting and Service Instructions If the fixture 18 not functioning pro
17. per O ring Input force 4 0 External Search In order to generate design concepts that were relevant to our selected tasks and that met general regulations and requirements we performed several broad searches of applicable patents a literature search of O ring installation and government and industry standards and constraints 4 1 Problem Clarification The installation of the O rings contains three major obstacles due to the three different O ring sizes The design required will need to be applicable for all three parts However since each of three O rings have unique features we considered the possibility that three unique designs one unique design for each O ring may need to be pursued We determined that at most two unique 10 designs would be needed After developing initial ideas it was a team decision to develop multiple designs suitable for each O ring The design required will support the task of taking a loose O ring and placing the ring into its slot on the respective part The design will have to be very simplistic to accommodate the wide varieties of mental and physical handicaps The task is currently performed all by hand which is meticulous and labor intensive In order to label each part they will be defined as the base part tip part and stem part shown in Figures 4 1 1 4 1 2 and 4 1 3 respectively Figure 4 1 1 Base Part Figure 4 1 3 Stem Part 4 2 Benchmarking 11 When beginning to generate idea
18. program at the Russ College of Engineering and Technology at Ohio University This capstone design project is a year long team project for students majoring 1n mechanical engineering at Ohio University The senior capstone design project sequence for the year 2008 09 is focusing on the NISH National Scholar Award Workplace Innovation amp Design competition and the design teams are expected to compete in the 2009 NISH competition This competition focuses on designing creative technological solutions to barriers that prevent people with disabilities from entering or advancing in the workplace 10 For this project student design teams are encouraged to work with nonprofit agencies NPAs who employ persons with disabilities particularly those NPAs which are affiliated with NISH There are seven distinct topic areas which NISH seeks to address through this competition The seven areas are listed here taken directly from the NISH competition description 10 1 Technology for Special Populations cognitive disabilities learning disabilities developmental disabilities low vision blindness hearing impairments dysphasia elderly interventions service delivery programs 2 Augmentative and Alternative Communication communication boards computer based communication devices 3 Computer Access and Use innovation in software and hardware training Strategies integration of computer technologies alternative access 4 Environme
19. referred to as the nozzle housing or medium part The part has a tapered head which assists in helping the o ring roll into place The base utilizes two stainless steel rods held in tension by two elastic bands As the housing 18 pressed downward through the rods the o ring 1s forced to slip around the tapered head of the part as the rods apply pressure on the part below the o ring Refer to the User s Manual for proper operating instructions and safety precautions 67 The design drawings for these components can be found in Appendix F Number 1 is the base Number 2 is the o ring tray Number 3 is the o ring set guide Number 4 represents the stainless rods Number 5 18 the return spring for set guide The user slides an o ring from the tray to the set guide where it is placed over top The user takes a housing part and presses it head first onto the set guide until the part will not press any further down This is enough to install the o ring The user the pulls the part back up and places the finished part into a parts bin 9 1 3 Small O ring Fixture Part for O ring Installation Screws Front Cover Figure 9 1 1 Small O ring Fixture Final Design The final design for the small o ring fixture consists of five different parts as seen in Figure 9 1 1 The base top cover front cover rubber and two screws The fixture operates in two quick steps The first step is to slide an o ring into the hole of the top cover locat
20. still wet or slippery 3 Include some discussion justification for the rating for probability of detection DET Whether or not the device failed due to this mode would be easy to verify for any user even those with severe physical and moderate mental disabilities 4 Recommended actions to achieve acceptable risk Make specific recommendations for action and include some discussion of the alternatives that were considered the person s responsible for completing the actions and the completion date We will investigate the robustness of these designs using FEA to simulate this design failure We also verified this test physically when we accidentally dropped one of these devices during transportation 5 Notes on Completed Actions The FEA results indicate that it is not likely that this failure mode will occur The HDPE base 1s strong enough to resist this type of failure 95 Appendix D Customer Prototype Evaluation Form CUSTOMER PROTOTYPE EVALUATION FORM STEM O RING FIXTURE Mechanical Masters Department of Mechanical Engineering Ohio University Circle one for each 1 Strongly Disagree 2 Disagree 3 Neutral 4 Agree 5 Strongly Agree User Friendly 1 2 3 4 5 Sufficient Size 1 2 3 4 5 Operates Consistently 1 2 3 4 5 Increases Productivity 1 2 3 4 5 Safe for Employees 1 2 3 4 5 Easy to Clean 1 2 3 4 5 Overall does this design adequately meet your needs Explain Specitically what were the problem
21. the hole This ledge will be made at a diameter slightly smaller than the diameter of the O ring forcing the O ring to slide into its seat Figure 6 0 1 Concept one uses a spring and cap to guide part Concept two is slightly different in the way that the O ring is held As in the first concept a hole will be bored into a plastic base Rather than machining a ledge this concept utilizes an elastomer to hold the O ring Figure 6 0 2 This material will be placed between the plastic base and a stainless steel top held together with four hand tighten screws A hole will be cut with a smaller diameter than the O ring directly above the hole in the base This allows for the part to be forced downward until the O ring slips into its seat 25 Figure 6 0 2 Concept Two using rubber to hold O rings Concept four was chosen to install the O ring onto the dispenser shaft The shaft introduces geometries that will not work with concepts one or two This concept will use a spring loaded tool head to place the seal onto the part placed into a specially designed holder The chamfered head would stretch the O ring forcing it to roll downward over the head into its seat This design will be slightly more complex because the geometry of the part requires that the O ring must be initially stretched Before manufacturing the prototypes the concepts will be introduced to SW Resources Any new ideas will be applied and the concept testing w
22. the moving parts Potential failure modes for concept one e Bracket does not support the rods e Pins holding lever arm shear Lever arm bending after prolonged use 63 e Many pinch points e Spring failure at the end of rods All of these failure modes were given a severity of 9 as any of these failures will cause catastrophic failure and a probability of occurrence of a 7 since the number of moving parts and everyday use will cause parts to wear at a faster rate Safety was also a major concern with this concept too many pinch points and sharp edges The final concept was selected as we determined that it would be safer more reliable durable and easier to use This device is comprised of four basic components see Figure 9 1 1 1 later in this report platform and part holder base stainless steel rods rubber bands and a Lexan tray The base design is the main component of the system Manufactured from HDPE the base s functions include guiding the platform holding the steel rods and supporting the tray The pockets within the base were machined using Master Cam and CNC The angled section holding the rods was machined separately and mounted to the base using four 8 32 hex cap screws and brass inserts glued into the base The platform and part holder were manufactured as two separate parts They are bolted together using a three inch long 10 32 screw that extends to the bottom of the platform and held with a lock washe
23. 0 Q LL Time s Figure 7 5 1 5 Force vs Time Profile for Medium Fixture This force time profile shows that there are three distinct profiles 1 as the metal rods are pushed outward as the part is pressed into the o ring 2 the maximum force occurs right before the o ring rolls onto the part and 3 as the part 1s extracted from the fixture The maximum input force required 18 the value we are most concerned with The following table summarizes the results for the maximum force applied 59 Table 6 Final Results for Medium Fixture Input Force Testing 1 Wrap of Rubber Band These results show that the average maximum force is 13 4 Ibsf less than our target value of 15 Ibsf This maximum force occurs the instant before the o ring is installed onto the part For the small o ring Table 7 5 1 4 shows the maximum force was determined to be 16 8 pounds An average over 10 trials 18 11 7 pounds Using one s fingers to grip a small part causes discomfort after an extend period of time 2 Table 7 5 1 4 Small O ring Force Data Input Force Testing O 0 so oof This input force exceeds the required input force maximum requirement of 11 Ibsf We determined that the chief cause for this excessive force was the rubber layer Thus we decided 60 that we needed to select a different rubber material which had a greater flexibility instead of the current rubber material we used We replaced th
24. 004 4 Using an adhesive glue glue the top cover T5 S 004 to the base as seen in the assembly drawing 5 Mill out the top face of the base T5 S 001 and top cover T5 S 004 giving a smooth surface finish where the top cover and the base parts meet 6 Continue all other parts as seen in their respective drawings 12 7 Assemble all parts based on assembly drawing 9 3 Design Drawings Parts List and Bill of Materials Design Drawings for all three fixtures are located in Appendix The Parts List and Bills of Materials are given for each o ee fixtures in the following sections 9 3 1 Large O ring Fixture Figure 9 3 1 1 and Table 9 3 1 1 give the parts list for the Large O ring Fixture j 7 14 Figure 9 3 1 1 Large O ring Fixture 73 Table 9 3 1 1 Parts List for Large O ring Fixture Part Part Material Vendor Number Lexan amp HDPE McMaster Athens Glass rails Carr Athens Glass 8 32 x 1 Hex Lowes Bolt 5 1 4 216 SS 316 SS McMaster Carr 8 rods Rod Holder HDPE 7 se Screws 1 coarse thread Lowes screws Ba HDPE 9 Pafm HDPE Stem Holder HDPE 11 Long Screw 2 Lowes screw amp nut 9 3 2 Medium O ring Fixture Figure 9 3 2 1 and Table 9 3 2 1 give the parts list for the Medium O ring fixture 74 Figure 9 3 2 1 Medium O ring Fixture Table 9 3 2 1 Parts List for Medium O ring Fixture No Base 1 HPPE 771 Screws 4 10 24 g
25. 4 Recommended actions to achieve acceptable risk Make specific recommendations for action and include some discussion of the alternatives that were considered the person s responsible for completing the actions and the completion date Round all edges and keep pinch points to a minimum This is not much of a problem due to the simplicity of the design for the small and medium o rings 5 Notes on Completed Actions After prototype construction all edges were rounded Thus we had no sharp corners or edges in our fixtures that would endanger the users Potential Failure 6 Bending in metal o ring feed tray Operating mode when failure could occur Potential Failure Mode Operation storage setup transportation Bending and deflection of the metal Initial After Action Evaluation Results Potential Effect of Failure Severity SEV po ccc cleaning Potential Cause s Mechanism s of Failure 7 of occurrence OCC Current L e ok hr Bars Ress for Detection and Prevention that failure is detected and prevented DET 5 sx Toss Nose CDEN Priority Number RPN SEV OCC DET 1 Include some discussion justification for the rating severity If the tray 15 bent out of shape then feeding the o rings onto the fixture will perhaps be more difficult but this is not critical to the design Of more concern would be bending in the legs which support the tray If the l
26. 404 S Tenesee 174 403 9 Lousina 169 4 04 13 1151 0 77 13 Mexico 15 UmiedStats _ 13 01 62 Table A2 EMPLOYMENT STATUS OF CIVILIAN NONINSTITUTIONALIZED POPULATION 16 TO 64 YEARS OLD WITH A DISABILITY 4 EMPLOYMENT Margin of Margin of Margin of 227 1610 193 568 216 43 195 95 522 006 31 456 98 046 210 31 266 With any disability 23 863 097 85 217 11 750 311 54 860 12 112 786 52 673 With a sensory 5 422 873 43 111 3 081 424 30 448 2 341 449 25 740 disability With a physical 14 130 458 64 614 6 518 468 40 648 7 611 990 40 381 disability With a mental 9 234 123 52 168 4 659 370 28 646 4 574 753 36 550 disability With a self care 4 187 492 32 408 1 924 005 20 734 2 263 487 23 620 disability puna Ue 20215301 2 781 937 26 077 3 433 454 27 290 home disability With an employment 13 667 248 62 469 6 605 969 39 163 7 061 279 40 255 disability No disability 169 705 119 103 137 83 771 695 62 741 85 933 424 61 943 83 Table MEDIAN EARNINGS BY DISABILITY STATUS BY SEX FOR THE CIVILIAN NONINSTITUTIONALIZED POPULATION 16 YEARS AND OVER WITH EARNINGS 4 Estimate Margin of Error 37 With a disability 84 Appendix B Customer Observation Notes Observation Notes from Initial Meeting with SW Reso
27. Each sheet of rubber will have two holes punched in it so that when the first hole wears out it can be flipped and the second hole can be used Once the second hole wears out it must be replaced with a new part Several extra parts will be provided initially Should more be needed 12 x12 x 125 sheets can be ordered from McMaster Carr at http www mcmaster 300 com rubber and foam Ol rubber 1hOdpc The part will need to be cut using a sharp pair of shears and a 25 hole punch The dimensions are given in the figure below Properties of Natural Latex Rubber 2 x12 x 125 35A Soft Durometer rating 3760 PSI Tensile Strength 810 Stretch Limit FDA Compliant 110 ings ineering Drawi Appendix F Part and Assembly Eng co 15 32 77 77755 4 111 NOTES MATERIAL HOPE BREAK ALL SHARP EDBES SOL 425 me FLH Cu EDGE STE EC WFETEBIS ACE 5 aaa 5 ay 111 NOTES MATERIAL HOPE BREAK ALL SHARP EDGES ALL TOLERANCES 0 005 IN 4 ammo TRE 112 NOTES MATERIAL HOPE BREAK ALL SHARP EDGES ALL TOLERANCES 0 005 IN SOLID EDGE Tre POH STE EC SOG US Eno 113 114 115 E a H Fl iter
28. Figure 4 2 2 This design had no moving parts and the user would only have to roll the O rings off of the staff onto the part 17 PRESS D6uM HANDLE HOLDING FIXTURE FRONT VIEW SIDE VIEW Figure 4 4 1 Figure 4 4 2 The concept which initially received the most support from the team due to its simplicity 18 shown in Figure 4 4 3 This design concept is shown as it was originally drafted We repeatedly modified this design by considering replacing the spring with an air bag contraption or even just using a mechanical hard stop Figure 4 4 3 The process we used for our concept generation can be summarized as a move from fairly complex designs to simpler designs We incorporated different ideas from each of the initial concepts in order to develop the concepts the team decided were the most feasible to proceed with during the design process 5 0 Concept Screening and Evaluation Once we generated several different concepts we took all of the concepts which our team thought represented the best results of our brainstorming sessions and we analyzed these different designs in an attempt to determine which design was most feasible and would meet the customer requirements and target specifications in a way that was superior to the other concepts 5 1 Data and Calculations for Feasibility and Effectiveness Analysis As potential designs continued to be developed and modified during team meetings and on individual s own
29. Point Max Von Mises Max Deflection Convergence with Size in Stress psi in Respect to Previous Mesh 404 219 0205 E 3168 0213 33 1 3590 0215 47 Stress 3590 psi Figure 7 3 3 3 Von Mises Stress Concentrations The biggest concern here is that the stresses didn t converge quite as much as desired but the mesh wouldn t run for smaller element sizes This is cause for concern because the MATWEB yield stress for the part HDPE 18 listed as 580 4600 psi and McMaster Carr gave us a value of around 3500 psi What this means 18 that this part will deform plastically at the wall if it hits the ground at the correct orientation Since the Ultimate tensile strength 15 5000 6000 psi the part will not break The fact that the part will yield is not an issue for two reasons The first 1s that 4 this is a worst case scenario if the part is dropped and lands certain way The second is that if the wall were to yield or break it has no significant impact on the worker installing the o ring It simply just becomes a minor eye sore The second failure mode we investigated for the small O ring fixture using FEA was material failure due to fatigue in the rubber insert layer As the user presses the small pop nozzle part into the hole of the rubber sheet the o ring which initially rests on the rubber sheet will expand and roll onto the part During this installation process the rubber layer will deform and deflect downwar
30. QCD ENCORE PROJECT Mechanical Masters Team Members Jeremy Allen Joseph Diller Scott Leach Brent Morris Brian Reed Jonathan Robe June 10 2009 Abstract Mechanical Masters is developing assistive technology which will reduce barriers to employment advance for individuals with disabilities by increasing their productivity in the work place The specific task to be addressed 15 the installation of three different sized O rings onto the component parts of a syrup dispenser for a fountain drink machine By producing a device that will reduce O ring installation to fewer than 4 steps per O ring worker productivity is to be increased by 30 40 so that the customer can meet the target of 30 000 part assemblies per day In order to select the most effective design Mechanical Masters will be developing and prototyping two concepts simultaneously before making the final design decision Mechanical Masters developed three distinct prototypes each designed to assist in the installation of three separate O rings onto three different parts with unique geometries These prototypes were tested to determine that they met the project target specifications Although repeated testing indicated that the prototypes met the required performance specifications the customer s feedback indicated that the devices were not adequate for the workers needs The customer indicated that the devices needed to be made more user friendly for the workers and additional
31. Time Data 8 o rings by hand seconds 21 Table 7 5 2 2 Medium O ring Time Data 8 o rings by hand seconds 9 o rings using prototype seconds 30 36 Table 7 5 2 3 Small O ring Time Data 9 o rings by hand seconds 8 o rings using prototype seconds 35 54 From the time results the prototypes did not improve our times compared to hand installation We determined since we do not have dexterity limitations these results should have reverse affect for our customer thus our prototypes are designed to help once with limited dexterity Time was recorded based on the total amount of time it took for one of our team members to install 8 o rings for each small medium and large parts Table 7 5 2 3 shows the total time for the small o rings to be 35 seconds by hand and 54 seconds using fixture For the medium o rings the total time was 30 seconds by hand and 36 seconds with fixture Table 7 5 2 2 and 27 seconds by hand for the large o rings Table 7 5 2 1 From performing this experiment a lot of time was used during picking up the o ring from the table and setting it into it proper location for installation Our desired time to install the large O ring onto the QCD shaft would be eight seconds Timing some of the SW employees during fall quarter we found that it takes them an average of 15 5 seconds to install the o ring by hand Handling of the o rings seemed to be the main cause for slow installation times We feel that
32. ay catastrophically fail rendering the fixture completely unusable If our design were susceptible to this failure the cost and risk involved in operation could render this device unusable to our customer The second failure mode investigated for this fixture was material fatigue failure in the rubber insert Because the rubber insert layer plays a critical role the design facilitating the installation of the O ring with a relatively small input force if this layer were to fail the fixture would be temporarily unusable However as we discussed in Section 7 1 we designed the fixture so that this rubber insert layer could be easily replaced were the rubber layer to wear out However our design to be feasible must be robust enough to minimize the number of times the rubber layer must be replaced Therefore we wanted to ensure that the rubber layer would last about one year or one full production cycle for our customer For the drop test the part to be tested 1s the base for the small o ring fixture simluating a fall from table height approximately 4 feet high to the floor In order to test this the part has been cut down to a 1 5 x 1 5 x I cube for faster meshing Although convergence was not reached to the level desired the part could no longer be meshed due to such a small mesh size Given in Table 7 3 3 1 are the results of the three different meshes 45 Table 7 3 3 1 Mesh Results Mesh Size Refinement Nodes DOFs Elements As
33. ch unassembled laying on a flat surface 2 Grab a single part and a single o ring by hand and install the o ring onto its part Once the o ring is installed placed the assembled part aside or into a separate bin 3 Use a stop watch to record the time it takes to install all o rings onto all parts from the time first contact 1s made with an o ring until the final assembled part is placed in the bin 4 Using the fixture place same amount as in part 1 of o rings onto the space provide for the o rings and set the parts to the side on the table 5 Slide an o ring from the group into the appropriate slot of the fixture 6 Take a part from the table and insert it onto into the fixture installing the o ring Then place the part into a separate bin 7 Record the time it takes to install all o rings onto their respective parts Start the time at the first contact of an o ring and end the time when the final assembled part is placed in the bin The experimental results for time trials are shown in Tables 7 5 2 1 7 5 2 2 and 7 5 2 3 for the large medium and small O ring fixtures respectively For these tests we measured the 61 prototypes ourselves and not the employees of our customer Thus this data should not be definitive in assessing the actual productivity of employees with disabilities These data do however give a rough estimate of productivity rates for our fixtures compared to hand installation Table 7 5 2 1 Large O ring
34. d to the bottom corner of the base from a free fall of 4 ft was 29 91 Ibf This load was applied to one of the bottom corner nodes of the base Figure 7 The vector select option was used by selecting the direction to the opposite top corner of the base We assumed that the highest stress would occur if the base landed so that a straight line could be drawn from the corner that hits the ground 42 to the opposite top corner of the base The base was constrained in the positive 7 and negative y directions The opposite top corner of the base was pinned so that the blocks impact angle would remain constant Symmetry could have been used on this part since we are only interested in one particular area a corner The element mesh size was started off at 1 inch This was decreased by of an inch for each run until a mesh size of 0 5 inches was reached With a mesh size of 0 5 inches the maximum von Mises stress was approximately 665 psi and the maximum displacement was 0 0035 inches Figures 8 amp 9 The total number of nodes was 1034 and 3 102 degrees of freedom DOF From here a test for convergence was done by applying a local refinement with effective radius of 1 inch to the node of maximum stress The mesh size of the effective radius was decreased 14 inch increments until the maximum von Mises and displacement had leveled out This occurs at a final mesh size of 1 16 of an inch A maximum von Mises stress was about 635 psi and
35. date Jan 11 2000 Inventor Merle A Whetstone This patent introduces a design made to insert flexible O rings into a recess This device 18 particularly used for installing O rings into a half dovetail recess It is a simple design which makes the device lightweight and portable The ram mounted to a base consists of a chamfered edge to flex the O ring allowing it to pass over the lip of the recess A spring loaded sleeve is placed over the ram which also contains a chamfered edge For normal operation an O ring is first placed within the O ring cavity of the ram The part 18 positioned with the recess inward adjacent to the chamfered surface of the sleeve Next the part is pressed downward to engage the ram stretching the O ring Once the part contacts the top of the ram the chamfer forces the O ring into the groove using a constant distributed force The figure below is a schematic of the proposed tool 4 Figure 4 3 2 Face Seal O Ring Insertion Tool This tool utilizes physical properties that we are looking for in our design It 1s portable easy to use and relatively low maintenance We have also thought of ways to utilize chamfers to stretch the O rings Conceptually this design 18 like ours minus the movable ram Rather than a movable ram to directly install the ram the O ring is stationary while the part 18 used to apply the force to insert the O ring into its seat 15 Patent 3 O Ring Insertion To
36. disabilities and only 37 2 of these persons were employed For comparison in that same year over 60 of the general US population 16 years of age or older were employed The data also suggest that disabilities are a more pronounced problem for females because only 34 2 of females aged 16 64 had employment compared to 40 2 of males in the same age group 4 These data certainly suggest that unemployment is a more serious problem for persons with disabilities than for the general US population In fact the income levels for persons with disabilities is significantly lower than the income levels for the general US population indeed the median income for a person with a disability in 2006 was only 60 of the median income level for the general population 4 The U S Census bureau also reports data on disabilities on the state level According to the data the state with highest proportion of persons with disabilities is the state of West Virginia As of 2006 nearly 22 of the population ages 21 64 had at least one disability well over the national average 4 Details on these data are included in Appendix A This information is particularly relevant for the design project Mechanical Masters is working on since the customer we are working with is located in the state of West Virginia as described more fully in Section 1 4 1 1 Project Definition ME 470 471 472 is a senior capstone design project for the mechanical engineering undergraduate
37. ds Because of its elastic nature the rubber sheet will return to its initial state As the rubber sheet is subject to this alternating loading it could potentially fail due to fatigue We have estimated that over the period of one year this device will be used for 1 5 million cycles Since our customer needs this device for one year we will design our fixture to have a life of 1 5 million cycles According to one S N curve we have obtained for rubber for a lifetime of 2 million cycles the maximum stress 1s 2 2 MPa which is 319 1 psi Thus if the maximum stress in the rubber layer does not exceed this maximum stress value we can conclude that we have achieved our desired design specification According to experimental testing see Section 7 5 for further details we have determined that the input force required to press the small tip part into the rubber layer is 5 Ibf With this input force the o ring 1s installed In our FEA however we used a 10 Ibf since the user may actually 48 exert a larger force than is required for installation Initially we applied the principle of symmetry to analyze the entire fixture to see how the fixture would respond to this input force on the pop nozzle part Because the fixture rests freely upon a table the base of the fixture was constrained in the z direction A pin support was placed on one of the corners of the bottom face The plane of symmetry was constrained in the y direction A picture of t
38. e Nitrile aka Buna N rubber stretch limit of 300 with Natural Latex Rubber stretch limit of 810 7 5 2 Time Trials In performing this experiment a relative approximation of efficiency of the fixture can be determined The clients that will be using this design have mental and physical disabilities thus it would be difficult to simulate their compatibles to install an o ring Measuring the time of a normal person to install o rings and comparing with and without using the fixture will help to determine how well the device performs This experiment will show that using the fixture is more time effective than installing the o rings by hand The experiment involves recording the times of two processes the process of installing o rings by hand and the process of installing the same o rings using the designed fixture This experiment is significant because it determines the effectiveness of the design A relative efficiency scale can be determined by comparing the installation times by hand to those using the fixture The main purpose of the design is to improve the customer s assembly performance Reducing the installation time for such a repetitive motion will improve their productivity If the installation time is more using the fixture than by hand then using the design is nearly pointless The following procedure was conducted independently for the three prototypes 1 Have multiple parts with their respective o rings at least 10 of ea
39. e bottom face of the part was fixed in translation in the Z direction In the event of the part being torqued the pinned edges would be the only places where contact was made Figure 7 3 1 2 Loads and Constraints 27 The results of this analysis are summarized in Table 7 3 1 1 Table 7 3 1 1 Platform Stress Analysis Mesh Size in Max Displacement in Max Stress psi 1010 0 028 1185 5961 0 030 1317 41923 1400 Convergence was met as the stress did not increase much compared to the number of nodes The displacement is above normal because the HDPE material 1s somewhat flexible itself However the deflection of the material will be limited due to the orientation in the base The percent difference of the stresses 15 5 9 which is acceptable The yield strength is 3773 psi Thus the part will not fail with a maximum stress of 1400 psi Figure 7 3 1 3 Maximum Stress The second failure mode we analyzed for the large O ring design was bending in the O ring feed tray Initially all three designs incorporated this feature which would allow users to place O rings on the tray and then slide the O rings onto the fixture for installation However in the final design only the large O ring fixture incorporated this feature of the tray as distinct from the actual fixture used for installation Were the tray to fracture or bend the fixture s usefulness would be greatly reduced because the users would then need to place each O ring
40. e z direction The left and right sides were constrained in the y direction and the front and back faces were constrained in the x direction as shown in the following figure Refinement points were placed along the top outer edge of the hole in the rubber 50 Constrained in Tx Constrained in Ty Figure 7 3 3 6 FEA Model of Rubber Sheet With Loading and Constraints The following table summarizes the FEA results for this rubber sheet Table 7 3 3 3 Mesh Results for Rubber Sheet FEA Refinement Nodes Aspect Ratio Max von Max von Point Size Mises Stress Mises Strain in psi 0 03125 1506 10 12 165 1 0 03125 1525 173 8 0 03125 1842 161 3 For the refinement points the effective radius was 0 0625 in For the final mesh refinement points were added on the inner surface of the hole As we can see from the results presented in the table the model converged after two meshes Convergence was determined to be achieved because the results differed by only 7 19 The maximum von Mises stress was located as shown in Figure 7 3 3 7 51 Stress von Mises 52 161 2957 145 3558 128 4158 113 4758 97 53596 81 59601 65 65606 49 71612 33 77617 17 83623 1 896285 Time 15 Time Step 20 of 20 Maximum Value 161 296 Ibf in 2 0 000 0 510 in 1 020 1 530 Minimum Value 1 89628 Ibf in 2 Figure 7 3 3 7 Location of Maximum Stress The location of the maximum von Mises strain is shown in Figure 7 3 3
41. egs are the location of failure then it is possible that the fixture will not operate according to design 2 Include some discussion justification for the rating for probability of occurrence OCC If we make the tray out of sheet metal then only relatively large loads would cause major deflection or bending in the fixture This would most likely happen during transportation or maintenance of the fixture than during the normal operation or setup 3 Include some discussion justification for the rating for probability of detection DET It will be relatively easy to detect deflection or bending in the metal feed tray 4 Recommended actions to achieve acceptable risk Make specific recommendations for action and include some discussion of the alternatives that were considered the person s responsible for completing the actions and the completion date Design the fixture to have a substantially larger top surface area so that we can eliminate the metal feed tray 5 Notes on Completed Actions Our updated design has eliminated the need for the metal feed tray for the small o ring fixture The device will be roughly 1 x 1 with short vertical walls on the top surface to contain the o ring during operation 93 Potential Failure 7 Stripping of internal threads in plastic base internally threaded member Evaluation Results ___8 l Potential Cause s Mechanism s of Failure 3 Probability of occurr
42. ence OCC Current Controls for Detection and Prevention Probability that failure is detected and prevented DET Risk Priority Number RPN SEV OCC DET b do 0 1 Include some discussion justification for the rating for severity SEV If stripping of the internal threads in the plastic base does indeed occur then the top plastic and rubber layers as well as the feed tray will no longer be firmly attached to the base The entire fixture will likely become unusable because the layers will not be held in place as is required by the design Potential Effect of Failure Severity SEV 2 Include some discussion justification for the rating for probability of occurrence OCC It is more likely that thread stripping will occur in the plastic base than in the screw threads Depending upon the quality of plastic thread stripping may be very likely in the plastic base 3 Include some discussion justification for the rating for probability of detection DET It will be fairly easy to detect this failure mode As the threads are stripped over time the problem will be noticed whenever the fixture 1s disassembled for maintenance 4 Recommended actions to achieve acceptable risk Make specific recommendations for action and include some discussion of the alternatives that were considered the person s responsible for completing the actions and the completion date Eliminate any need for bolts and bolt holes in the p
43. ent tables The parts with the O rings applied were to be deposited into part bins which were to be taken to a separate station for final product assembly The device must be sanitary and be disinfected once a day The project manager or supervisors are going to supply the parts including the O rings to the workers Each ring assembly will likely be color coded The fixture is to fit in the kitchen sink 15 in x 15 in About 80 workers total will be working on the project They will assemble 4 million parts the first year with roughly 200 000 parts per year after that first year The part bins will be color coded then weighed to get the number of parts each worker has assembled Workers are paid based on their part output Observations of employees current performance Employee 1 Severe mental disability with some physical disability Averaged 1 size M o ring every 15 seconds Employee 2 Moderate mental disability no physical disability Averaged size L o ring every 6 seconds 86 Appendix C FMEA Worksheets Failure Modes and Effects Analysis for Safe Reliable Effective Designs Step1 Provide a description of the full system including all subsystems and accessories in all modes of operation including storage setup transportation operation cleaning maintenance etc If possible please include sketches with users in operating positions for the main operating modes This information can be included here or as an attachme
44. er material in the design so only the small O ring fixture includes this material As is discussed in Section 7 5 1 this rubber was replaced with Natural Latex Rubber stretch limit of 810 after we tested our first generation prototypes For all of the materials we used brass inserts with screws as the fasteners and connectors For the reasons discusses in Section 7 1 we decided not to drill any threaded holes in the plastic bases because of concerns over thread stripping For O ring trays in the medium and large O ring fixtures we used Lexan instead of metal because Lexan provided us with excellent strength characteristics and yet was very low weight We also used stainless steel rods in both of these designs 7 3 Design Analysis For our preliminary design analysis we employed finite element analysis as a method to explore different design issues and potential failures in a non destructive way prior to actually manufacturing our prototypes Using the results of this method we could analyze our system s stability and robustness without incurring extensive costs associated with repeatedly testing real prototypes which were subjected to destructive testing We tested each of the three designs independently using FEA Some of the test simulations we performed were similar for each of the three designs but they all had to be performed because each design differed from the others We also performed FEA on O ring fracture which is applicable to
45. er our project selection we determined the customer s needs given the observations we had made during our visits of SW Resources facilities The following tables show a list of customer needs that our group will strive to meet and the order of importance of these needs Table 2 2 1 gives a general listing of customer needs Table 2 2 1 Initial Customer Needs List Obtained From Interviews and Observations Versatile covers a variety of disabilities sanitary simple No maintenance required Safe Affordable Cuts assembly time Lightweight compact After we identified the general customer needs we created a hierarchal list of the customer needs as a team so that we could rank the needs in order of importance This hierarchal list of customer needs would provide us with the basis for our future weighting of customer needs Table 2 2 2 gives this hierarchal list Table 2 2 2 Hierarchal Customer Needs List 1 Safety 1 1 Low Risk for hand operation 1 2 Low noise 1 3 No sharp edges 1 4 Enclosed mechanical components 2 Sanitary 2 1 Parts will not rust or deteriorate 2 2 Easy to clean on a daily basis 2 3 Lubrication must be enclosed if used 2 4 Water proof 3 User Friendly 3 1 No more than 2 3 steps involved 3 2 Easy for anyone to understand 4 Cost 4 1 Minimal cost 5 Size 5 1 Able to fit in a utility sink 5 2 Easy for a single individual to carry 5 3 Fits on a standard table 6 Low Maintenance 6 1 Easy to maintain 6 2 Low mai
46. es with varying levels of disability need a device to assist with handling and installing O rings onto their respective components for the syrup dispenser for fountain drink machines Target Specification can be found in Table 3 2 1 These target specifications were drawn up by the team and later sent to the customer for approval We knew that the device would be most effective for the customer if the per unit cost were less than a couple hundred dollars so we determined that the target specification for the cost would be 200 Since the device would need to be sanitized regularly we decided to limit the materials used for the device to ones which were rust and water proof If our device were to improve productivity we would have to use 3 steps or fewer for the O ring installation The size of the device also was of concern to our team We wanted the device to have a low enough weight that a single person could easily and comfortably carry it and we wanted the device to be able to fit inside the sinks available at the customer s facilities Initially we targeted a maximum volume of ft but realized that the correct volume should be 1 5 ft the volume of the sinks the customer has The target specification for the aspect ratio 1s the ratio between the width of the device to the height or depth Thus according to this specification the width should not be more than three times the height or depth of the device Table 3 2 1 Installation time
47. fic attention during the design process and prototype construction and testing were incomplete O ring installation stripping of threads bending in O ring feed tray and fatigue failure in rubber components Because we had determined that the best course was to develop three separate devices each one focusing on the installation of a different O ring our response to the FMEA results differed depending on the device For all of our devices we decided to eliminate the metal O ring feed tray thus the probability of occurrence for bending in the feed tray drops to 0 To eliminate any problems associated with stripping of threads we determined to eliminate any threaded holes in any plastic materials Instead we decided to use threaded metal inserts for any fasteners which would attach plastic parts together in the devices After these actions were taken we revised our FMEA and the new results are given in Table 7 1 3 Table 7 3 1 Revised FMEA Results Compared to Initial FMEA Assessment 1 O ring notinstalled 378 0 2 FracureofOxing 84 42 3 Fatgueinrbbr 96 27 4 Corrosion due to cleaning 28 20 5 ShapEdgs 007 9 6 Bendingino ringfeedtray 98 0 7 Stripping ofthreads 14 0 8 Fracture if dropped 70 35 We determined that the revised RPN numbers were satisfactory However throughout the manufacturing process of the initial prototype we focused on adjusting our designs to i
48. ficient data points are collected The experimental setup for the test applied to the medium O ring fixture is shown in Figure 7 5 1 1 We used this same setup for the large O ring fixture as well Figure 7 5 1 1 Experimental Setup for Input Force Testing Figures 7 5 1 2 and 7 5 1 3 show the experimental setup for the input force testing for the small O ring fixture Using this procedure we calibrated the force sensor by placing the unloaded fixture onto the scale and set the measured force to zero We then installed the O ring onto the part by pressing the part into the fixture The scale then measured the input force required to install the O ring successfully 55 Figure 7 5 1 3 Installing O ring 56 The force time profile for the input force for the large O ring Fixture is shown in Figure 7 5 1 4 which shows results for multiple trials According to this data the force builds up to the point where the o ring is installed and then rapidly decreases to zero Table 7 5 1 1 shows the summary for the maximum force during the installation motion Input Force vs Time 2 i Time sec Figure 7 5 1 4 Force Time Profile for Large Fixture 27 Table 7 5 1 1 Input Force Testing 4 wraps of rubber band Input Force Ibs 7 19 7 74 6 65 9 3 7 6 23 L3 9 10 8 65 From these results we see that the maximum input force required to install the o rings 18
49. h using rubber to act as a cushion similar to the final design of the small o ring device A layer of rubber was used with a small hole cut out to allow for the part during installation This method work well as far as installing the o ring but once the o ring was installed pulling the part with the o ring back through the rubber was a problem A high force was required to pull the part back through somewhere along the order of twice as much effort to pull the finished part back through the rubber as pushing it This it was apparent this issue needed resolved Through addition experimentation with different group member s ideas the one that seemed to work the best was the use of steel rods The o ring is placed on top of two equal rods that are pulled together by elastic bands and separated by a wood boss in the center Force tests were performed using this method and were satisfactory The use of two rods to install the o ring onto the medium part was carried through to the final design For the final design the base was manufactured from HDPE The basic shape of the base was initially cut to shape using a vertical band saw A CNC mill squared the sides of the base and machined the necessary pockets to equip the base with the installation rods Stainless steel rods were chosen for the final design The rods offer corrosion resistance and excellent wear resistance When experimenting with the prototype it was determined that an o ring set guide
50. had difficulty in handling the small parts and O rings which prevented them from correctly orienting the parts for installation Thus because of handling issues we have determined that this design does not adequately address customer needs We conclude that these designs are not ready for production due to the incompleteness of the design The customer feedback was essential in determining the capabilities and limitations that the user s encounter Future work would involve the development of an ejection system and possibly reduce the overall manufacturing by combining parts We determined that our target specifications do not adequately address the customer needs therefore any future work done on 77 V this project should revisit and restate the customer needs The reason we did not correctly address customer needs and expectations was that the customer had not begun their project until we had already begun prototype manufacturing and testing Thus our statement of needs and specifications was based on expected not actual customer needs and technical specifications 78 References p l 10 11 12 13 The American Heritage Dictionary of the English Language Disability Fourth Edition 2000 available at http www bartleby com 61 80 D0248000 html accessed on October 18 2008 SW Resources SW Resources Welcome available at http www swresources com accessed on November 11 2008 SW Reso
51. his model 18 shown in the figure on the top of the next page Since we used only half of the model the applied force was half of the expected force 1 the applied force was 5 Ibf 0 000 2 782 in 5 565 8 347 Figure 7 3 3 4 Model of Fixture Using Symmetry When this mesh was run the results indicated that stress concentrations existed only in the rubber layer and not in the top plastic cover or in the plastic base This model was further refined by using only a small block surrounding the hole in the rubber sheet The bottom face was constrained in the z direction and the cut planes were constrained in the x and y directions Again the FEA results indicated that stress concentrations existed only in the rubber layer and did not extend to any other parts as shown in the figure on the next page 49 Time 15 0 000 0 873 in 1 746 2 619 Time Step 20 of 20 Figure 7 3 3 5 Stress Results for Block Assembly of Small O ring Fixture Because there were technical problems with successfully getting this model to mesh correctly and because stresses were located only in the rubber layer the final FEA looked at only the rubber sheet For this analysis we used a 10 Ibf surface load in the negative z direction For the applied load we used the maximum value for the alternating load the load alternates between 0 and 10 lbs Because the rubber layer rests upon the base of the fixture the rubber sheet was constrained in th
52. ial operation tolerance factor Labor overhead equipment cost g c 1 4 0 528 58 519 515 515 h Purchased Materials Component Cost E La wa wa s 1 TOTAL The total cost to produce one of these fixtures is estimated to be 190 Since the size of the raw materials were sometimes significantly larger than the size desired 1 e the rubber sheet and screws the cost was divided based on the amount of material used rather than using the total cost This does not have a major effect on the final cost because the rubber sheet was 25 80 and the screws were 5 37 On all other materials the correct size was able to be purchased from the supplier Overall the small o ring fixture was relatively easy to manufacture and assemble however the fabrication of the base and the top cover was more complex To do this follow the steps as given below in conjunction with the assembly part drawings given in Appendix F 1 Rough cut the opposite corners from midpoint to midpoint of the 12 x12 x1 HDPE using a vertical band saw Face the new surfaces using a vertical mill to obtain the desirable surface finish 2 Mill out both pockets of the base T5 S 001 in which the rubber T5 S 003 and top cover T5 S 004 will later be attached 3 Using scrap from step 1 mill out a piece of HDPE to the length and width Note the thickness will be milled down later to be used for part T5 S
53. ill begin This 1s a crucial step in developing the final design from concepts one and two Because we do not have enough information yet to determine which of these concepts will yield a better design mockups of both designs will be manufactured in order to test and compare the differences From this a final design will be agreed upon using the best features of each concept 26 6 1 Final Concept Diversification Prior to any mock up construction we identified a potential weakness in all of our design concepts because none of them incorporated a method for feeding the O rings into the fixture to be installed To correct for this we added a metal O ring feed tray to our fixtures This tray 18 shown in Figures 6 1 1 and 6 1 2 Figure 6 1 1 Concept 1 for O ring Feed Tray 21 Figure 6 1 2 Concept 2 for Feed Tray At this point the team had focused on generating a single design which could be used to install all three of the O rings However after initial mock up construction and testing the team determined that the unique geometries of the three parts and the different problems encountered with the installation of the three different O rings three separate designs should be explored for the three O rings The first concepts for the three distinct designs are shown in Figures 6 1 3 6 1 4 and 6 1 5 28 Figure 6 1 3 Design Concept for Small O ring Fixture Figure 6 1 4 Design Concept for Medium O ring Fixture 29
54. individually on the fixture for installation instead of placing a large quantity of O rings onto a tray and then moving each one into place 38 The tray was analyzed with a 24 pound force on the outer edge This force was calculated using the impulse momentum equations Constrained on the face where it meets the part fixed Plate elements were used with mid plane meshes This analysis 18 the worst case loading scenario for the tray The loads and constraints applied to the tray are shown in Figure 7 3 1 4 Figure 7 3 1 4 Loads and Constraints Table 7 3 1 2 summarizes the results of our analysis Table 7 3 1 2 Force on Tray Results Mesh Size Stress VM psi Strain VM 5 15224 1 243 25 123336 0046 2 23567 1222 2370 8 0052 3072 1 123787 0057 4566 39 Stress won Mises 2370 17 2151 645 1933 121 1714 598 1496 072 1277547 1059 023 840 4885 627 974 403 4496 184 9251 4 429 8 844 Figure 7 3 1 5 Maximum Stress Convergence was achieved to a final value of 2378 15 psi This was checked by comparing the number of nodes to the increase in stress Lexan has a yield strength of 8300psi matweb From this I conclude that the tray should be able to survive a 4 foot fall with an impact on the rear edge Since this prototype contained more parts as well as a large Lexan tray drop analysis was necessary in developing a durable device The yield strength of Lexan was found to be
55. ing the o ring on top of the rubber The user then picks up a part and presses down on the o ring and the rubber will force the o ring over the chamfer of the part It is important for the user to correctly orient the part for installation The part must be inverted so that the tip of the part is pressed down into the hole and into the O ring The plastic base acts as a hard stop for pressing the part into the hole When the rubber layer is compressed to the maximum allowed by a 15 Ib input force the approximate maximum force that a user will apply the part can no longer be pressed down unless significantly more force will be applied More detailed instructions and precautions can be found in the User s Manual in Appendix E 68 9 2 Cost Estimation and Manufacturing and Assembly Processes 9 2 1 Large O ring Fixture Many of the components of the design are made from HDPE and required intricate milling for precise geometry In order to satisfy this design CNC milling is required for many of the parts including the base the angled top the platform and the part holder The tray and bottom stabilizer can be made from use of a band saw and sheet metal bender The surface finish is acceptable from the finishing left from the milling Drawings of these parts can be found in the Appendix F Many of the components of the design are made from HDPE and required intricate milling for precise geometry In order to satisfy this design CNC milli
56. ion allows the teams to tackle real world design problems and to work with real clients Second by centering the project around helping individuals with disabilities the class 18 able to give back to the local community and provide a community service This Capstone Project also has several goals aimed at developing the students professional skills by specifically addressing their ability to work well with other people in the same team and by improving their technical skills by providing an opportunity to use their technical skills and knowledge in the design process The purpose of the Capstone Project is four fold according to a description of the Program Educational Objectives Statement 11 I Prepare Graduates for engineering careers and advanced education Graduate mechanical engineers with technical skills Graduate mechanical engineers with skills to perform in the work environment Graduate mechanical engineers who are informed and aware of contemporary issues and the impact of engineering on society ad 1 3 Initial Needs Statement There is a need for assistive technology devices that reduce barriers that prevent persons with severe disabilities from entering or advancing in the workplace Devices are needed to address environmental accommodation functional assistance and mobility issues for people with cognitive disabilities developmental disabilities and physical impairments vision hearing and mobility 10
57. isk of harm to be very small after operating the fixture ourselves and observing the customer operating it as well All three fixtures are constructed with FDA compliant materials making them sanitary and 76 easily washable The simplistic operation of the fixtures is easy for workers to use In fact customer feedback indicates that the users enjoy using the fixture as it makes the workers more interested in their work The designs incorporate four basic steps for operation place o ring orientate and place part push part down to install O ring and remove part after installation is complete These steps are easy to understand the users could operate the devices correctly once they were shown how to do so and gained experience operating the devices The total cost is about 424 for one Large O ring fixture 287 for the Medium O ring fixture and 187 for the Small O ring fixture The Medium and Small O ring fixtures met our target specification of less than 300 The cost for the large O ring fixture exceeded our specifications The fixtures are small enough to fit into a sink and are small enough so that there 1s enough room on a table for several of them Once assembled the Large and Medium O ring fixtures have only one required maintenance feature which 18 the occasional replacement of the rubber bands The rubber bands will wear out after extensive use The only required maintenance for the Small O ring fixture 1s replacing the rubber la
58. ith the use and operation of the fixtures Because we developed three separate fixtures each design to assist with the installation of different sized O rings on different sized and shaped parts we had to independently test each of the three prototypes We designed two specific experiments to measure the performance of the prototypes we constructed The first test was a force measurement test designed to measure the ease of use associated with the operation of our fixtures Ease of use 18 here defined to be measured by the minimum input force required to successfully install an O ring The second test we performed was designed to measure the productivity rates using our fixtures compared to the productivity rate of installing O rings by hand Here productivity is defined as the number of O rings successfully installed in a specified period of time 7 5 1 Input Force Measurements In performing this experiment an approximate required input for will be known Using an accurate force gauge will enable the experiment to produce accurate results The experiment is designed to easily determine a required input force for each of the o ring installations A target input force would be about 15 pounds This target input force was calculated based upon the maximum force a single finger can exert According to one study we found the maximum force exerted by a single finger is approximately 100 N 22 7 1580 16 Since we are designing these fixtures for comfor
59. lastic base 5 Notes on Completed Actions Our updated design for the small o ring fixture has eliminated any need for bolt holes Thus we will not have any threaded holes in the plastic base or even in the top plastic layer 04 Potential Failure 8 Fracture of fixture if dropped Operating mode when failure could occur Potential Failure Mode ne MH operation Initial After Action Evaluation Results Potential Effect of Failure Severity SEV 100 5 Potential Cause s Mechanism s of Failure 7 7 Probability of occurrence OCC Current Controls for Detection and Prevention Probability that failure is detected and prevented DET Risk Priority Number RPN SEV OCC DET 1 Include some discussion justification for the rating for severity SEV If the fixture were to fracture upon dropping it would render the device inoperable however the user would not likely be harmed Therefore we dropped the severity from 10 to 5 2 Include some discussion justification for the rating for probability of occurrence OCC Potentially there are many causes which could lead to the devices being dropped during operation The user may accidentally bump the devices on the table on which they rest causing them to fall to the floor Also since the devices need to be cleaned on a daily basis the workers responsible for cleaning the devices could drop them during the cleaning process This would be easy to do when the devices were
60. loyees 2 1 Customer Project Selection In order to do accurately determine our customer s needs our group met with SW Resources several times to get an overall view of what needs to be accomplished and to view the resources available at their facility The first time that we met with SW Resources we toured their facilities and overviewed several of the different divisions of the company including SW Industries Mail Plus and SW Designs During this trip we met with several employees in management positions and also met with several of the employees who have disabilities The managers showed us several of the projects which SW Resources was currently engaged in as well as several projects which they are about to begin The observation notes which we took during this meeting are included in Appendix B From this meeting we were able as a team to discuss our options and decide which project we would choose if SW Resources became our customer The project which we selected would determine the specific customer needs since SW Resources is involved in a diverse range of projects and its employees have a large range of disabilities After this first preliminary meeting with SW Resources we decided that we would like to work with them and we selected their Widget Project the assembly of a syrup dispenser for fountain drink machines used by restaurants We specifically decided to work on the O ring assembly 2 2 Customer Needs Identification Aft
61. lume target specification lt 3 ft and simple geometries of each design Each concept would meet the productive criteria since each design is projected to allow for an O ring to be installed in less than 4 seconds Each design also operates with a force being applied in a linear motion which installs the O ring in one step Placing the O ring on the guide 15 another step totaling 2 which meets the target specification of O ring installation 5 2 Concept Screening Throughout the quarter our team has made two personal visits to our customer SW Resources located in Parkersburg West Virginia Other than the personal visits regular contact has been made with Kellie Conrad manager through email and phone calls After the first visit our group met for an initial brainstorming session where each member presented their own initial ideas for installing the 3 O rings on the QCD Encore The main factors taken into consideration while brainstorming are listed in Table 5 2 1 22 Table 5 2 1 Concept Generation Criteria Manufacturability User Friendly 5 3 Concept Development Scoring and Selection The approach used for developing the best concept for feasibility was by comparing each concept to the criteria established by the team to fulfill the target specifications These requirements include safety manufacturability sanitary user friendly maintenance and cost On a range of 1 to 5 with 1 being the least important and 5 being
62. me discussion of the alternatives that were considered the person s responsible for completing the actions and the completion date The risk 1s fairly low for this mode of failure The only option to reduce the risk is to find a better grade of rubber or an alternative design not requiring rubber 5 Notes on Completed Actions We used only FDA compliant materials for our devices so all materials were designed to be able to withstand basic sanitary operations 91 Potential Failure 5 Safety risks due to sharp edges Operating mode when failure could occur Potential Failure Mode Initial After Action Evaluation Results Setup transportation storage operation cleaning Potential Effect of Failure Severity SEV Potential Cause s Mechanism s of Failure Probability of occurrence OCC Current Controls for Detection and Prevention 1 1 Probability that failure is detected and prevented DET Risk Priority Number RPN SEV OCC DET o 2 9 1 Include some discussion justification for the rating for severity SEV If there is a sharp edge or pinch point then it is a serious safety issue 2 Include some discussion justification for the rating for probability of occurrence OCC This should not occur as long as we double check and make sure all edges are rounded and no pinch points exist 3 Include some discussion justification for the rating for probability of detection DET Not necessary
63. me with the fixture Once again the individual tested did not have trouble handling the o ring while the employees at S W Resources will run into that problem The team did run a time trial and it took 27 seconds to install 8 O rings for the large O ring 8 0 Design Refinement for Production Z The final prototype for the large o ring installation was the most challenging to select because the geometry of the stem part does not allow for the o ring to simply slide into the groove To gather different concepts we simply studied the part and the o ring as a team While searching for different concepts to install the o ring we found that the most reliable method was to align the part nearly perpendicular to the o ring and roll the o ring over the part head and into the groove From this we came up with two different concepts and used FMEA to select different concepts d Figure 8 0 1 Concept one for large o ring Figure 8 0 1 Final design selection The first concept much like the final design utilized steel rods to slip the o ring onto the stem One key difference between the two was the moving parts The first concept held the part stationary and used a lever arm and bracket to move the rods over the stem while the final design holds the rods stationary and allows the part to move vertically through the rods Comparing different failure methods we decided that concept one had more failure modes due to the complexity of
64. most important the team determined the level of importance each one is to our design This number was multiplied by the average level of importance which was determined by allowing each team member to compare the concepts to each of the design criteria This consisted of determining the level of importance each concept has on the design criteria by rating them from 1 to 5 as before By taking the sum of the product of average level of importance and criteria concept 2 was weighted the largest Table 5 3 1 shows this method used Once the concepts were compared to the criteria the next step was to evaluate them on whether or not they meet the target specifications Table 5 3 2 The target specifications are based upon the work area and production levels observed during one of our visits to SW Resources If any of the concepts exceed the specified target specifications it will be hard for SW to use thus may be ruled out 23 Table 5 3 1 Design EFT Concept _ Table 5 3 2 Target Specifications YY vomis Y Y L mesi Y 900 parts per hour 30 40 production increase Criteria Standards Safety Will device be safe for workers Will any moving parts be dangerous to workers hands Manufacture Does the team have the ability to manufacture the concept Do we have the resources sanitary Would it be possible to use
65. mprove the actual installation of the o rings Since the revised RPN for unsuccessful O ring installation was the highest we determined that we should focus efforts on improving the design to allow for easy and consistent operation and installation After finite element analysis described in section 7 3 we determined that the fracture of the o ring fracture of the fixture and fatigue in the rubber were not likely to occur in our design More details on the tests and our conclusions are given in 34 Section 7 3 By rounding all corners and edges we eliminated any safety hazards sharp edges would cause and we selected materials for our prototype that were specified by the manufacturer to be corrosion resistant By eliminating any need for threaded holes in the plastic we determined that stripping of the threads was no longer a potential failure in our designs 7 2 Prototype Material Selection The most important requirement for our materials is that they would be FDA compliant For this reason we decided that for most of our materials we would use a plastic with good wear characteristics and one which would not be susceptible to corrosive wear due to repeated cleaning We selected high density polyethylene HDPE as the primary material for our fixtures The rubber material we initially incorporated into our designs was Nitrile aka Buna N rubber stretch limit of 300 However we determined that two of our prototypes would not use a rubb
66. n a scale of 1 to 10 To determine the potential severity of failure we had to consider whether the device would perform the desired task reliably and whether the user might be harmed through use In order to estimate the probability of occurrence we considered the risk of harm associated with use of the device and what factor of safety should be incorporated into the design Finally to determine the probability of detection we assessed the likelihood that any failure would be discovered by the user prior to the time when failure would occur Table 7 1 1 gives the details of the scaling we used in our numerical weightings 15 We could then obtain an overall estimate for each identified failure mode a Risk Priority Number RPN by calculating the product of the severity occurrence and detection Table 7 1 1 Description of Rating Scale for FMEA Rating Potential Severity Likelihood of Occurrence and Avoiding Device works no impact No chance of occurrence 100 chance of detection on device performance no significant operating and avoidance danger to user experience low uncertainty Device works but with poor performance no danger to user based on analysis only Device works some detrimental impact on performance some danger to user Device cannot be operated Very poor information 096 chance of detection very serious danger to user about loads or operating and avoidance conditions wild gues
67. ng transportation Text here Initial After Action Evaluation Results Potential Effect of Failure Severity SEV es Potential Cause s Mechanism s of Failure 89 Probability of occurrence OCC Current Controls for Detection and Prevention Probability that failure is detected and prevented DET Risk Priority Number RPN SEV OCC DET 1 Include some discussion justification for the rating for severity SEV If the rubber layer fails due to fatigue the device really is not very operable at least at desired performance levels but the user is not harmed in any way 2 Include some discussion justification for the rating for probability of occurrence OCC Final value for occurrence is based on FEA analysis for fatigue failure 3 Include some discussion justification for the rating for probability of detection DET It would be fairly easy to detect fatigue failure in the rubber As the material wears down its performance would gradually reduce The rubber layer will not catastrophically fail in a very dangerous manner 4 Recommended actions to achieve acceptable risk Make specific recommendations for action and include some discussion of the alternatives that were considered the person s responsible for completing the actions and the completion date Perform a finite element analysis on the rubber layer to determine if the rubber material is robust enough to last for the desired length of time Find
68. ng 18 required for many of the parts including the base the angled top the platform and the part holder The tray and bottom stabilizer can be made from use of a band saw and sheet metal bender The surface finish is cceptable from the finishing left from the milling All manufacturing operations are subject to the capabilities of the manufacturer The standard tolerance for all parts in the Large O ring Fixture is 0 005 The materials for each part are listed on the drawings Table 9 2 1 1 Cost Estimation for Large O ring Fixture Cost Details for Large O ring Fixture assembly line eee EC part spring a Total time to complete operation 1 5 0 2 1 pues EE hours b Labor rate for the m NEN 1 1 1 1 1 1 _ 025 05 te te n Cost TOTAL 0 00 The fixture costs can be seen in Table 9 2 1 1 69 9 2 2 Medium O Ring Fixture The medium o ring fixture is simple to assemble The manufacturing aspect 18 complex Following the steps below in conjunction with the assembly part drawings given in Appendix manufacturing is quite simple Overall the small o ring fixture was relatively easy to manufacture and assemble All operations performed on a CNC vertical mill unless otherwise stated in the following procedure 1 Rough cut the basic shape of the base 10 X 3 X 2 75 usi
69. ng a vertical band saw Square sides of base using a CNC or Vertical Mill 2 Mill out top pocket of the base leaving two 0 375 diameter bosses 3 Plunge drill a 0 375 diameter hole 1 965 center of pocket 4 Using a 0 625 counter bore drill center hole 1 305 deep 5 Four 0 190 mounting holes 0 375 deep are placed symmetrically around the top of the base to allow brass inserts to be place 6 Machine set guide from HDPE 0 625 diameter Counter bore 0 375 diameter 0 25 deep in the bottom of guide This allows spring to seat into guide 7 Using adhesive glue a 0 375 spring into the base of guide 8 Use adhesive to glue the brass inserts into the four tray mounting holes 9 Place set guide and spring into center hole 10 Cut two 0 375 diameter 304 stainless steel rods roughly 3 250 in length using horizontal band saw 11 Take cut rods to a lathe to cut grooves 0 250 from each end 12 Using a carbide grooving tool cut grooves roughly 0 250 deep and as wide as the tool 13 Remove burrs from rods and install 2 wraps of an elastic band at each end 14 Place rods with bands attached into milled pocket of bass and allow rods to close against the bosses 15 For the o ring tray cut out a square piece of 0 125 thick lexan based from the drawing dimensions 70 16 Using a sheet metal brake bend 3 sides both short and one long to a 90 degree angle 17 Using a 0 625 hole saw on a vertical drill press cut
70. nt to this document Modes of operation Storage setup transportation operation and cleaning Step 2 Identify all potential failures and safety hazards for the system in each mode of operation A failure is any undesirable occurrence associated with the system If multiple failure modes have a common root cause please compile them together and identify the root cause O ring is not completely installed Fracture of the o ring Fatigue in the rubber sheet Material wear corrosion due to cleaning Safety risks due to sharp edges in metal feed tray Bending in metal o ring feed tray Stripping of threads plastic base Fracture of fixture if it is dropped Step 3 For all significant potential failure modes in step 2 complete an FMEA table to determine the type of action necessary to achieve acceptable risk level and the priority of the action compared to the other failure modes 87 Potential Failure 1 O ring is not completely installed Operating mode when failure could occur Potential Failure Mode Operation Text here Initial After Action Evaluation Results Potential Effect of Failure Severity SEV _ ee Potential Cause s Mechanism s of Failure 3 Probability of occurrence OCC Current Controls for Detection and Prevention Probability that failure is detected and prevented DET Risk Priority Number RPN SEV OCC DET 88 90 1 Include some discussion justification for the rating for seve
71. ntal Accommodation Environmental Control Unit systems work site modifications ergonomics farming and other rural interventions universal design of products places and systems 5 Functional Control and Assistance rehabilitation robotics functional electrical stimulation prosthetics and orthotics 6 Service Delivery technology transfer telerehabilitation 7 Seating and Mobility seating and wheelchair interventions seat pressure measurement transportation 188168 1 2 Project Scope and Goals There are several goals which we as a team seek to achieve as the result of this project Some of these goals are the result of the type of project we are to select as outlined in Section 1 1 while others are the more general goals we have as a team for completing our capstone design project The general purpose of the NISH competition is to increase the employment opportunities of specific individuals with disabilities by increasing their work productivity By creating assistive technology designed to overcome the barriers caused by the disabilities the NISH competition seeks to advance these individuals in the workplace If the individuals are without employment but are seeking employment the NISH competition seeks to provide the individuals with the ability to find the employment that they seek There are several reasons why the Senior Design Capstone Project 18 focusing on the NISH competition this year First entering such a competit
72. ntenance cost 2 3 Weighting of Customer Needs We employed the Analytic Hierarchy Process AHP to determine the relative importance of each of the six customer needs identified in Table 2 2 2 shown previously According to the organization responsible for defining this process AHP is a structured method for helping people deal with complex decisions It provides a comprehensive and rational framework for structuring a problem for representing and quantifying its elements for relating those elements to overall goals and for evaluating alternative solutions 12 This method allows people to determine benefits costs and dependence during the decision making process We employed this method to determine quantitatively the order of importance of the six customer needs Table 2 3 1 shows the results of our analytical hierarchy process of weighting these six customer needs We determined the individual relative weightings in columns 1 6 by group consensus that is as a team we decided unanimously what the relative importance of safety was to sanitary etc We then computed the weights for each need As can be seen from the table sanitary was determined to be the most important identified need Table 2 3 1 Analytical Hierarchy Process Weighting of Customer Needs User qe User Friendly 22 ix 3 0 Revised Needs Statement and Target Specifications Normally we would observe the current processes SW Resources uses
73. ol 9 Patent number 5050282 Filing date Aug 27 1990 Issue date Sep 24 1991 Inventor Frank Zannini This patent introduces a way of installing flexible O rings The device was created to insert O rings into an inner groove of electrical connectors It consists only of a shaft and a cylindrical slider or contact member to install the seal The shaft end 1s flared to force the O ring into its seat while the tool 1s removed The contact member has a section that has been removed This is done so only one side of the O ring 18 in contact with the tool enabling the O ring to slide into the groove one side at a time Although this device 1s used for installing internal seals some of the techniques could be useful Sliding the O ring one side at a time is something we are researching We have also been discussing the feasibility of a cylindrical cone type shape to slide an O ring over the part lip into its seat This design uses the same concept giving us good evidence that this idea 1s feasible Figure 4 2 3 O ring insertion tool 16 42 22 29 40 8 ae Ie SN 77777777 Ek x SS 27 6 FIG 3 48 Figure 4 2 4 Tool inserted into electrical connector and installing a seal 46 22 E 4 4 Concept Generation In order to generate several separate and individual concepts our group began by having each team member come up with two design sketches on their
74. our installation time will be around 5 seconds part For the SW employees 10 15 seconds is more likely at the beginning of testing We are hoping that they will catch on and reduce their times to 8 seconds However once we have delivered the tool to them we can easily monitor their daily production rate and compare it to their rate without the tool We feel very strongly that this design could reduce shoulder and hand fatigue by designing a tray large enough to rest their hands on as they simply slide the o rings Even if their installation times are slower than what we hope for we feel that reducing fatigue could keep employees more interested thus increasing daily production rates To reduce the o ring installment time for each o ring we plan to include o ring trays with our prototypes so that the range of motion between o ring placements 1s reduced By hand it took 35 seconds and with the fixture it took 54 seconds The main explanation for this is that the time trial was performed by capable individuals and there was no time lost in the handling of the o rings which is where S W Resource s employees lost most of their time 62 The time trial for this o ring resulted in 30 seconds by hand and 36 seconds using the fixture It s important to note that the o rings were picked up by hand and placed on the set piece rather than slid onto it because the current prototype does not have a cover This may be one reason for the increased ti
75. out hole in center of tray 18 Remove plastic from lexan and set on top of base Using a marking utensil mark out the four mounting holes to mount the tray Use an electric drill with 0 250 drill bit to drill the holes 19 De burr holes 20 Assemble tray and other parts based on assembly drawing The cost estimation for the medium O ring fixture is given in Table 9 2 2 1 Table 9 2 2 1 Cost Analysis for Medium O ring Fixture Cost Details for Medium O ring Fixture assembly line production Cut base per DWG Machine base per E hs 5 Machine guide per Final T5 M01 DWG 5 02 pe 13 5 02 REGES Overhead Factor Equipment Factor Special Operation Tolerance Factor Labor Overhead Equipment Cost Matenals Cost 9 2 3 Small O Ring Fixture The cost estimate for the Small O ring fixture is shown in Table 9 2 3 1 71 Table 9 2 3 1 Final Design Cost Analysis for Small O ring Fixture ui out top surface Drill holes and walls Cutrubber for screw on base Mill top laver cut inserts and mill out op stall t surface outholein feet install pocket on layer for layer for down mill er inserts and 1 base pocket pocket out slope a Total time to complete operation in Lex os os hours 0 25 0 5 c Labor Cost c d Basic overhead factor ER TE Equipment factor Spec
76. own time These sketches were based off original ideas that were influenced by previous patents and background research It was discussed as a team that all design sketches were beneficial and not to be criticized order to create a more open and positive brainstorming environment These sketches were presented during a team meeting allowing all concepts to be drawn on the board and discussed as a team so that all team members understood all of the concepts Each member asked questions about each concept to develop a general consensus of feasible designs At this point team members suggested modifications to each design In addition some concepts were integrated together to create one overall improved design The goal of this was to incorporate the best features of each concept into several suitable designs that would yield the best overall feasibility Most of the designs incorporated the use of a press mechanism There was a large variety of designs ranging from automated feeder systems to manual loading of the O rings Some of the designs installed multiple O rings at once Figure 4 4 1 and some installed one O ring at a time The second visit was planned and some of the designs generated from the brainstorming meeting were presented to SW Resources Our customer acknowledged our concept generation process and recommended that a final design would be suitable as long as their needs were met Another concept which we have considered is shown in
77. pect Ratio in Point Size in 4950 14322 6378 6 992 11483 33921 20421 7 197 01 26640 79920 65383 5 675 The loading and constraints can be seen in Figure 7 3 3 1 The mesh tested is 1 for an element side with 32 refinement points along the stress concentrations The refinement points have an effective radius of 1 inches with varying mesh sizes Refinement points Vx ray Constrained in Ty 2 250 Pd Figure 7 3 3 1 Loads and Constraints The reason for choosing these loads is to simulate a drop test By using the impulse momentum theory it was determined that for a height of 4 feet that the equivalent static load would be 99 4 Ibf so 100 Ibf was used The assumptions made were a time impact of 05 seconds and a weight of 10 165 for the fixture 46 Max Displacement 0215 inches Figure 7 3 3 2 Max Displacement As seen here in Figure 7 3 3 2 the max displacement for the finest mesh gave a displacement of 0 0215 inches The model shows the displacement times 500 This deflection is acceptable for the fixture because it will not cause significant failure to the part The wall that is deflecting 18 used to keep o rings from falling off the sides and the only effect the displacement has is that the part is not as visually appealing Given in Table 7 3 3 2 are the overall results for the three meshes followed by Figure 6 with the stress concentrations Table 7 3 3 2 FEA Results Refinement
78. perly try replacing the rubber bands 2 5 Replacement Parts Information 105 Part Part Material No Screws 4 10 24 12 Socket Lowe s Head Top Plate 1 Lexan Athens Glass 1 2 3 4 Rods 2 316 Stainless 5 Elastic Rubber Lowe s Bands 2 Guide 1 HDPE 106 Chapter 3 Small O ring Fixture Tip 3 1 Warnings and Safety Precautions WARNING Do not use this device in any manner inconsistent with the operating instructions given below WARNING Do not use any tool other than screw driver to perform maintenance troubleshooting Use of any other tool could damage the device A WARNING Do not use this device to install o rings with an outside diameter greater than 0 375 inches or less than 0 25 inches 107 3 2 Operating Instructions Follow these steps to install the small o ring onto the small tip part of the QCD Encore assembly 1 Deposit bag of small o rings onto top surface of the device 2 Slide one 1 o ring into the hole The o ring will now lie on the top surface of the rubber layer which is in the base 3 Pick up one 1 plastic tip part Verify that the part is inverted 4 Insert the plastic tip part into the hole on the top surface of the device 5 Press the plastic tip part into the rubber layer until the o ring has rolled onto the tip part 6 Remove the tip part from the device and verify that the o ring was installed correctly 108
79. r and lock nut to keep the nut from working loose during operation The platform was made to slide vertically within the pocket of the base forcing the part down onto the o ring and through the rods The part holder was added later and was absolutely crucial in maintaining proper part alignment with the rods during operation It contains a groove specially made to fit the geometry of the stem providing good alignment every time corners on the part holder were machined with a quarter inch radius to make the device comfortable and easy to use The rods are the installation mechanism They were chosen to be 303 SS to meet the target specification of daily cleaning Grooves were cut into the rods to provide a seat for the rubber bands We found through testing that this reduced the friction between rubber bands and HDPE allowing the rods to properly expand as the part is pushed between them 64 Figure 8 0 3 CAD Model of Large O Ring Fixture 9 0 Final Design for Production 9 1 Design Description and Operation The following sections describe the design and operation of each of our fixtures For more details the User Manual is included in Appendix E and our technical engineering drawings are included in Appendix F 65 9 1 1 Large O Ring Fixture Figure 9 1 1 1 CAD Model of Large O ring Fixture The design for the large o ring fixture can be seen in Figure 9 1 1 1 Its operation is to install an O ring onto a specific part
80. referred to as the stem The stem has an odd shape and required a slightly different design The base function utilizes two stainless steel rods held in tension by rubber bands The rods in tension apply pressure to the head of the stem As the stem head is forced through the rods the o ring is forced to slip around the head of the stem See the User s Manual for proper operating instructions and safety precautions As found in Figure 9 1 1 1 the main components of the design are highlighted for these components be found in the Appendix Number T is the base Number 2 1s the platform Number 3 15 the part holder 4 1s the angled top Number 5 15 the tray For simple operation the user would slide an o ring from the tray into the preferred slot on the platform Then the user would install a part into the part holder The user would then press down on the part holder forcing the o ring to slip around the part as the rods expand around the stem head This is summarized in Table 9 1 1 1 66 Table 9 1 1 1 Component Parts of Large O ring Fixture Part Description HDPE Base HDPE Platform HDPE Stem Holder HDPE Inclined Rod Base Lexan Part Tray 9 1 2 Medium O ring Fixture Figure 9 1 2 1 shows the final CAD model design for the Medium O ring fixture Figure 9 1 2 1 Solid Model of Medium O ring Fixture Final Design Like the large O ring fixture 15 operation 18 to install an o ring onto a specific part
81. rity SEV When the o ring 18 not installed properly this means that the worker must repeat the procedure in order to install the o ring But no harm is done to the user If the devices consistently do not install the o rings then the device 1s practically inoperable 2 Include some discussion justification for the rating for probability of occurrence OCC Our first prototypes and mockups were inconsistent in their performance However later on in the design process they were much better 3 Include some discussion justification for the rating for probability of detection DET It would be fairly easy for the workers to detect whether or not the o ring was successfully installed This procedure would be no different than the procedure they currently use for the hand installation 4 Recommended actions to achieve acceptable risk Make specific recommendations for action and include some discussion of the alternatives that were considered the person s responsible for completing the actions and the completion date Refine the designs to reduce the required input force This appears to be a major cause for this type of failure 5 Notes on Completed Actions 88 Potential Failure 2 Fracture of the o ring Operating mode when failure could occur Potential Failure Mode Operation Text here Initial After Action Evaluation PLA LL Potential Cause s Mechanism s of Failure o of occurrence OCC Current Cont
82. rols M s Coi Rc Boso Detection and Prevention Probability that failure is detected and prevented DET Risk Priority Number RPN SEV OCC DET 1 Include some discussion justification for the rating for severity SEV Fracture of the o ring would render the product unusable and would incur material cost to the customer but no one would be harmed by this failure 2 Include some discussion justification for the rating for probability of occurrence OCC We do not think this failure 1s likely since no sharp edges are incorporated in the design which could cause the o ring to fracture Potential Effect of Failure Severity SEV 3 Include some discussion justification for the rating for probability of detection DET It would be easy for a worker without disability to detect this failure but we are not sure if any of the employees with disabilities would necessary be able to consistently detect this failure mode 4 Recommended actions to achieve acceptable risk Make specific recommendations for action and include some discussion of the alternatives that were considered the person s responsible for completing the actions and the completion date We will perform FEA on the o ring to determine if normal operating conditions would cause this type of failure 5 Notes on Completed Actions Potential Failure 3 Fatigue in the rubber sheet Operating mode when failure could occur Potential Failure Mode Operation cleani
83. s if any with this device Do you feel that you would use this device in the future Explain How could the design for this device be improved Additional comments 96 Appendix User s Manual QCD ENCORE O ring Installation Fixture User Manual 977 Chapter 1 Large O ring Fixture Stem 11 Warnings and Safety Precautions Dropping fixture from large height s may result in damage to the fixture Keep fingers above stem platform to avoid pinch points 1 2 Operating Instructions 1 Place o rings and or stems onto the tray 2 Employee slides an o ring down the slide until the o ring sits into the groove marked with red 3 Load the device completed by sliding a stem into the part holder as shown 4 The employee then pushes straight down on the stem holder allowing the stem to slide through the rods applying the o ring 5 While holding the knob down the stem is removed by using a finger and sliding it out of the holder 99 1 3 Suggested Maintenance Schedule and Instructions A Replacing the rubber bands Use a 5 32 Allen Key wrench to loosen the tray and tray brace 5 bolts Remove rods 2 from base 2 Remove rubber bands from rods and install new bands Replace the rods back into position and reinstall the tray and mounting bolts 14 Troubleshooting and Service Instructions 1 If the fixture is not functioning properly try replacing the rubberbands
84. s for design initial thoughts of complex systems such as automatic vibratory feeders and hand presses were mentioned After doing research on a company by the name of Whitney Systems Inc in Chelmsford MA 6 we found that these systems Figure 4 2 1 would be too costly noisy and may eliminate the actual job of a worker A more simplistic design was necessary D WhibneySystems com Figure 4 2 1 Automatic O Ring Feeder and Press Some of our concept ideas were influenced by OTB Designs amp Engineering LLC 5 In Figure 4 2 2 there is an O ring that is slid into a cavity of a platform The part is then pressed down by hand to insert the O ring in the inside of the part The simplicity and effectiveness of this design has given much insight into the types of concepts we may generate and provides an alternative to automatic feeders and presses 12 Figure 4 2 2 OTB Designs amp Engineering 4 3 Applicable Patents Listed below are some of the patents that we felt were applicable to the design process For each patent there is a description of how the device works as well as what was learned from that design Patent 1 O Ring Insertion Tool 7 Patent number 4141129 Filing date Sep 27 1976 Issue date Feb 27 1979 Inventor Leonard J Martini 13 SM 2222222 SW 22 EAT SER Na 121 7
85. ses in analysis no testing Device cannot be operated Good information no 50 chance of detection 5 by user no danger to user operating experience and avoidance minimal testing design We identified seven specific failure modes for our design 1 incomplete installation of O ring 2 O ring fracture 3 fatigue failure in the rubber sheet 4 corrosive wear of the fixture 5 harm to user due to sharp edges 6 bending in metal O ring feed tray and 7 stripping of threads in plastic base We then obtained the RPN by computing the product of the numerical rating for each of the three factors Those failure modes with the highest RPN would receive particular attention for corrective actions or testing Table 7 1 2 summarizes the results of our FMEA analysis the actual FMEA worksheets which were used to obtain these results are included in Appendix C 3 Table 7 1 2 Summary of Initial FMEA Results Severit Probability of Probability Risk Priority Failure Mode S Yl Detection RPN S O D 7 9 7 2 Fracture of O rins 6 2 7 8 3 Faigueinrbber 8 3 4 96 4 consion du to deaning 7 2 2 5 Sharp Edges 1 9 6 Bending in o ring feed way 7 77 Swipping ofthreads 8 3 6 m 8 Erare 7 1 7 From the results presented in Table 7 1 2 we determined that the failure modes which needed speci
86. slightly over 7 Ibsf The input force though is less than half of the maximum required force we determined for our fixture therefore the large O ring fixture test indicates that our design met this technical specification Preliminary input force data for the medium O ring fixture is given in Table 7 5 1 2 Table 7 5 1 2 Medium O ring Force Data Preliminary Results Input Force Testing 4 wraps of rubber Input Force Testing 3 wraps of rubber band band 60 222 60 X 0 O 80 tH 90 128 90 16 O 29 Our preliminary results for the medium o ring Table 7 5 1 2 show how the input force is affected by ranging the rubber bands elastic constant thus the number of wraps of the band Having four wraps the maximum input force was 23 4 pounds An average force over ten trials is 17 6 pounds With 3 wraps the o ring continued proper installation and the input force decreased The maximum input force was 15 2 pounds with an average force of 13 55 pounds From our results we see that the force to install the medium o ring exceeds our target specification of 10 pounds To address this we plan on furthering our experimentation by performing tests with different elastic bands so that the o rinz tnstattation is successful having an average input force of approximately 10 pounds Our final force tests for the medium fixture show how the input force varies with time in Figure 722 425 Force vs Time d
87. t Socket Lowe s Head Glass 4 Bands 2 77 Guide 1 HDPE Spring 1 Stainless Steel 75 9 3 3 Small O ring Fixture The Parts List and Bill of Materials for the small O ring fixture are given in Table 9 3 3 1 and Table 9 3 3 2 respectively Table 9 3 3 1 Parts List Item Document 15 5 001 12 x12 x1 HDPE 1 2 T5 S 003 Rubber 1 8 Natural Latex 1 Rubber T5 S 004 Top Cover 1 8 HDPE 1 2251 0201 Screw 1 K1 8 Stainless Steel Table 9 3 3 2 Bill of Materials Quantity Supplier 25 80 86395 22 12 x2 x1 16 Stainless Steel 10 29 6 32 Brass Inserts 2 68 6 32 SS Screws 5 37 10 0 Conclusions The objective of this project was to develop a system or device that would assist and increase production of installation of three different sixed O rings onto three different parts with unique geometries We determined to create three unique designs to assist with the installations of these three O rings Although some features are similar across designs each of the three designs we generated are distinct With reflection back to the Hierarchal Customer Needs List in Table 2 2 2 many of these needs were met with this design Safety of the worker was a constant consideration with this project All three devices are safe to use although the Large O ring fixture does have a couple of possible pinch points However we have deemed the r
88. t we determined that a comfortable force would be 2 3 of this maximum force Thus the target value for the input force 1s 15 Ibsf for the medium and large fixtures Since the input force for the small o ring fixture 1s applied over an extremely small area only a fraction of the surface area of a single thumb we determined that our target value should be 5096 of the maximum force Thus the target value for the small fixture is 11 Ibsf The insertion force will be much greater than the extraction force however only one design will have an extraction force The experiment involves placing an o ring into to its appropriate slot and then taking the o rings respective part and pressing it into the fixture The input force will be measured during the pressing process This experiment is relevant to the overall design and satisfaction of the customer because it will help to determine whether the design is capable of meeting the customer requirements as well as improving their process If the force is too large changes or adjustments must be made to the design The following procedure was used to conduct this input force experiment Calibrate force sensor 54 522 6 Connect force sensor to plastic part Place fixture on platform Set the o ring in the stop on top of the fixture Place the part on top of the o ring and press down on the part until the part pushes through the rods and the o ring is in place Repeat steps 1 5 until suf
89. t through the bars during the assembly Displacement Magnitude in 0 08551614 0 08075904 0 07600193 0 07 124482 0 06648772 0 06173061 0 0569735 0 0522164 0 04745929 0 04270218 0 03794508 TIMES 12175 Time Step 5 075 Maximum Value 0 0855161 in 0 147 in 0 203 0 440 Minimum Value 0 0379451 in NUM Figure 7 3 2 Elastic Band Displacement 22 Stress von Mises 52 433 4965 392 0653 350 6341 309 2028 267 7716 226 3404 184 9092 143 4778 102 0467 50 651547 19 18424 Time 0 1 5 Time Step 5075 Maximum value 433 497 Ibf in 2 0 0 147 in 0 293 0 440 Minimum Value 19 1842 Ibf in 2 Figure 7 3 3 Elastic Band von Mises Stress 7 3 1 FEA for Large O ring Fixture The first failure scenario we investigated specific to the large O ring fixture was the dislodging or torquing of the platform inside of base This platform moves in the fixture when the user places the stem part onto the platform and presses down to install the large O ring The geometry of this part is shown in Figure 7 3 1 1 36 aT Figure 7 3 1 1 Geometry of Platform The materials of which this part is made of is HDPE injection molded which has an average tensile yield strength of 3773 psi For this analysis an edge force was applied in the Y direction with a force of 20 Ibs at the beginning of the radius on the flange The three edges with circles were constrained using a pinned constraint Th
90. time a constant emphasis was placed on design feasibility With respect to our project the most simple cost efficient and productive design would be the most feasible Simple 18 in regard to the operation of the design A target specification of O ring application was determined by the group to be achieved in less than 3 steps Cost efficient 1s in reference 19 to the total cost that would be included in materials and manufacturing Productive is in terms of how effective the operator would be while using the design With these criteria in mind designs continued to be worked on and a total of 4 designs were chosen to be potential final concepts Figures 5 1 1 5 1 2 5 1 3 and 5 1 4 contain the sketches of the four concepts Figure 5 1 1 Design Concept 1 20 TT TEN PVT PARI ao lt El ae c NR TS SOFT PLASTIC RR KLOR LAO RING A 606 0 T 7 pes D n x e 1 ae E Figure 5 1 2 Design Concept 2 Figure 5 3 1 Design Concept 3 21 TNPUT HOLDING 2 PEATURE f Figure 5 1 4 Design Concept 4 Based on the criteria developed for feasibility and effectiveness each of the 4 concepts accomplishes each respective goal With a working budget of about 300 there is sufficient funding available to build 3 separate fixtures one for each O ring assembly based on the vo
91. to accomplish the task of O ring assembly so that we could accurately identify the specific need of the customer However since SW Resources has not to date begun the actual assembly and installation of the O rings for the syrup dispenser we could only observe and collect data based on their proposed methods Thus any data which we have collected thus far for worker productivity levels is tentative and is only a crude estimate The data we collected on worker productivity is included in Appendix Figure 3 0 1 shows the proposed floor layout plan for the O ring installation According to this plan all three O rings are to be assembled at separate stations Once the O rings are installed on each of the three parts the parts are sent to a station where the entire syrup dispenser is assembled This plan proposes that the method for installing O rings is purely manual The O rings and the parts are provided to the employee by a supervisor The O rings and parts are initially in separate containers and it is the task of the employee to take both out of their respective containers install the O ring manually while holding the part and to deposit the part with the installed O ring into a part bin which will transport the part to the final assembly stations PSA PRODUCTION FLOOR PLAN LAYOUT 112 EDDY 4 PARTE 1 5 or FING PARTE STAGED iD TR E L PARTS STAGED
92. urces SW Industries available at http www swresources com html industries html accessed on November 11 2008 US Census Bureau 2006 American Community Survey available at http www census gov hhes www disability 2006acs html accessed on November 11 2008 OTB Designs amp Engineering LLC O Ring Installer http www otbdesigns com Product ORing 20Installer prod_ORing htm accessed on November 4 2008 Whitney Systems Inc O Ring Installation http www whitneysystems com O Ring Installation 5 htm accessed on November 6 2008 Martini Leonard J O ring insertion tool US Patent No 4141129 Feb 27 1979 Available at http www google com patents idZAcEwA AAAEB AJ accessed on November 16 2008 Whetstone Merle A seal O ring insertion tool US Patent No 6012209 Jan 11 2000 Available at http www google com patents id _dIAAAAAEBAJ amp dq 6012209 accessed on November 16 2008 Zannini Frank O ring insertion tool US Patent No 5050282 Sep 24 1991 Available at http www google com patents id Kn YdAAAAEBAJ amp dq 5050282 accessed on November 17 2008 NISH NISH National Scholar Award available at http www nish org NISH Rooms DisplayPages LayoutInitial Container com webridge enti ty Entity SbOID 5bBC73236A9D14A34683503284C295572D 5d 5d accessed November 17 2008 Kremer Greg Program Educational Objectives Statement available at http ww
93. urces Date Sept 18 2008 Brent Morris and Jonathan Robe met with Kellie Conrad to discuss possibly working with SW Resources for the Senior Design project We toured the facilities of SW Resources to observe the different project opportunities that we would have if we selected them to be our customer The different projects which Kellie listed as options for us to consider are the following 1 Widget Project with DuPont assembling a fountain drink machine syrup dispenser with O rings 2 Installing Braille beads onto room signs inserting the Braille beads into drilled holes in the sign 3 letter folding department folding letters and inserting them into envelopes SW does have a paper folding machine which they already use for this 4 bagging nails and screws they will be getting a machine soon to do most of this task 85 Observation Notes from Meeting with SW Resources Date October 8 2008 We visited SW Resources with the goal of meeting and observing some of the employees who will be participating in the O ring assembly project The information that we gathered from our visit included all parts including the 3 different sized O rings were in separate bags all of the parts were loose inside each bag electric outlets were available in the workspace large tables 4 ft x 10 ft with chairs were in the workspace Some tables were plastic According to SW managers the assembly of each O ring was to occur at differ
94. w ent ohiou edu kremer ChairStuff PEOs_modifiedSpring2007_approvedSpringO 8 pdf accessed on November 17 2008 ISAHP ISAHP 2009 Symposium July 29 August 1 2009 Pittsburgh Pennsylvania USA available at http www isahp org accessed on November 15 2008 E mail from Kellie Conrad of SW Resources to Brent Morris September 23 2008 79 14 Stamatis D H Failure Mode and Effect Analysis FMEA from Theory to Execution Milwaukee Wisconsin ASQ Quality Press 1995 15 Kremer Greg Design FMEA Failure Mode and Effect Analysis available at http www ent ohiou edu me470 SnrDesign05_06 me47 1 FMEA amp Reliability06 pdf accessed on May 20 2009 16 Zatsiorsky Vladimir M Kinetics of Human Motion Human Kinetics Champaign IL 2002 80 Appendix A Data on Disabilities in the United States Table A2 DISABILITY STATUS OF THE CIVILIAN NONINSTITUTIONALIZED POPULATION 4 lt i Population 5 years and over 273 835 465 21 234 With a disability 41 259 809 98 726 Population 5 to 15 years 44 696 789 40 535 With a disability 2 829 622 32 313 Population 16 to 64 years 193 568 216 43 195 With a disability 23 863 097 85 217 Population 65 years and over 35 570 460 18 433 With a disability 14 567 090 42 335 51 Table A2 PERCENTAGE OF CIVILIAN NONINSTITUTIONALIZED POPULATION 21 TO 64 YEARS OLD WITH A DISABILITY BY STATE STATES RANKED 1 30 4 6 Oklahoma 140
95. yer when it wears out The main positive outcome for our designs for the Large O ring fixture 1s that they reduce the amount the tactile handling of the parts This was a problem for the workers due the rough edges of the parts wearing out the user s hands The main negative of the design is that there is no automatic ejection of the part after the o ring 15 installed The users have difficulty removing part with their hands If an ejection was incorporated the productivity and user friendliness would increase At this point the fixture does not increase user production time initially Over time the reduction in handling may improve worker production due to soreness in the hands from handling the part The Medium O ring fixture however did increase the physical discomfort of users certain circumstances Users of the Medium O ring fixture indicated that their hands would become sore after repeatedly operation This problem could easily be solved if the users were given padded palm gloves when they operate the fixture This is something which should be included with any of these fixtures manufactured in the future Our customer feedback indicated except for this problem the customer was pleased with this fixture though we do not know to date whether the customer would order more of this design We have concluded based on customer feedback that the Small O ring fixture did not successfully assist the users in installing O rings The users

Final Design Report

Contents

Download Pdf Manuals

Related Search

Related Contents