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User's Guide to Plastic

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1. o ooomoo oo 117 21 Material Selection PO an Mean ani aan san 127 22 Requirements and Specification for Plastic Products oooo oom 131 23 Design Rules for Thermoplastic MOIINGS cccccecceecceeceeceeeeeeeeeeeeeeeeaeeeeeeaeeeaees 145 24 Assembly Methods for Thermoplastics Wo ooo on 159 25 The Injection Molding Proce ooooooWo oom WWW W WWW man 165 26 Injection Molding Process Parameters ooo WoWo Wo Woo mma 183 2 Problem Solving and Quality Management oo Wo WWW oo Wo WWW ma 185 28 Troubleshooting Causes and Effects o WoooWo W WWW Wo oom Wa 195 29 Statistical Process Control OIC eni ale Ben an Ba Ab Sae baba on 215 OO Internet Links CHING Xi ee en ta 223 Foreword For many years have had the idea of writing a book about injection molding as have spent over 45 years of my working life on this subject When retired in 2009 was given great support by my friends Katarina Elner Haglund and Peter Schulz of the Swedish plastics magazine Plastforum who asked me to write a series of articles about thermoplastics and their processing for the magazine was also hired at this time to work with educational programs at the Lund University of Technology the Royal University of Technology in Stockholm and a number of industrial companies in Sweden as a result of which this book was developed My aim has been to wri
2. Plastic products enable energy savings equivalent to 50 million tons of crude oil that s 194 very large oil tankers Plastic prevents the emission of 120 million tons of greenhouse gas emissions per year which is equivalent to 38 of the EU s Kyoto target The average consumer causes around 14 tons of carbon dioxide emission Only 1 3 of that about 170 kg is derived from plastic In the automotive and aerospace industries the use of plastic saves weight and thus reduces fuel costs In the construction industry plastic is increasingly used as a superior insulation material that provides a good indoor environment and reduces energy consumption Fig 112 Plastic accounts for approx 12 15 of a modern car s weight which in Europe alone results in annual savings of 12 million tons of oil and a 30 ton reduction in CO emissions The body of this sports car is made of carbon fiber reinforced plastic and has an even higher proportion of plastic than an ordinary car Without plastic transportation costs for the retail industry would increase by 50 On average plastic packaging accounts for between 1 and 4 by weight of all products packaged in plastic For example a film that weighs 2 g is used to pack 200 g of cheese and a plastic bottle weighing 35 g packs 1 5 liters of drink If you also include containers and shipping material then plastic packaging increases its share to 3 6 on average Fig 113 A 330 ml glass Coca Cola
3. AB Stebro Plast AB Talent Plastics AB Celanese Tojos Plast AB Vadstena Lasermarkning Weland Medical AB Internet link www acron form se www ad manus se www ad plast se www arkema com www arlaplast se www artaplast se www bergoflooring se www clariant com www digitalmechanics se www distrupol com plastics dupont com www dsm com www dst se wwwelastoteknik se www engelglobal com www erp se www en european bioplastics org www ferbe se www flexlink com www hammarplast se www hordagruppen com www imcd se www injection mold info www ikem se www kdfeddersen com www makeni se www mapeplastics se www se mt com www miljosack se www nordicpolymers dk www novamont com www plastinject se www polykemi se www polymerfront se www polyplank se www protech se www res se www resinex se www rotationsplast se www sematron se www stebro se www talentplastics se www celanese com www tojos se www lasermarkning se www weloc com Product or service Rapid prototyping Training testing analysis Injection moldings Plastic raw material Extrusion Injection moldings Plastic flooring Masterbatch Rapid prototyping Plastic ddistributor Plastic raw material Plastic raw material Electro optical systems Thermoplastic elastomers Injection molding machines Plastic distributor European trade organization Tool maker Conveyors Storage products Blow moldings Plastic distributor Mold graphics Swedish trade organizatio
4. All materials in this group can be recycled and they have the material abbreviation in square brackets e g gt PTFE lt as their recycling code 33 Chapter 6 Bioplastics and Biocomposites Definition If you ask a professional what is a bioplastic you would get one of three different answers 1 It is a plastic manufactured from biologically based raw materials 2 It is a plastic that is biodegradable i e can be degraded by microorganisms or enzymes 3 It is a plastic that contains natural fibers Since biobased plastics are not necessarily biodegradable and biodegradable plastics do not have to be biobased it is important to be clear about what you really mean The percentage of renewable ingredients necessary for a plastic to be considered bio has not been established although leading bioplastic suppliers deem that it should be at least 20 Plastics containing natural fibers are also called biocomposites and are mostly traditional plastics that have been reinforced or Fig 95 Some of the first thermoplastics were blended with natural fibers such as wood flax Shiha ale from pate but they dead ave little commercial significance except for hemp a cellulose ne viscose fiber Ping pong balls were originally In addition to the commodities PE and PP made of celluloid and are still produced from there are also biopolyesters such as PLA cellulosic materials What do we mean by Bioplastic Bi
5. Method solution of formic acid of 2 45 erom mpe per which is well within the Ash 299 28 0 32 0 ISO 03451 Relative viscosity 245 220 2 60 DSM Method 90 HCOOH tolerance limits 67 Chapter 12 Injection Molding Methods History Injection molding is the predominant processing method for plastics allowing the production of parts in both thermoplastics and thermosets In this chapter however we focus on injection molding for thermoplastics The method was patented in the U S back in 1872 by the Hyatt brothers who began producing billiard balls in celluloid The first molding machines were piston machines where the plastic material was filled in a heated cylinder Once the plastic is thus melted it is pressed into a cavity by means of the piston The first screw machines i e the type used today were not introduced until the 1950s Injection molding has become the most popular machining process for thermoplastics today because it provides such great cost advantages over conventional machining or other casting methods The process has also undergone great development in the last fifty years and is now completely computerized Fig 194 The picture shows an old piston Fig 195 A modern injection molding machine injection molding machine The locking manufactured by Engel This machine has a mechanism was a knee joint type that is hydraulic locking mechanism You can also get commonly used even today but the locking
6. material contained herein Disclaimer We have done our best to ensure that the information found in this publication is both useful and accurate However please be aware that errors may exist in this publication and that neither the author nor Bruder Consulting AB guarantee the accuracy of the information All the tradenames and registered trademarks occurring in this book are for identification purpose only and are the property of their respective owners The final determination of the suitability of any information for the use contemplated for a given application remains the sole responsibility of the user Cataloging in Publication Data is on file with the Library of Congress Bibliografische Information Der Deutschen Bibliothek Die Deutsche Bibliothek verzeichnet diese Publikation in der Deutschen Nationalbibliografie detaillierte bibliografische Daten sind im Internet Uber lt http dnb d nb de gt abrufbar All rights reserved No part of this book may be reproduced or transmitted in any form or by any means electronic or mechanical including photocopying or by any information storage and retrieval system without permission in writing from the publisher Carl Hanser Verlag Munich 2015 Editor Mark Smith Production Management J rg Strohbach Coverdesign Stephan R6nigk Printed and bound by Offizin Andersen Nexo Leipzig Germany ISBN 978 1 56990 572 2 E Book ISBN 978 1 56990 573 9 Table of Contents Kore Or na De
7. the figure below to the right Fig 253 A less viscous grade of acetal Fig 254 By applying a pattern of flow with slightly less impact resistance was directors one succeeded to fill the chosen to fill the fan shroud entirely shroud without getting the flash in the but still flash in the middle could not be middle nor did the cycle time need to avoided be extended 93 Chapter 17 Prototype Molds and Mold Filling Analysis In the previous chapter we described various errors that depend on either an incorrect part or mold design When designing new parts or starting the molding of a new product you will get a number of new questions and challenges Will the part get the correct dimensions Will it warp Are the runners too long Will the part be completely filled Where should the gate be placed in order to make the part as strong as possible Are the temperature control channels correctly dimensioned and located Prototype Molds In order to avoid unpleasant surprises when starting the production in a new mold you can use a prototype mold to see what the part would look like once it has been molded Another option is to complete only one of several cavities in a production mold These procedures could save both money and time But they are not always completely reliable as runners and mold temperature systems seldom correspond to the final production mold Producers are using prototype molds when the plastic part is very co
8. unmodified standard grade of the polymer in guestion and serve only as a rough guide Contact your plastic raw material supplier for accurate information about your specific grade The melt temperature is one of the most important parameters When processing semi crystalline plastics you should always consider the risk that you may get unmelted granules in the melt To eliminate this risk you should use the cylinder temperature profile that depends on the capacity utilization of the cylinder See Chapter 25 page 171 You should also be aware that additives such as flame retardants or impact modifiers often reguire a lower temperature than the standard grade Glass fiber reinforced grades should have as a rule the same temperature settings as unreinforced grades The mold temperature is also one of the most important parameters for achieving the best quality For semi crystalline plastics you need a certain temperature to ensure that the material s crystal structure will be correct and thus provide the best strength and dimensional stability less post shrinkage See Chapter 25 page 173 Drying is needed for plastics that are either hygroscopic absorb moisture or sensitive for hydrolysis degraded chemically by moisture See more in Chapter 25 page 170 We recommend that molders use dehumidifying dry air dryers in their production Therefore we publish both the temperature and drying time needed to be below the maximum allowed moisture co
9. will cover different types of molds and in the next chapter we will look at them in more detail If you ask an operator within the molding business what types of molds are commonly used their likely reply is common molds and hot runner molds Hot runner molds will be discussed in the next chapter What the operator probably means by common molds is shown below e Conventional two plate molds e Three plate molds e Molds with slides e Molds with rotating cores for parts with inner threads e Stack molds e Molds with ejection from the fixed half e Family molds e Multi component molds e Molds with melt cores The list covers most of the common types of molds but does not claim to be complete In most of the above types you can also choose between either cold or hot runner systems for the molds Two Plate Molds Two plate molds are the most common type of molds for injection molding Fig 223 Here is an example of a two plate mold with one cavity used to manufacture the basket shown in the picture at the top left corner It is easy to see that the right half is the movable one since the ejector plate bottom can be seen here The left half is fixed and has a hot runner system integrated The four columns are used to center the mold halves together 81 Chapter 15 Structure of Molds In this chapter we will focus on how a common two plate mold is constructed We will look at the following A The function of the
10. 0TL NC000 Stress at break ISO 527 1 2 C Delrin 107 NC010 Strain at break ISO 527 112 C Delrin 111P NC010 C Delrin 127Uv NC010 C Delrin 150 NC010 C Delrin 150XV NC010 Charpy impact strength 23 C ISO 179 1eU CO Deirin 300CP NC010 Charpy impact strength 30 C 2 ISO 179 eU al 1 Charpy notched impact strength 23 C z ISO 179 1eA Tensile creep modulus 1h ISO 899 1 Tensile creep modulus 1000h ISO 899 1 File View Window File Diagram Window SR BBw esi tO R a on Product text E Viscosity Data 2 Common features of Delrin acetal resin include mechanical and physical properties such as high T mechanical strength and rigidity excellent fatigue and impact resistance as well as resistance to moisture gasoline lubricants solvents and many other neutral chemicals Delrin acetal resins also have excellent dimensional stability and good electrical insulating characteristics They are naturally resilient self lubricating and available in a variety of colours and speciality grades The good melt stability of Delrin acetal resin normally enables the recycling of properly handled production waste If recycling is not possible DuPont recommends as the preferred option incineration with energy recovery 17 kJ g of base polymer in appropriately equipped installations For disposal local regulations have to be observed Delrin acetal resin typically is used in de
11. DuPont Properties of Polyamide Stiffness at high temperatures glass fiber reinforced PA High service temperatures 120 C constantly and a short term peak Mechanical Properties DAM Cond Unit MPa _Tensile stress at yield 82 53 MPa Elongation at yield sop 45 25 Charpy notched impact strength 39 5 5 15 kJ m Charpy notched impact strength 30 4 5 3 kJim Fig 44 This table shows the mechanical properties temperature of 180 C Good electrical properties Food approved grades are available Can be made flame retardant Absorbs excess moisture from the air which alters the mechanical properties and dimensional stability Brittleness at low temperatures if not impact modified of a standard quality of PA66 in a DAM Dry As Molded unconditioned state and after the material has absorbed 2 5 humidity at 23 C and 50 rel humidity conditioned state The stiffness decreases by 65 and tensile strength by 35 while toughness elongation increases five fold The impact strength at room temperature increases three fold but drops by 33 at low temperature Source DuPont 19 Chapter 4 Thermoplastic Elastomers Thermoplastic elastomers TPE are soft thermoplastics with a low E modulus and high toughness Also called thermoplastic rubbers their toughness is sometimes indicated by Shore A or Shore D to characterize them as with rubber Their chemical structu
12. Electron microscope Elongation at yield Environmental impact Extrusion z Factorial Failure definition Failure mode effect analysis Family mold Fill rate Film blowing Flammability Flammability test Flash Flexural modulus Fluoroplastic FMEA G Gas bubbles Gas injection Gate Gate design Glass fiber streaks Glass transition temperature Gluing Goal value centering Granulation 147 181 179 41 145 186 199 198 180 179 170 172 44 H HB classification HDPE Heat deflection temperature Heat stabilization High performance nylon Hold pressure Hold pressure switch Hold pressure time Hold up time Hot air dryer Hot channel mold Hot plate welding Hot stamp printing Hygroscopic IMD Impact strength Injection molding cycle Injection molding economics Injection molding failure Injection molding machine Injection molding methods Injection molding process Injection pressure Injection speed Injection time Injection unit IR spectrophotometer IR welding Isotactic Izod J Jetting L Laser marking Laser welding LCP LCPA LDPE LLDPE Locking unit Lot number M Machine capability Masterbatch Material data Material Data Center Material selection MDPE Mean value Mechanical properties Melt core mold Melt index Melt temperature Melting point Metalization Microtome cut Monomer Mold Mold failure Mold filling simulation Mold shrinkage Multi component i
13. Fig 522 Forms for the analysis of problems in Excel format are available at www brucon se We will now describe a wide range of common and uncommon errors that can occur during the injection molding process We have also tried to list the causes of the most probable ones in a logical order based on a large number of troubleshooting guides issued by leading plastic suppliers NOTE When troubleshooting it is important that the material supplier s process recommendations for the relevant material are available to adjust any incorrect settings 195 Chapter 29 Statistical Process Control SPC Statistical process control is a method that has long been used in the engineering industry to improve the guality of produced products Regarding the production of plastic products it has not yet been put into use on a large scale 2014 SPC among molders is however largely increasing In this chapter we will give the reader an orientation on the principles and different concepts used This chapter has been developed together with Nielsen Consulting www nielsenconsulting se a Swedish consultant who specializes in SPC training and has contributed with text and images Why SPC SPC is a very useful and profitable method because it e Creates customer value i e improves the function or extends the lifetime of the customer s product e Reduces rejects by focusing on the tolerance center see terms below instead of the tolerance limits e Pr
14. HANSER Sample Pages UIf Bruder User s Guide to Plastic Book ISBN 978 1 56990 573 9 For further information and order see www hanserpublications com in the Americas www hanser fachbuch de outside the Americas Carl Hanser Verlag Munchen Ulf Bruder User s Guide to Plastic Ulf Bruder User s Guide to Plastic A handbook for everyone HANSER Hanser Publishers Munich Hanser Publications Cincinnati The Author Ulf Bruder Bruder Consulting AB Barkassgatan 9 SE 371 32 Karlskrona Sweden Distributed in North and South America by Hanser Publications 6915 Valley Avenue Cincinnati Ohio 45244 3029 USA Fax 513 527 8801 Phone 513 527 8977 www hanserpublications com Distributed in all other countries by Carl Hanser Verlag Postfach 86 04 20 81631 Munchen Germany Fax 49 89 98 48 09 www hanser fachbuch de The use of general descriptive names trademarks etc in this publication even if the former are not especially identified is not to be taken as a sign that such names as understood by the Trade Marks and Merchandise Marks Act may accordingly be used freely by anyone While the advice and information in this book are believed to be true and accurate at the date of going to press neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made The publisher makes no warranty express or implied with respect to the
15. a description of the product and its intended usage and is often defined by the following questions Have we developed a similar product What new features will the product have Is this just a new size upscaling downscaling of an existing product Can we modify the geometry of an existing product to create this new one Does the new product require a radical change of materials How do the competitors products work What tests studies or reports already exist regarding this type of product Fig 356 The picture on the left shows a zinc cam furniture assembly screw The cam in the picture on the right has the same dimensions but there has been a radical change to the material used i e polyamide instead of zinc Fig 357 The picture above shows various sealing clips Working from the left clips 3 to 6 are purely upscaled downscaled versions of the same product whereas the other three clips have different geometries Fig 358 When collecting background information for the development of a new product it is common to compare existing products on the market to try to find possible improvements new functions or lower production costs than your competitors 131 Chapter 23 Design Rules for Thermoplastic Moldings Designing in plastic is a science in itself and a lot has been written on the subject This chapter aims to show some of the most important rules that a designer should bear in mind when developing
16. a mold with a simple parting line The halves are then rotated 90 in relation to each other and then joined together by press fitting Assembly Methods That Facilitate Disassembly Among the dismountable methods the following methods are usually used when it comes to plastic details e Self tapping screws e Threaded inserts e Screw joints with an integrated thread e Snap fits specifically designed to allow disassembly Fig 434 If a good screw joint is required for a self tapping screw the plastic material should have a B A SNEED Tower Trai A000 Ma a Fig 435 and 436 Above to the left is a threaded brass the same as for POM For stiffer bushi in th IL of housi de 4 materials e g glass fiber rein Re en aa Gani reinforced polyamide 66 The bushing can either be over tareea a ACSC Moe Or ne Saden molded or pressed into the plastic wall inserts are recommended It is also important to use a self tapping screw The plastic caps on the plastic bottles in the picture to the that is specifically developed for right are typical examples of a screw joint with integrated plastic materials threads 159 Chapter 25 The Injection Molding Process Molding Processing Analysis In this chapter we will go through the main injection molding parameters that affect the guality of the moldings We will also emphasize the value of working systematically and having good documentation To the right there is a do
17. a new product in plastic These rules are divided into the following ten sections 1 Remember that plastics are not metals 2 Consider the specific characteristics of plastics die 3 Design with regard to future recycling ERR RENT PEP te 4 Integrate several functions into one component PEE iil ik dina 5 Maintain an even wall thickness 6 Avoid sharp corners 7 Use ribs to increase stiffness 8 Be careful with gate location and dimensions 9 Avoid tight tolerances 1 0 Choose a suitable assembly method Fig 393 There is some good design literature online available for free download One such document is General Design Principles for DuPont Engineering Polymers containing 136 pages of useful information See plastics dupont com plastics pdflifamericas general H76838 pdf Rule 1 Remember That Plastics Are Not Metals Some engineers still design plastic components as if they were made of metal If you can succeed in maintaining the strength the product will be lighter and often much cheaper However if the main purpose is to reduce production costs it is by default necessary to make a total redesign when plastic is intended to replace metal If a direct comparison is made the metal will have a higher Density Maximum service temperature Stiffness and strength Electric conductivity While the plastic material has an increased e Mechanical damping e Heat expansion e Elongation and toughness hermoplas
18. all electric machines which are significantly and opening movements required arm muscles quieter than the hydraulic ones Photo Engel to operate the levers Properties Injection molding is a completely automated process that often produces finished components in one go In addition The components can be very complex in shape without any need for post operations It has a very high production rate in extreme cases with thin walled packaging a cycle time of only 3 to 4 seconds It can manufacture everything from millimeter size precision parts e g gears in watches to large body parts for trucks with lengths over 2 m It can fabricate really thin walls of just a few tenths of a millimeter or thicker up to 20 mm Several different plastic materials can be combined by co injection in the same shot e g a soft grip on a rigid handle Metal parts can be overmolded Figure 196 Components with so called Class A surfaces Figure 197 can be produced suitable to paint or chrome plate as often seen on cars Automated post processing operations can easily be made such as removing gates and runners assembling e g welding or surface coating the components Runners or rejected components can be directly recycled at the injection molding machine 13 Chapter 13 Post molding Operations Surface Treatment of Moldings Generally you get completely finished parts when performing injection moldings Parts
19. als calculation Click here Click here Click here Version 16 01 14 Fig 313 The start menu once the Excel file has been opened There are three different functions to choose between 1 Read about the functions of this software 2 Compare the costs between two different materials 3 Make a full part cost calculation Before you click on the key 1 accept the conditions you are only able to Read about the functions of the software The two other keys will only display blank pages The file is active Select one of the buttons below accept the conditions Fig 314 Once you have clicked on I accept the conditions you will see The file is active as shown above and all the different functions can now be used 111 Chapter 20 Alternative Processing Methods for Thermoplastics Blow Molding Blow molding is a fully automated process that produces hollow products from thermoplastic There are two main variants The first involves extrusion of a hollow tube known as a parison into a cavity between two mold halves see the figure below In the second an injection molded preform is heated and blown into the cavity see the figure at the bottom of the page Most PET soft drink bottles are produced in this way Fig 322 Blow molding with parison Picture 0 shows the extruded tube coming through the extruder head into the cavity In picture the mold has been moved to the next station where t
20. are Many of these problems are only discovered when the parts are mechanically tested or when the parts break under normal stress loads Below are some common problems due to Too weak mold plates Incorrect sprue nozzle design Incorrect runner design Incorrectly designed located or missing cold slug pocket Incorrect gate design Incorrect venting Incorrect mold temperature management Too Weak Mold Plates If you get a flash around the sprue or runners during the injection phase it may indicate too high injection speed too low lock pressure on the machine or too weak mold plates Fig 252 In the picture to the left a fan shroud in acetal is shown The gate is in the middle and it is clear that the PA i Sa mold plate has become deformed so that a flash TE around the gate has been formed even though the Toe cavity is not completely filled Moving the mold to MEN a larger machine with higher clamping force did not help in this case In the case above the first attempt to solve the problem was choosing an acetal grade with a lower viscosity However this did not solve the problem entirely see the figure below to the left Another option to solve the problem would have been to increase the wall thickness of the shroud or change the grid thickness in the round hole Neither of these solutions were chosen instead a solution using flow directors was used The wall thickness was increased by using a honeycomb pattern as shown on
21. bottle weighs 784 g when full and 430 g empty including the lid i e 55 of the product weight is in the packaging By comparison a 500 ml bottle in PET is 554 g when full and just 24 g when empty incl lid i e only 4 of the weight is packaging Plastic also has many uses in climate friendly energy production For example the wings of wind turbines are made of vinyl ester with internal PVC foam pipes in solar collectors are made from polyphenylsulfone and the casings for fuel cells are manufactured out of polyetherimide 47 Chapter 8 Modification of Polymers This chapter describes the polymerization of thermoplastics and how to control their properties by using various additives Polymerization Fig 123 95 of all the plastics produced are based on natural gas and oil The remaining 5 comes from renewable sources i e plants In 2010 plastics accounted for about 4 of the total oil consumption as follows e Heating 35 e Transport 29 e Energy 22 e Plastic materials 4 e Rubber materials 2 e Chemicals and medicine 1 e Other 1 Yo The polymerization of monomers obtained by cracking of oil or natural gas creates polymers synthetic materials that can be either plastic or rubber The type of monomer determines which type of material you get while the polymerization process itself can create different variations of the molecular chains such as linear or branched as shown below Linear polymer i e
22. cessary during the filling process Controlled cooling of the plastic melt in order to obtain correct structure of the material Warp free ejection of the part B Runner Systems Cold Runners The cold slug pocket system can be divided into different I neon parts M o yup F 1 The sprue PE 2 The runners YW 3 The gate 20 The sprue shown on the right is the connection between the cylinder nozzle and the runners of the mold In most cases it has a conical shape in order to avoid sticking in the mold when it has been packed The sprue should be easy to pull out from the fixed half when the mold is opened at the end of the injection molding cycle For some semi crystalline materials such as acetal the sprue can be cylindrical in Fig 235 Above is the runner shape The dimensions of the nozzle should be adjusted with system is the sprue is the a diameter of about 1 mm less than the smallest diameter of runner and shows the location the sprue of the gate 8 Chapter 16 Mold Design and Product Quality In Chapter 11 problems that may occur on injection molded parts due to defects in the plastic raw material are described In this chapter we will look at problems due either to badly designed molds or improper part design In Chapter 28 we will describe process related problems Mold Related Problems These types of problems are not always as easy to detect by visual inspection as material or process related problems
23. cessary to have a large internal memory as well as a fast processor 97 Chapter 18 Rapid Prototyping and Additive Manufacturing In the previous chapter we described various prototyping tools In this chapter we will look at methods to produce prototypes or small production series without use of molds made of metal Prototypes The reason for using a prototype or model during the development process of a new product is that it Shortens the development time so that the marketing process can start earlier Often facilitates communication between parties during the development process Enables opportunity to test various functions and or interactions with other components Emotionally and physically can t be fully replaced by virtual models Fig 281 Before computers were used in the development process of new products proto types and models were handmade The picture to the left was taken at the Naval Museum in Kariskrona Sweden Here two admirals in the navy in 1779 make the decision to build a new battleship using a very detailed wooden model Producing models is something that humans have done throughout history Most kids today get their first contact with models by playing with Lego or modeling clay The advanced computerized technology of 3D manufacturing used today was developed in the late 1980s and has taken steps through CAD CAE CAM CNC Which technique you choose depends entirely on the complexity of the part If
24. cument called Injection moulding process analysis There is an Excel file that can be downloaded at www brucon se On this sheet we can record most of the parameters that need to be documented to describe the injection molding process for a molded part This document was designed by the author of this book when he was responsible for the technical service at one of the leading plastic suppliers in the Nordic region You may think Why should I spend time to fill it in when I can get all the parameters printed out directly from the computer system in my molding machine The answer is that you would probably drown in all the figures and only with difficulty find the cause of the problem You would also have difficulties in finding the key parameters as the printouts from different machines are completely different oO oO 2 oO c i g gt 2 5 c y 3 Q 3 3 2 5 5 5 a wu gt e as gt off noz ue p Drying p C ea Naa Fig 456 The working tool Injection moulding This document is perfect for use both in process analysis which is described in this problem solving and as a basis for process and chapter cost optimization as well as for documenting a test drive or a start up of a new job If you fill in the document when the process is at its best you will have good benchmarks for comparison when there is a disturbance in the process Therefore we will closely exa
25. d silicon Si plastics typically consist of another five elements nitrogen N fluorine F phosphorus P sulfur S and chlorine Cl Chapter 2 Commodities Polyethylene PE Polyethylene or polyethene is a semi crystalline commodity denoted as PE It is the most common plastic and more than 60 million tons are manufactured each year worldwide Low density polyethylene LDPE was launched on the market by the British chemicals group ICI in 1939 Chemical facts Polyethylene has a very simple structure and consists only of carbon and hydrogen It belongs toa class of plastics called olefins These are characterized by their monomers having a double bond and they are very reactive The chemical symbol for ethylene the monomer in PE is CoH or CH2 CHa where the sign symbolizes the double bond Polyethylene can be graphically described as HWW HHH oie ae a a dk a H H H HI H H Fig 13 One reason that PE has become the main commodity is its extensive usage as a packaging material Plastic bags are made of LDPE Classification Polyethylene can be classified into different groups depending on its density and the lateral branches on the polymer chains UHMWPE Ultrahigh molecular weight HDPE High density e MDPE Medium density LLDPE Linear low density LDPE Low density PEX Cross linked Fig 14 When polymerizing ethylene to polyethylene the
26. de the final check of both the language and the factual content Karlskrona Sweden Ulf Bruder Chapter 1 Polymers and Plastics Sometimes you get the guestion What is the difference between polymer and plastic The answer is simple there is no difference it s the same thing The word polymer comes from the Greek poly which means many and more or meros which means unity The online encyclopedia Wikipedia www wikipedia org states the following Polymers are chemical compounds that consist of very long chains composed of small repeating units monomers Polymer chains are different from other chain molecules in organic chemistry because they are much longer than for example chains of alcohols or organic acids The reaction that occurs when the monomers become a polymer is called polymerization Polymers in the form of engineering materials are known in daily speech as plastics By plastic we mean that the engineering material is based on polymers generally with various additives to give the material the desired properties such as colors or softeners Polymeric materials are usually divided into rubber materials elastomers thermosets and thermoplastics tata NA a Fig 1 Polymers are large macromolecules where monomer molecules bind to each other in long chains There may be several thousand monomer molecules in a single polymer chain Most polymers are synthetically produced but there are also natural poly
27. e Side branched polymer Crosslinked polymer Fig 124 Polymerization of ethylene can produce different variants of polyethylene LLDPE is made up of linear chains like the one at the top of the figure LDPE has a branched chain structure as shown in the middle And PEX has cross linked chains i e where there are molecular bonds between the chains as shown at the bottom If a polymer is made up of a single monomer it is called a homopolymer If there are more monomers in the chain it is called a copolymer Acetal and polypropylene are resins that can occur in both these variations The copolymer group the second monomer is mainly located after the main monomer in the chain In the case of acetal there are about 40 main monomers between every copolymer group The copolymer may also occur as a side branch in the main chain in which case it is Known as a graft copolymer ee ee Copolymer a ia Oa Graft copolymer TT Alloy or blend Fig 125 At the top we can see the linear chain of a pure polymer such as polypropylene By adding ethylene you get a polypropylene copolymer with a block structure according to the second chain from the top This material has much better impact resistance than normal polypropylene By adding EPDM rubber monomer you get a graft polymer with a chain structure and a material with extremely high impact strength You can also create a copolymer by mixing the granules from different p
28. e defects Surface gloss Syndiotactic Tampon printing Temperature profile Tensile Tensile modulus Test methods Thermal properties Thermoplastic Thermoset Three plate mold Tolerances TPC ET TPE TPE A TPE E TPE O TPE S TPE U TPE V TPO TPS TPU TPV Trouble classification Two plate mold Two component molding U UL service temperature Ultrasonic welding Unmelts UV resistance V V rating Vacuum forming Venting Venting barrel Vibration welding Viscosity Visual inspection Voids 62 160 172 54 W Wall thickness Warpage Water injection molding Water stain Weight curve Weld lines Wrong dimension X XR chart diagram 153 211 206 176 203 210 216 221
29. ejects below 0 5 at high utilization of their machines We can no longer accept the previous hysterical troubleshooting methods where changes in the process parameters sometimes several at the same time immediately were made without any detailed analysis of the problem as soon as there was an unacceptable deviation from the specifications To meet the increasing and intense competition you have to work with both statistical problem solving methods and process control In this chapter we will describe some of these ATS Analytical troubleshooting DOE Design of experiments FMEA Failure mode effect analysis In the next chapter we will describe a large number of errors that can occur during injection molding of thermoplastics and how to solve them Analytical Troubleshooting ATS The word problem is often used with different meanings such as production problems decisions and plans to be implemented This diversity can create a lot of confusion when it comes to communication with others Working on problems in a systematic and organized way within the area of analytical troubleshooting ATS requires very specific definitions of the word problem This leads to an improvement in communication and understanding among the parties involved Definition of the Problem A problem always consists of a cause and an undesirable deviation Below is an example of this Fig 508 The cause of these black specks is usually the u
30. en ba NA uan ea BAN Aa 4 l P lymers and ad oho Se me ma sb 5 Ze MOM OS a E E sare E E E EE 9 3 Engineering Polymers en ia BA An aU 19 4 Thermoplastic Elastomers aa 21 5 High Performance Polymers eisiseed eeceecewtecnacawtaassaavdieieadvevacerrserchuissetsseeyiedudensdutveersieiderses 33 6 Bioplastics and Biocomposites ssiinuecisccssawnrseesdacssacnnansaecsnedsanahinandechuarsawantuanseesuanrsaenmeneaeclys 41 fe Plastic and the EN Iron ME nian an EN SEN NO Ian ea BRK ia 47 8 Modification OT Polymers rcciscacsscniienantemmanunaneuentessubiseshle mentanl padat mean emak aab aeueuselasusmanteeant 51 9 Material Data and Measurements ocoWoo oo Wo oom 59 10 Material Databases on the Internet oo oo oo om oom oom 65 11 Test Methods for Plastic Raw Materials and MOIINGS c cccceceseeceeeeeeeeeeeeeeaeeees 67 12 Injection Molding INCU Se SA En KAB asa 13 13 Post molding Opera ON Na isat 11 14 Different Types of MoldS oW WoWoWo Wo Wan 81 15 Structure of Molds ssepe boost bsa ale cen olmeadins situate eh aE E AEn oh BO aa ah ORN ARNAS 87 16 Mold Design and Product Oli ee SS 93 17 Prototype Molds and Mold Filling Analysis oo oo 97 18 Rapid Prototyping and Additive Manufacturing cccccccceccsecceeeeeeeeeeseeeeeeeeeeeeseees 103 19 Cost Calculations for Molding S Komo oa a NAN e EEEa anisa 111 20 Alternative Processing Methods for Thermoplastics
31. ery It is in other words not very likely that you at all under random sampling will find some details at the periphery It is not enough that the details that you happen to measure fall within the tolerance range To see the Gaussian dispersion many details need to be Fig 560 Normal distribution and mean measured and it may be time consuming But there is value a shortcut by using the standard deviation ene a Tatt LLL fae Mean value III eko PTET oo h 3 215 Chapter 30 Internet Links and Index Internet Links The following companies have contributed with information and or photos for this book and are highly recommended if you need more information about their products or services Company Acron Formservice AB Ad Manus Materialteknik AB AD Plast AB Arkema Arla Plast AB Arta Plast AB Bergo Flooring AB Clariant Sverige AB Digital Mechanics AB Distrupol Nordic AB DuPont Engineering Polymers DSM DST Control AB Elasto Sweden AB Engel Sverige AB Erteco Rubber amp Plastics AB European Bioplastics Ferbe Tools AB Flexlink AB Hammarplast Consumer AB Hordagruppen AB IMCD Sweden AB Injection Mold M Krockel IKEM K D Feddersen Norden AB Makeni AB Mape Plastic AB Mettler Toledo AB Miljosack AB Nordic Polymers Sverige AB Novamont S p A Plastinject AB Polykemi AB Polymerfront AB Polyplank AB Protech AB Re8 Bioplastic AB Resinex Nordic AB Rotationsplast AB Sematron
32. events failure of the products because actions are taken at the right time e Reduces the need for final inspection i e deliveries with high capability see terms below don t need a final inspection e Promotes customer relations because capability allows the customer to take the goods without performing an incoming inspection e Detects machine failure at an early stage and thus becomes an aid in state based maintenance e Reduces inventory costs by error free deliveries and allows a reduced inventory e Can reduce stress in production as the need to measure and control the process is reduced e Can facilitate price discussions as accurate deliveries usually mean more satisfied customers e May increase staff engagement through increased understanding of the process as it is easier to see patterns and trends in the process e Provides a uniform approach when there is no room for sole and absolute discretion e Is atool in the Lean process that provides continuous improvement with focus on satisfying the customer Definitions in SPC Normal Distribution Gaussian Dispersion This is the way in which the measured values in most cases will be distributed as a result of the random S ooo bah og spread around its mean value highest point of the FHE hump see the figure to the right 22222229 Notice that most of the measured values are around Rare HEERE the hump and that there are fewer values closer to the values BEE periph
33. f multiple functions in the same component e Different assembly methods e Surface treatments 3 Environmental requirements e Chemical restrictions e Recycling easy to disassemble and to sort 4 Manufacturing requirements e Processing methods e g injection molding e Molding equipment 127 Chapter 22 Reguirements and Specification for Plastic Products The reguirement specification will differ from product to product depending on what it will be used for For a spatula heat resistance and food approval are key requirements for the blade to an indoor hockey stick toughness and the ability to shape the blade afterward are the most important properties This section will address most of the properties that should be included in the requirement specifications of thermoplastic products It is important to bear in mind that the tougher the reguirements for a product the more expensive it becomes to manufacture Below there is a list of the different things that need to be considered when drawing up the requirement specification for a new plastic product 1 Background information 9 Electrical properties 2 Batch size 10 Environmental impact 3 Part size 11 Color 4 Tolerance requirements 12 Surface properties 5 Part design 13 Other properties 6 Assembly requirements 14 Regulatory requirements 7 Mechanical load 15 Recycling 8 Chemical resistance 16 Costs 1 Background Information This generally refers to
34. gth Elongation am Impact strength Delrin Maximum service temperature one Flame resistant classification Electrical properties Rheology flow properties Shrinkage Density Product Information PRELIMINARY DATA Delrin S1IIDF NOOO Delia 3 DF is Ai eer li oer acetal amii Gh lee oya Ti fer econ rocildeeg IE haa onpeoed Herma sabah sore aoine properti giie jent dieman ababaka liom Tensile Strength and Stiffness Stiffness tensile strength and toughness in terms of elongation can be obtained by the curves in tensile testing of test bars Shot with Den Peat Engineering Polen www dopon com eee es pene Fig 149 In a preliminary data sheet only a few data are shown compared with the data sheets that occur in so called standard grades or in the CAMPUS material database In the data sheet above which describes an acetal from DuPont 16 different data items divided into the following groups are shown Fig 148 The picture shows a test bar in a tensile tester All plastic producers measure the mechanical properties on specimens manufactured according to various ISO standards which makes it possible to compare data between different manufacturers Photo DuPont e Mechanical e Thermal e Other density and mold shrinkage e Processing Source DuPont 59 Chapter 10 Material Databases on the Internet A good way to find information about different plastic materials is to visit the raw material p
35. gth and impact strength Increased service temperature Reduced influence of ambient temperature and humidity on the mechanical properties Less tendency to creep under load Improved chemical resistance especially considering the fluids used in cars i e fuel oil antifreeze detergents Improved flame retardant properties Improved electrical insulation properties Less friction and wear Improved barrier properties primarily to fuel and oxygen In addition any new material would be required to Have a reasonable price in relation to the properties it offers Be easy to process using conventional machinery Be simple to recycle Advanced reinforcement systems with carbon and aramid fibers or coating with so called nano metals can also be used in combination with advanced polymers to achieve the above goals Plastics designed to replace metals are sometimes called structural materials and clearly have a great role to play in the future especially since to date it is estimated that only 4 of the potential applications have been converted This section gives an overview of the following semi crystalline advanced polymers 1 Fluoropolymer PTFE 2 High performance aromatic polyamide PPA 3 Liquid crystal polymer LCP 4 Polyphenylene sulfide PPS 5 Polyether ether ketone PEEK And the following amorphous polymers 6 Polyetherimide PEI 7 Polysulfone PSU 8 Polyphenylsulfone PPSU Recycling
36. he tube is blown out toward the walls of the cavity using compressed air In picture the tube has been completely pressed out against the cavity walls and allowed to cool Picture shows the finished part being ejected from the mold As a rule only special grades with relatively high viscosity are used for blow molding e g PE PP PVC PET PA and some thermoplastic elastomers Multiple extruders can be used for different layers of the parison for example to improve the barrier properties of a product The hose can also be extruded in sequence e g soft segments alternating with rigid ones to produce rigid tubes with integrated soft bellows 117 Chapter 21 Material Selection Process A major task of designers and project engineers is selecting the right material for their applications When the materials under consideration include plastics this task is particularly difficult since there are hundreds of different polymers and thousands of different plastic gualities to choose from Finding the right material reguires knowledge experience your own or access to that of others and sometimes a little luck If you choose a material that is considered somewhat too good this will usually be reflected in the cost being seen as somewhat too high which can have an effect on your competitiveness However on the other hand if you choose a material of a borderline quality you run the risk of complaints and a bad reputati
37. it is a part with simple geometry it is usually cheaper to produce it using cutting methods such as milling laser or water cutting If the part is more complex rapid prototyping additive technology may be the only possible solution or a much cheaper solution compared to cutting techniques even if the material is significantly more expensive about 50 SEK kg of plates in polyamide and 3000 SEK kg for photopolymer in the SLA method However you must take into account that the production of milled models requires removal of up to 90 of the material while the amount of material waste when using rapid prototyping is negligible Rapid Prototyping RP This kind of additive technology is fairly new and goes under a variety of names When performing a search the following terms may be helpful rapid prototyping RP rapid tooling RT rapid application development RAD additive manufacturing AM or 3D printing We will take a look at the following methods SLA Stereolithography SLS Selective Laser Sintering FDM Fused Deposition Modeling 3DP Three Dimensional Printing Pjet PolyJet oe SY 103 Chapter 19 Cost Calculations for Moldings Most molders are using advanced computer based software to calculate costs or post costs of injection molded parts Unfortunately it is very seldom that injection machine setters have insight into or get the opportunity to use such software even though they have great potentia
38. l to affect the costs by adjusting the injection molding parameters How often does it happen that setters add a few seconds of extra cooling time when they have a temporary disturbance of the injection molding cycle And then forget to change back to the original settings before the parameters are saved for the next time the mold will be set up Those extra seconds can mean thousands of Euros in unnecessary production costs per year and may also reduce the company s competitiveness The purpose of this chapter is to show how a fairly detailed cost calculation for injection molded parts can be made The setter also gets a tool that enables him her to see how changes that are made in the process can influence the cost of the molded part This tool is based on Microsoft Excel and is available for downloading at www brucon se The user does not need any extensive knowledge of Excel in order to fill in the input values required to immediately obtain the final cost picture at the bottom of the page The rest of this chapter will explain how to use the Excel file and what the different input values mean When you open the file called Costcalculator xls you must first make a copy of this file to your computer s hard drive otherwise the macro functions won t work Depending on how the default values are set for your own Excel program it may be necessary to make modifications of the security settings Detailed information of how this is to be done can als
39. manding applications in the automotive domestic appliances sports industrial engineering electronics and consumer goods industries Fig 167 The CAMPUS window consists of four smaller windows The top left is the list of all the materials The top right is the properties window which in this case shows the mechanical properties of the selected grade Delrin 100 by DuPont The bottom left is the information window with the information about Delrin 100 and to the right we can see the different curves for this material in the graphics window Properties of CAMPUS 5 2 The database is free to download You can get the material process from the Internet data in curve overlay and polar You can sort the properties in tables charts You can compare different materials in You can get the material s flow a tabular form properties to be used in mold flow You can compare different materials Panos graphically You can only compare materials from one specified material producer at You can get chemical resistance for the aim materials The database must be updated vou can specify and print your own data manually sheet You can search for materials meeting various criteria on properties 65 Chapter 11 Test Methods for Plastic Raw Materials and Moldings In this chapter we will describe the plastic raw material producer s guality control data the various material defects that a molder may find as well as the test
40. mers such as natural rubber and amber that have been used by mankind for thousands of years Other natural polymers include proteins nucleic acids and DNA Cellulose which is the major component in wood and paper is also a natural polymer Fig 2 Amber is a natural polymer The mosguito in this stone got stuck in the resin of a conifer more than 50 million years ago something to think about when considering the decomposition In other words plastic is a synthetically manufactured material composed of monomer molecules that bind to each other in long chains If the polymer chain is made up solely of one monomer it is called polymer homopolymer of certain polymers in nature If there are several kinds of monomers in the chain the polymer is called copolymer An example of a plastic that can occur both as homopolymer and copolymer is acetal Acetal is labeled POM polyoxymethylene and is mostly up built of a monomer known as formaldehyde The building blocks atoms in formaldehyde are composed of carbon hydrogen and oxygen Most plastic materials are composed of organic monomers but may in some cases also be composed of inorganic acids One example of an inorganic polymer is a silicone resin consisting of polysiloxanes where the chain is built up of silicon and oxygen atoms Carbon and hydrogen are the other dominant elements in plastics In addition to the aforementioned elements carbon C hydrogen H oxygen O an
41. methods you can use when you want to analyze these kinds of defects Ouality Control during Raw Material Production The plastic producers measure the quality of their plastic raw material at regular intervals random sampling Depending on the type of polymer and the included additives they use different test methods during production In general they are testing e Viscosity which is dependent on the molecular chain length e Fiber content i e the ash content after complete combustion of the polymer e Moisture content of each batch at the packing station Glass fiber content Fig 171 Here we can see the test results of 12 different batches of a 30 glass fiber reinforced grade The aim is to be as close as possible to 32 30 30 but as long as the result is within the green si i lines 30 t 2 the material is approved for 28 S delivery Batches 7 and 11 are not acceptable Batch number and must be redone in order to fall within the 1 2 3 4 5 6 7 8 9 10 11 12 delivery limits Test method unit iso Specified A Moisture content 15512 0 20 A Ash content 3481 31 35 z manng portre ee PP Fig 172 In the table to the left we can see that B Density g cm3 4183 134 141 thermal and mechanical properties are tested at B Tensile strength MPa 527 2157 least once a year 5 Songation 4 Ee These values are then used for the published B Stiffness E modulus MPa 627 28000
42. mine the structure of this document and explain the meaning of the information in each input field On the last page of this chapter is the document in full page format Contact Information In the top part of the page there are some fields that can be filled in If you only plan to use the page for internal documentation it will probably be redundant to fill in these data However you should always fill in the date and contact person If after several years you need to go back and see how a particular setting was made it is usually interesting to know who did it and then get additional information It is also important to know when the setting was made if several settings have been made over time If you use the document to communicate externally with a raw material supplier or a sister company etc it also facilitates this if the contact details are filled out s1 Please use the tab button when filling in this sheet a e i Fig 457 Contact information 165 Chapter 26 Injection Molding Process Parameters In this chapter we will publish the main injection molding parameters for a number of thermoplastics When setting an injection molding machine with a new resin you should always use the recommended process data from the raw material producer if available If you don t have them look on the producer s website or search for them on the Internet NOTE The values shown in the tables in Figure 506 are typical for an
43. mold B Runner systems cold runners 1 LG YW 1 Lf m C Runner systems hot runner een a D Cold slug pockets pullers 1 p 9 7 7 WLLL N N a M H aa lo NG N Kg NO E Tempering and cooling systems F Venting systems G Ejector systems H Draft angles J H G 7 Ja N NW EA Z2 A N A Pa PPP 4 4 co ya 1 ae NK 20 Z l f Fig 234 To the right is a schematic diagram of the structure of a two plate mold N E i SS Yum NI sbi 1yemwuwm 3 281 WY 77 ZA O shows the nozzle centering of the tool O shows the sprue and the channel between the nozzle of the cylinder and the runner shows the runner that leads the material through the gate into the cavities shows the gate that leads the material into the cavity shows the cavity is the cold slug pocket is the cooling system O shows the ejector system shows the venting and shows that the part has a draft angle e amo ami SS N AL oo A W N r Sf GFF A a r AY Bs Z OM WO OOO wy WY 3171 X Ns WMA a 4 a ee J 7 7 ae SS N N A The Function of the Mold There are many demands on a mold in order to obtain high guality products The dimensions have to be correct Filling of the cavities has to be shear free Good venting is ne
44. mplex or when the production mold is very expensive Within the automotive industry these kinds of molds sometimes are named soft molds as they often are made in aluminum or in soft steel When it comes to more simple part or mold design most prototypes have been replaced by a mold filling analysis i TA an 4 h P Fig 263 Above is a prototype mold highlighted in red in aluminum for the cams shown in the figure to the right Here only one part is made in each shot Below is the production mold in steel with 16 cavities This mold is about 30 times more expensive to produce compared to the prototype mold in aluminum Mold Filling Analysis Fig 264 Here we can see a common component used in assembly of furniture AD Plast in Sweden developed this component in PPA with glass They won the prestigious price Plastovationer 2009 by successfully replacing metal with plastic The cam is stronger than the former zinc one without needing to change the outer dimensions Source AD Plast AB Mold filling analysis is a computer based tool that facilitates the ability to get accurate plastic parts in less time when producing a new part or modifying an existing mold Fig 265 On the image you can see a mold designer in front of his PC working with Moldflow a mold filling software Such software is able to run on standard PCs but requires a lot of computing power In order for the calculations to run as fast as possible it is ne
45. n training Plastic and machine distributor Injection moldings Plastic distributor Eguipment for analysis Climate smart plastic bags Plastic distributor Bioplastics Injection moldings Plastic raw material Plastic distributor Recycled products Rapid prototyping eguipment Bioplastics Plastic distributor Rotational moldings Vacuum forming Injection moldings Injection moldings and extrusion Plastic raw material Injection moldings Laser marking eguipment Plastic clips 223 Index A ABS Acetal Action planning Actual value Additives Advanced thermoplastics AFS Air bubbles Air streaks Amorphous Analytical troubleshooting Anisotropy Aromatic polyamide Assembly methods Atactic B Back pressure Biocomposites Biodegradable Bioplastic Biopolyamides Biopolyester Biopolymers Black specs Blisters Blow molding Brittleness Burns C Cable production CAMPUS Capability Cause verification Cellulose Charpy Chemical properties Chrome plating Cold slug Cold slug pocket Color streaks Compostable plastics Conical gate Control chart Control limit Cooling Cooling time Copolymer Corner radius Cracks Crazing 224 Creep Crystalline Cushion Cycle time D Degradable Delamination Design rules Deviation chart Diesel effect Discoloration Dosing Dosing time Draft angle Dry air dryer Drying DuraPulp E Ejection Ejection problems Ejector pin marks Electrical properties
46. ng but would like to highlight some of them in company order Kenny Johansson Acron Formservice AB Anders Sj gren AD Manus Materialteknik AB Michael Jonsson AD Plast AB Johan Orrenius Arla Plast AB Kristian Ostlund Arta Plast AB Eric Anderzon Bergo Flooring AB Anders Sjoberg Digital Mechanics AB Kristina Ekberg Elasto Sweden AB Frans van Lokhorst Engel Sverige AB Carl Dan Friberg Erteco Rubber amp Plastics AB Bim Brandell Ferbe Tools AB Niclas Forsstr m Fristad Plast AB Mattias Ryden Hordagruppen AB Lena Lundberg IKEM Magnus Lundh K D Feddersen AB Heidi Andersen and Lars Klees Klees Consulting Prof Carl Michael Johannesson KTH Prof Robert Bjarnemo LTH Oliver Schmidt Materialbiblioteket Joacim Ejeson Nordic Polymers AB Michael Nielsen Nielsen Consulting Marcus Johansson Plastinject AB Patrik Axrup Polykemi AB Edvald Ottosson Protech AB Thomas Brack Re8 Bioplastic Thomas Andersson Resinex Nordic AB Martin Hammarberg Sematron AB Joachim Henningsson Spring Slope Nils Stenberg Stebro Plast AB Ronny Corneliusson and Tommy Isaksson Talent Plastics AB and Jan Olof Wilhemsson Tojos Plast AB The Internet links to these companies and to some other companies who have also contributed information and images can be found on page 223 in the book Finally want to say a very big thanks to Vicki Derbyshire and Desiree von Tell who helped translate this book and to my friend Stewart Daykin who ma
47. njection Multi component mold N Nonlinear Normal distribution Notch sensitive Nozzle Nylon O Oil stains Orange peel P PA Painting Part cost calculation PBT PC PE PEEK Peripheral speed PET PEX PHA Physical properties Pigment orientation PLA Plastic PMMA Polyamide Polycarbonate Polyester Poly ether ketone PEEK Polyethylene Polymer Polymerization Polymethyl acrylate Polyphenyl Polypropylene Polystyrene Polysulfone Polyvinyl POM Post mold shrinkage 146 215 154 169 19 206 204 225 PP PPA PPC PPSU Printing Problem analysis Process capability Prototype molds PSU PTFE PTT PVC Pyrometer Q Quality control R Record grooves Recycling Regranulate Regrind Reject Relaxation Replacement cost calculation Requirements Ribs Riveting Rotation welding Rotational cores Rotational molding Runner S SBS Screen printing Screw diameter Screw speed SEBS Semi crystalline Service temperature Setpoint SFP Shut off nozzle Silver streaks Sink marks Six Sigma SPC Specific heat Specific volume Splays Splays Sprue Stack mold Standard deviation Starch 226 204 166 166 112 147 116 127 155 164 161 125 87 28 179 179 28 62 186 191 167 199 197 216 215 199 200 213 216 43 Stiffness Strain curves Stress strain curves Stress concentration factor Stringing Styrofoam Suck back Surface coating Surfac
48. ntent for the material provided that the dry air dryer is working with a sufficiently low dew point Note also that if you dry the material longer than the indicated time in the table you should reduce the temperature 10 20 C because some materials can oxidize or degrade thermally Material where Needs normally not to be dried is recommended in the table may still need to be dried if condensation will occur on the surface of the granules If this is the case a drying temperature of 80 C and a drying time of 1 2 hours usually works well The reason that the maximum Peripheral speed is published in the tables is that many molders in good faith are dosing up the next shot with too high of a screw speed and thus unnecessarily degrading the polymer chains in the cylinder by high shear and friction resulting in poorer quality On page 179 in Chapter 25 you will find a formula where you can calculate the maximum allowed peripheral speed to maximum allowed rotation speed depending on the screw diameter If you cannot find the recommended maximum peripheral speed for your resin you should take into account that high viscosity grades sometimes require 30 lower rotation speed compared to a less viscous standard grade For example impact modified acetal with a melt index of 1 2 g 10 min has a recommended maximum peripheral speed of 0 2 m s compared to 0 3 m s for a standard grade with melt index of 5 10 g 10 min For glass fiber reinforced grades
49. o be found on the author s homepage The Excel file is also in read only mode so it should be saved under a different name once you have completed it Cont Cahite 0 ead Ordy Compatitbiity Mode Mic rocott baret Normal Part Tusersido Tusemibite Normal jet Delete t a Cost calculator This database the data and reports generated by the software have been provided pursuant to the following agreement containing restrictions of their use They are also protected by copyright law and cannot be copied distributed transmitted transcribed or translated into any human or computer language in any form or by any means to any third parties without the expressed consent of Bruder Consulting AB Kariskrona Sweden Bruder Consulting AB disclaims all warranties with regard to this software including all implied warranties of merchantability and fitness In no event shall Bruder Consulting AB be liable for any special indirect or consequential damages or any damages whatsoever resulting from loss of use data or profits whether in any action of contract negligence or other tortious action arising out of or in connection with the use or performance of this software Please activate the file by accepting the conditions above Click here accept the conditions Read about the functions of the software To compare costs between two To make a full part cost Limitations in beta version Licence conditions etc different materi
50. obased Nonbiodegradable Biodegradable Conventional plastics e g PE PP PVC PS ABS PET PUR Petroleum based Fig 96 The illustration shows how to divide thermoplastics into conventional petroleum based plastics and different types of bioplastics 41 Chapter 7 Plastic and the Environment At first glance the title of this chapter may seem ambiguous Do we mean how plastic affects our environment Or how various environmental factors affect plastic We will consider both aspects The use of plastics is constantly increasing One important reason is the fact that plastics contribute to increased resource management for example saving energy and reducing emissions Plastics also contribute to technological development The plastic industry wants to contribute to a sustainable society That s why they invest considerable resources Fig 111 The use of plastics reduces in the production of environmentally friendly materials our climate impact by saving energy and resource efficient processes and reducing CO2 emissions Plastic is Climate Friendly and Saves Energy That plastic can slow climate change by saving energy and reducing our emission of greenhouse gases is not something we may instantly think of The recent study Plastics Contribution to Climate Protection concluded that the use of plastic in the 27 EU member states plus Norway and Switzerland contributes to the following environmental benefits
51. olymers In this case the material is known as an alloy or blend ABS PC is an example of this type of copolymer 51 Chapter 9 Material Data and Measurements In this chapter we will go through those properties of thermoplastics that are often reguested by designers and product developers when they are looking for a material in a new product or when they must meet different industry or regulatory reguirements such as electrical or fire classification When plastic producers develop a new plastic grade they usually also publish a data sheet of material properties Sometimes this is made as a preliminary data sheet with only a few properties If then the product will be a standard grade a more complete data sheet will be published Many suppliers publish their material grades in the CAMPUS or Prospector materials databases on the Internet which can be used to some extent free of charge see next chapter CAMPUS is very comprehensive and can describe a Fig 147 What are the different reguirements from authorities on a material with over 60 different data types and at the same so unremarkable product as an time you can get graphs e g stress strain curves and electrical outlet that must be chemical resistance to many chemicals fulfilled to be sold on the market The most reguested data when it comes to thermoplastics and that are usually in the preliminary data sheet are Tensile or flexural modulus Tensile stren
52. on in the marketplace which also affects your competitiveness How Do You Select the Right Material in Your Development Project Let s take a new iron as an example Before the designer starts thinking about what materials to use in the iron he must be clear about the following e What should the new iron look like e What different functions should it have What will it cost When answering the above questions the designer should make a list of the requirement specifications as detailed as possible Fig 348 So what should this new iron J 3S look like Development Cooperation A good way to reduce development time when it comes to plastic components is to utilize the collective expertise and experience of a project team consisting of its own development department working with a potential material supplier and potential manufacturers e g molder and mold maker Material supplier Establishing the Requirement Specifications To establish a complete requirement specification from scratch is very difficult As a rule one always encounters new challenges in development work The requirements can be divided into categories 1 Market requirements New functionalities Fig 349 Successful collaboration with project subcontractors generally shortens Regulatory requirements development time significantly Competitive situation Cost objectives 2 Functionality requirements e Integration o
53. range of properties can be achieved With mixture concentrations below 20 we usually call the materials impact modified PP while levels above 60 give the more rubber like properties The recycling code for TPE O is gt PP EPDM lt Properties of TPE O Chemical facts Cost effective substitute for rubber TIS predominant Te ves are mnaceUp ar monomers of polypropylene and uncross linked t High stretch factor EPDM rubber ethylene propylene diene monomer M Good tear resistance class The properties depend on the monomer units where n can be 90 35 and m 10 65 Flexible at low temperatures Good surface finish Good chemical resistance CH on Can be UV stabilized n Easy to process Can be colored 3 Paintable primer required fron CH F CH CH Ian ont Deformation properties i e setting Cote m characteristics not as good as rubber EPDM s ES CH CH PP 2 7 Chapter 5 High Performance Polymers Advanced Thermoplastics In everyday speech we describe this type of material as high performance which means plastics with the best properties What kind of gualities do we have in mind when developing materials to belong to this category Below we can see the wish list the researchers may have had when they set out to improve the properties of engineering plastics Improved ability to replace metals Improved mechanical properties such as stiffness tensile stren
54. re are various processes resulting in more or less lateral branches on the molecular chains A smaller number of lateral branches give a higher crystallinity molecular weight and density since the chains can thus be packed more densely HDPE has few or no lateral branches and is also called linear polyethylene Properties of Polyethylene Low material price and density Excellent wear resistance UHMWPE Excellent chemical resistance Easy to color Negligible moisture absorption Stiffness and tensile strength Food approved grades are available Cannot handle temperatures above 80 C High elasticity down to lt 50 C Difficult to paint The mechanical properties depend largely on the presence of lateral branches crystallinity and density i e the type of polyethylene Chapter 3 Engineering Polymers Polyamide or Nylon Polyamide is a semi crystalline engineering plastic denoted by PA There are several different types of polyamide of which PAS and PA66 are the most common Polyamide was the first engineering polymer launched on the market It is also the largest in volume since it is widely used in the automotive industry Polyamide was invented by DuPont in the United States in 1934 and was first launched as a fiber in parachutes and women s stockings under the trade name Nylon A few years later the injection molding grades were launched Nylon became a general term DuPont lost the trademark and curren
55. re consists of both thermoplastic hard segments and elastic soft segments The crucial difference to traditional rubber is the lack of or at least very slight cross linking between the molecular chains Most of the various TPEs offer a cost effective alternative to rubber in a variety of applications thanks to its suitability for different processes such as injection molding extrusion film and blow molding Feature wise however rubber has the advantage of higher elasticity and lower compression under constant load All the thermoplastic elastomers are ideal for material recycling although incineration for energy extraction is also an option TPEs can generally be divided into the following groups TPE O olefin based elastomers TPE S styrene based elastomers TPE V olefin based elastomers with vulcanized rubber particles TPE U polyurethane based elastomers TPE E polyester based elastomers TPE A polyamide based elastomers TPE O TPE O or TPO thermoplastic elastomers where the O stands for olefin are a blend of polypropylene and EPDM uncured rubber particles Because it has a PP matrix TPO takes on a semi crystalline structure TPO based elastomers are among the largest and most cost effective TPEs available They have been on the market since 1970 and leading manufacturers are Elasto Elastron Exxon Mobile So F teR and Teknor Apex By mixing the levels of EPDM in PP at concentrations from 10 to 65 a great
56. roducer s websites or visit independent material databases on the Internet In this chapter you will find three leading global databases CAMPUS and Material Data Center from the European company M Base and the Prospector Materials Database from the U S company UL IDES The great advantage of all the databases is that you can compare the material data no matter who the producer is as all the materials in the databases are tested in exactly the same way CAMPUS About 20 large plastics raw material producers use CAMPUS to inform their customers about their products Software for CAMPUS is offered free by the producers and can be downloaded directly via the Internet www campusplastics com The database is updated regularly and can be updated via the CAMPUS website 5 2 IDuPont Engineering Polymers 2010 08 16 File Query Options Window Help e ao a RA BO oe ask ks OH S ees Oe 406 grades Polymer Material Fam Rheo Mech Therm Elec Other Mat Tst Mech FG Other FG Tst FG LI Crastin T835FRUV NC010 PBT GF5 FR 17 z MH Delrin 100 NCO1C POM E C Delrin 100AF C Delrin 100AL NC010 Tensile modulus ISO 527 1 2 Mechanical properties C Delrin 100KM NC000 Yield stress ISO 527 1 2 C Delrin 100P NC010 Yield strain C Delrin 100PE NC010 C Delrin 100ST NC010 C Delrin 100T NC010 Stress at 5096 strain ISO 527 142 ISO 527 142 Nominal strain at break ISO 527 112 C Delrin 10
57. se of too high screw speed in the injection molding machine This leads to a screw deposit on the surface of the screw that degrades thermally and causes the specks on the surface of the button Fig 507 The black specks that you can see on the red button of the safety belt lock are an unacceptable deviation It is normally defined as a surface defect 185 Chapter 28 Troubleshooting Causes and Effects Molding problems In the previous chapters we dealt with defects caused by bad material In this chapter we will discuss process related errors These can generally be divided into the following main groupS 1 Fill ratio which means unfilled or overfilled parts 2 Surface defects 3 Strength problems 4 Dimensional problems 5 Production problems In general process problems belong to several of the main groups In order to identify and classify a problem and then find possible causes for it you should ask the following guestions 1 What kind of problem is it 2 What has changed 3 When did this happen 4 Where do the error errors occur e On the part parts the same place or randomly e In the production cycle 5 How often does it occur 6 How serious is it 1 IEF Ew A p 1 a Y i F iF a E o f i O E 8 Li pe L r s d Al P1 Hiri 1 p J E E L L L d
58. te in such a way that this book can be understood by everyone regardless of prior knowledge about plastics The book has a practical approach with lots of pictures and is intended to be used both in secondary schools universities industrial training and self study In some of the chapters there are references to worksheets in Excel that can be downloaded free from my website www brucon se In addition to the above mentioned persons would like to extend a warm thanks to my wife Ingel6ov who has been very patient when I ve been totally absent in the wonderful world of plastics and then proofread the book my brother Hans Peter who has spent countless hours on adjustments of all the images etc and my son in law Stefan Bruder who has checked the contents of the book and contributed with many valuable comments would also like to thank my previous employer DuPont Performance Polymers and especially my friends and former managers Bj rn Hedlund and Stewart Daykin who encouraged the development of my career as a trainer until reached my ultimate goal and dream job of global technical training manager They have also contributed with a lot of information and many valuable images in this book also want to say a big thanks to my friends and business partners in all educational programs in recent years who have supported me and contributed with many valuable comments information and images for this book The whole list would be very lo
59. tics Thermosets TER we To oo Pa Fig 394 This table shows that thermoplastics have certain Stiffness elu 1 advantages over metals such as decreased weight corrosion Strength al waw li durability thermal and electric T t insulation freedom of design empara 38 4 and recycling potential Z lt disadvantaged in terms of Electric insulation Lal fi stiffness strength and AT sensitivity to high temperature Freedom of design e tT Thermosets follow the same patterns as thermoplastics but 1 Recycling e are much harder to recycle amp Reference equal T Better Worse 145 Chapter 24 Assembly Methods for Thermoplastics Most designers seek to make their plastic products as simple as possible while at the same time integrating all the necessary functions The product should preferably come out of the mold complete and ready but sometimes for functionality or cost purposes it can be necessary to make the product in two or more parts that are assembled at a later stage There are several assembly methods for thermoplastic products and this chapter considers most of them To begin with it is common to divide the assembly methods into those where the product can be disassembled and reassembled several times e g using screw joints and those permanent methods whereby components are assembled only once e g welding Fig 432 and 433 This bobbin is made as two identical halves in
60. tly markets its polyamides under the trade name Zytel Ultramid from BASF Durethan from Lanxess and Akulon from DSM are some of the other famous trade names on the market Classification The development of polyamide has focused on improving the high temperature properties and reducing water absorption This has led to a number of variants where in addition to PAS and PA66 the following types should be mentioned PA666 PA46 PA11 PA12 and PA612 About a decade ago aromatic high performance polyamides were introduced usually known as PPA which stands for polyphthalamide The latest trend is bio polyamides made from long chain monomers e g PA410 PA610 PA1010 PA10 PA11 and PA612 Chemical facts Polyamide is available in a number of variations labeled alphanumerically e g PA66 indicating the number of carbon atoms in the molecules that make up the monomer PA6 is the most common type of polyamide and has the simplest structure NH c chf PA66 has a monomer that consists of two different molecules wherein each molecule has six carbon atoms as illustrated below O O II II NH CH2 NH C CH2 C Amide group Acid group Fig 43 Polyamide has an excellent combination of good electrical properties high operating temperatures and flame retardant capability up to UL V 0 classification The material is therefore used for electrical components such as fuses circuit breakers transformer housing etc Photo
61. values in the producer s literature or in B Impact strength Charpy Mma 173 sis databases It is only in exceptional cases that B HDT 1 80 MPa D789 245 molders can get their material regularly tested A Every batch B Annually with these types of testing The test values that the producers receive during the random sampling of the various production batches will as a rule be attached together with the material or invoice in the form of a delivery certificate In this certificate you will find the same lot number also called batch number that you will find stamped on the bags or octabins It is very important to keep these certificates in case of a complaint because the production plants always want information about the batch Fig 173 To the right you can see a delivery certificate from DSM for Akulon K224 G6 natural PA6 with eee osm spines aici ade DSM Engineering Plastics B V Here they have measured g g Moisture content of 0 050 and Insp certificate 3g 4 EN 10204 Page 1 1 indicated the upper delivery limit to be 0 150 An ash content glass fiber content of 29 9 and indicated the limits of supply to be Material Our Your reference 0000019277 K224 G6 98 99 99 71104 110 2372 Brandname AKULON amp Batch 1150341606 Ouantity 22 000 KG between 28 0 and 32 0 Inspection lot 40000214809 from 07 09 2011 2 Lower Upper O A relative VISCOS ity In a Characteristic Unit Value Limt Limit
62. with the correct color are ready to be used immediately or ready to be assembled with other components However there are opportunities to further enhance improvements of the injection molded part by surface treatment Usually surface treatments are made to improve the aesthetic value but may sometimes be required to meet the functional needs Fig 211 A headlamp housing made in PBT In this picture you can see the chrome plated reflector through the glass which has been made in polycarbonate The surface treatment has been made in order to get the optic properties as well as adding protection to the surface from the high heat generating light sources The various surface treatment methods used for thermoplastics that we will cover are e Printing labeling e IMD In mold decoration e Laser marking e Painting e Chrome plating or metalizing Printing There are many different reasons for printing on plastic products You often want to add a label or add instructions onto the surface of the product The printing methods that we will describe in this chapter are e Hot stamping e Tampon printing e Screen printing Fig 212 Containers cans and bottles with labels and instructions added to the surface On many of these an adhesive label in either paper or plastic foil has been attached There are also various methods to print directly on the plastic surface 11 Chapter 14 Different Types of Molds In this chapter we
63. you will usually find the recommended maximum peripheral speed to be 30 50 of the speed for the unreinforced grade Also impact modified flame retardant grades used to be more sensitive to shear than standard grades Having sufficiently high Hold pressure is especially important for semi crystalline plastics Usually it is recommended to have as high a pressure as possible without getting flashes in the parting line or having ejection problems We publish hold pressures because many molders sometimes in good faith set far too low a hold pressure resulting in poorer quality Other important parameters such as hold pressure time hold pressure switch back pressure injection soeed and decompression are more dependent on the part design and machine conditions We therefore cannot give any general values of these parameters but refer you instead to Chapter 25 183 Chapter 27 Problem Solving and Quality Management Increased Quality Demands The accelerating developments in both processing technology and thermoplastics have led to new uses such as metal replacement electronics and medical technology At the same time the demands on plastic components have increased when it comes to performance appearance and other characteristics The slightest deviation from the requirements and specifications must immediately be addressed and thus the goal for many molders is to deliver error free products zero tolerance while keeping their own r

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