HEIDON Manual Rev0201
Contents
1. Portable Friction Meter HEIDON Tribo Gear us Tvpe 94i User s Manual Contents O A lt ImtrOQUCLI GA i A 3 Measurement Principle sas d desea ds 4 MOM PriN IP IG a aj ba ka tr eaves 5 External Viewwand Part NAMES mencuat ri i 6 Using the Portable Friction Meter nn 7 Notes Regarding Handling of the Friction 2 0 9 Characteristics and Performance nanna nanna 10 STD POCIICAT B due 11 1 Introduction The HEIDON Tribo Gear us Tvpe 94i is a portable measuring device which makes it easv for anvone to measure the static friction coefficient of objects In the past static friction was typically measured using the incline method and a strain gauge However this method posses many difficulties when used in confined spaces such as laboratories etc The HEIDON Tribo Gear us Type 94i is a new type of static friction measuring device which completely eliminates these difficulties 2 Measurement Principle Static friction is generally measured using the incline method As illustrated in Diagram 1 below when an object of weight W is placed upon a surface which is gradually inclined at an increasing angle at some angle of inclination the acceleration of2. d the current magnetic field and force move at right angles to each other This results in a force being applied to the coil assembly This force is proportional to the value of the current passing through the coil Because this is efficient a large force can be generated even with low current levels F Coil Assembly B Current B Magnetic flux density 1 F Force Magnetic Circuit Fleming s Left hand Rule VCM Cut Away Diagram Force F BIL F Force B Magnetic Flux Density T Current L Total length of coil m 5 4 External View and Part Names Display Panel 2 Average Button 3 Power Button 4 Measure Button 5 Main Unit Circuit Board 7 Slider Battery Case 9 Slider Holder 5 Using the Portable Friction Meter 1 Attacha Sample The coefficient of friction between to samples can be measured either bv attaching the samples to the slider with two sided tape or by fixing the samples in place using the O ring supplied attached to the slider 1 Affixing samples using two sided tape Use a piece of two sided tape pre cut to a size slightly smaller than the samples to affix the samples to the slider ES 1 CD 2 Affixing samples using the O ring lt gt Remove the O ring which is attached to the slider and then wrap the O ring around the samples so that they are fixed in place This method should only be used for thin samples eS The displayed coeff
3. gravity acting upon the object will exceed the static friction which tends to keep the object in place and the object will begin to slip This angle q theta is referred to as the friction angle Taking us as the coefficient of static friction the force of friction is the vertical force with which the object pushes down upon the surface Wcosq and the area us usWcosq Therefore the force with which the object tends to slip down the slope Wsinq is thus tanq In this way the coefficient of static friction can be obtained by measuring the friction angle q Diagram 1 20 Diagram 2 Wsinf usWcosd Wtand usW us Wsind Wcos us Wtan W tano Applying this principle a VCM voice coil motor is used to apply a horizontal force to an object of weight W as illus trated in Diagram 2 The object will begin to move the instant that the force thus applied exceeds the force of friction The force F generated at this time is obtained bv the formula F ki Therefore the coefficient of static friction is obtained bv the formula ki W k Constant force applied by the VCM i Current at the instant the object began to move W Weight of the object g 3 The VCM Principle The VCM voice coil motor operating principle is an application of Fleming s left hand rule As illustrated in the diagram below the VCM is composed of a magnetic circuit and coil assembly When a current passes through the coil placed in the magnetic fiel
4. icient of friction is calculated based upon the weight of the slider 40g It is therefore necessary to take the weight of the attached samples into consideration When measuring the coefficient of friction between samples a maximum thickness of 1mm of sample material may be attached 2 Installing the Rubber Slider 1 Remove the two bolts which hold the bottom cover in place 2 Use screws to fix the spacers in place 2 locations Refer to diagram 1 Install the rubber slider Refer to diagram 2 Diagram 1 Diagram 2 3 Installing the 6 Point Bowl Slider 1 Use a slider holder to install the slider as illustrated in the diagram 2 Install the 6 point bowl slider in the same way 4 Check the Power Supply Voltage After turning on the power check to make sure that the LED display reads 0 000 The batteries need to be replaced if the LED display reads e e To replace the batteries use the supplied screwdriver to remove the screws which hold the battery case cover in place The battery case cover is located on the bottom of the main unit Pull out the battery holder and replace the 4 batteries Use only new size AA alkaline batteries After replacing the batteries insert the holder back into the unit replace the cover and then replace the screws which hold it in place 5 Measurement Method Place the object to be measured upon a horizontal surface and set the unit down gently The center of the slider is located direct
5. ly below the LED display panel Press the Measure button The value displayed is the coefficient of static friction 6 The Average Function Press the average button after marking number of measurements Max 769 times The coefficient of static friction is a rough guide to the friction between objects Measured values may vary depending upon conditions under which measurements are performed Therefore taking the average of several measurements provides a more accurate value 6 Notes Regarding Handling of the Friction Meter Do not drop the unit or subject it to strong physical shocks e Do not allow the unit to become wet e The sensor and VCM sections are extremely delicate Do not disassemble them e In order to avoid dust contamination store the unit in its case when it will not be used for an extended period of time e The condition of the slider s surface has a great effect upon measurement values Handle it with great care e Avoid making measurements on vibrating surfaces 7 Characteristics and Performance Driving Force gf VCM Current Driving Force Characteristics e Driving force generated bv VCM calculated using a strain gauge Actual measurement example TA 50 100 150 200 Current mA Driving Force Constant gf mA 0 34 VCM Current Driving Force Constant Characteristics 0 33 R e VCM d
6. riving force constant calculated using a strain gauge pusa Within 1 Actual measurement example 50 109 150 200 Current mA Error Rate Relationship Between Coefficient of Static Friction and Cal culation Error Maximum e Calculation error due to circuit resolution 1 0 1 5 Coefficient of Static Friction 10 8 Specifications Model HEIDON TRIBO GEAR uS Type 94i Measurement Range Coefficient of static friction 0 000 1 300 Measurement Precision Refer to graphs provided in part 7 Characteristics and Performance Displav Resolution 0 01 Detector VCM Photo sensor Displav 7 Segment LED RED 4 digits Materials Main Unit ABS Aluminum Slider Brass hard chrome treated 40g Power Supplv Alkaline batteries 4 size AA Dimensions 188mm x 62mm x 65mm 11 KETT ELECTRIC LABORATORV 1 8 1 Minami Magome Ota Ku Tokyo 143 8507 Japan Tel 81 3 3776 1121 Fax 81 3 3772 3001 URL http www kett co jp E mail overseas kett co jp 0602 0201 100
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