1、Designation: G 143 03 (Reapproved 2004)Standard Test Method forMeasurement of Web/Roller Friction Characteristics1This standard is issued under the fixed designation G 143; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the simulation of a roller/webtransport tribosystem and the measurement of the static andki
3、netic coefficient of friction of the web/roller couple whensliding occurs between the two. The objective of this testmethod is to provide users with web/roller friction informationthat can be used for process control, design calculations, andfor any other function where web/roller friction needs to
4、beknown.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to estab
5、lish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 883 Terminology Relating to PlasticsD 1894 Test Method for Static and Kinetic Coefficients ofFriction of Plastic Film and SheetingD 3108
6、Test Method for Coefficient of Friction, Yarn toSolid MaterialE 8 Test Methods for Tension Testing of Metallic MaterialsE 122 Practice for Choice of Sample Size to Estimate, Witha Specified Tolerable Error, the Average for Characteristicof a Lot or ProcessE 177 Practice for Use of the Terms Precisio
7、n and Bias inASTM Test MethodsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodG 40 Terminology Relating to Wear and ErosionG 115 Guide for Measuring and Reporting Friction Coeffi-cientsG 117 Guide for Calculating and Reporting Measures ofPrecision Usi
8、ng Data from Interlaboratory Wear or Ero-sion TestsG 163 Guide for Digital Data Acquisition in Wear andFriction Measurements3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 blocking, nunintentional adhesion between plasticfilms or between a film and another surface. D 8833.1.2
9、coeffcient of friction, , nin tribologythe dimen-sionless ratio of the friction force (F) between two bodies to thenormal force (N) pressing these bodies together. G403.1.3 friction force, nthe resisting force tangential to theinterface between two bodies when, under the action ofexternal force, one
10、 body moves or tends to move relative to theother. G403.1.4 kinetic coeffcient of friction, nthe coefficient offriction under conditions of macroscopic relative motion be-tween two bodies. G403.1.5 stick-slip, na cyclic fluctuation in the magnitudes offriction force and relative velocity between two
11、 elements insliding contact, usually associated with a relaxation oscillationdependent on elasticity in the tribosystem and on a decrease ofthe coefficient of friction with onset of sliding or with increaseof sliding velocity. G403.1.5.1 DiscussionClassical or true stick-slip, in whicheach cycle con
12、sists of a stage of actual stick followed by astage of overshoot slip, requires that the kinetic coefficient islower than the static coefficient. A modified form of relaxationoscillation, with near-harmonic fluctuation in motion, canoccur when the kinetic coefficient of friction decreases gradu-ally
13、 with increasing velocity within a certain velocity range. Athird type of stick-slip can be due to spatial periodicity of thefriction coefficient along the path of contact. Random varia-tions in friction force measurement do not constitute stick-slip.3.1.6 triboelement, none of two or more solid bod
14、ieswhich comprise a sliding, rolling, or abrasive contact, or abody subjected to impingement or cavitation. G401This test method is under the jurisdiction of ASTM Committee G02 on Wearand Erosion and is the direct responsibility of Subcommittee G02.50 on Friction.Current edition approved Nov 1, 2004
15、. Published November 2004. Originallyapproved in 1996. Last previous edition approved in 2003 as G 143 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standa
16、rds Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.6.1 DiscussionContacting triboelements may be indirect contact, or may be separated by an intervening lubricant,oxide, or other film tha
17、t affects tribological interactions be-tween them.3.1.7 tribosystem, nany system that contains one or moretriboelements, including all mechanical, chemical, and envi-ronmental factors relevant to tribological behavior. G404. Summary of Test Method4.1 This test method can be used to measure the frict
18、ioncharacteristics of a flexible web as it slides on a cylindricalsurface. The web conforms to the cylindrical surface in the areaof wrap.4.2 The test method is conducted on a narrow web or striptaken from a web of interest. One end of the strip is drapedover a stationary cylinder and the other end
19、is affixed to a forcemeasuring device. A mass is applied to the free end of the stripand the strip is pulled by a mechanism that moves the forcetransducer perpendicular to the long axis of the cylindricalsurface. The force encountered in pulling the strip in contactwith the stationary cylinder (roll
20、er) is continuously measuredand recorded. The static and kinetic coefficients of friction arecalculated from the force measured by the force transducer.5. Significance and Use5.1 This test method is intended to simulate the slip of aflexible web on a roller in a machine or tribosystem thatconveys we
21、b materials. Flexible webs such as plastic sheeting,paper, elastomers, metal foils, and cloth are often transported inmanufacturing processes by combinations of driving and idlerrollers. The friction characteristics of the web/roller interfaceoften affects the web transport process. If the web/rolle
22、rfriction is too low, the web can slip on the rollers and bedamaged or damage the roller. High friction on the other hand,can lead to steering problems and overloading of drivingmotors.5.2 This test method can be used to rank rollers for theirability to resist slip versus a particular web material (
23、highfriction). Conversely this test method can assess web materialsor web surface coatings such as waxes and lubricants. In thislatter case, the goal may be a low-friction product made froma web (film, magnetic media, paper, and so forth).5.3 If a tribosystem involves transport of a flexible web ona
24、 roller, this is an appropriate test to use to measure the frictioncharacteristics of the roller/web couple.6. Apparatus6.1 Two possible configurations of the test are shown inFigs. 1 and 2. The essential features of the apparatus are:6.1.1 A force measuring device attached to one member ofthe frict
25、ion couple,6.1.2 A stationary cylindrical surface to be used as onemember of the friction couple,6.1.3 A system to move the flexible strip (web) member ofthe friction couple, and6.1.4 Masses to be used to tension the free end of the teststrip.6.2 Force MeasurementCommercially available or home-made
26、strain gage or similar force transducers are acceptable.The device should be linear in the force range anticipated intesting and the transducer shall be calibrated with knownmasses or a similar system for each use.6.2.1 Force transducers shall be accurate within 1 % of therated scale of the device a
27、nd should have overload protection.The friction force during the entire test should be recorded.(WarningDigital filters can alter the force data to the pointwhere the data are not valid. Analog strip chart recorders havebeen shown to be acceptable recording devices for this testmethod. (See Guide G
28、163 for details on digital data acquisi-tion)6.3 Cylindrical SurfaceThe recommended diameter of thetest cylinder should be the same diameter as the rollers orcurved surface that is simulated in the friction test. Thecylinder surface texture and material of construction should bethe same as the tribo
29、system of interest. If materials are beingevaluated without simulating a particular tribosystem, the testroller can be the same as the roller used in the interlaboratoryFIG. 1 Schematic of Capstan Friction TestFIG. 2 Use of Tensile Test Machine to Perform the CapstanFriction TestG 143 03 (2004)2test
30、s of this test method: 100-mm diameter (100 mm long),50-m thick hard coated (thick hard anodize) 6061-T6 alumi-num with a surface roughness of 0.75 to 1 m Ra (measuredparallel to the cylinders axis; surface was lathe generated).6.4 Sliding MotionThe device shown schematically inFig. 1 uses a linear
31、motor to pull the test strip. The cylinder isstationary. Any device with controlled acceleration and veloc-ity is acceptable. A ball screw driven by a variable speed motoris suitable as is the crosshead on a tensile testing machine. Inthe latter case, it may be necessary to use a sheave with afree-w
32、heeling rolling element bearing to transfer the motionfrom a vertical to horizontal plane (see Fig. 2).NOTE 1Some devices rotate the cylinder and hold the web with aforce transducer. This was done in interlaboratory tests and produced thesame results as pulling the web over a stationary cylinder.6.5
33、 Tensioning MassOrdinary masses from balances andsimilar laboratory equipment are suitable for tensioning. It isimperative to attach the masses and the friction transducerswith a device that prevents lateral motion of the test strip.Bridle devices such as the one shown in Fig. 3 allow a straightpull
34、 of the test strip. If lateral slip occurs in a particular test, theresults will probably be different from a test in which thisunwanted slip does not occur.6.6 Test EnvironmentThe friction characteristics of someweb/roller couples can be affected by the ambient temperatureand relative humidity. Bot
35、h friction and temperature at the timeof testing shall be recorded and, if the tribosystem that is to besimulated involves some special environment, then this shouldbe simulated. Test samples should be incubated for an adequatetime to reach equilibrium in the intended test environment priorto testin
36、g. Twenty four hours is a minimum incubation period.6.7 CalibrationA suitable system for calibration of theforce transducer is to mount the transducer vertically andsimply apply a series of known weights on the transducer withthe force recording device running. Make sure that the outputof the force
37、transducer is linearly proportional to the appliedforce over the range of forces to be measured. Calibrate usingweights that produce force comparable in magnitude to theforces anticipated in the friction test.7. Test Procedure7.1 Specimen Preparation:7.1.1 Clean the roller surface in a manner that i
38、s consistentwith the application that is under simulation. Cut virgin stripsfrom the test web as the other friction member. Take care notto fingerprint or alter the test surface in handling the web.Convenient sample dimensions are 25 mm wide with a lengthof about 500 mm. Practice E 122 or other stat
39、istical methodscan be used to determine the necessary number of testreplicates. Three is the minimum.7.1.2 Do not clean the web specimen unless that is part ofthe study. If paper or plastic sheets are being tested, they shouldbe tested with untouched as-manufactured surfaces. Cut theweb specimen in
40、such a fashion that there is no edge burr onthe side that contacts the roller. This is extremely important.Ensure that the edges of the strip are parallel and in the desiredorientation with respect to the long axis of the host web. Auseful tool for sample preparation is to affix two single-edgedrazo
41、r blades to a block of wood spaced at the desired stripwidth. This device can be used to cut samples from thin plastic,cloth, and paper webs. The interlaboratory tests were con-ducted with web strips that were 25 mm in width and 500 mmlong.7.2 Mounting the SpecimenAffix one end of the web stripto th
42、e bridle end of the force transducer; drape the strip over thetest roller (cylindrical surface), and apply the desired tension-ing mass. Avoid clamp systems that have significant elasticity.If a tensile-testing machine is used to produce motion, flexiblesteel cable can be used to pull the strip. Ens
43、ure that the strip ispulled straight (aligned with the web tension) within 61 mm.Markers can be used on the test roller to determine if trackingis within the 1-mm limit.7.3 Setting the Sliding Parameters:7.3.1 VelocityThe capstan friction tester allows selectionof sliding velocity, sliding distance,
44、 and free-end tension on thestrip. It is recommended that values for these parameters beselected to simulate the system of interest. The sliding velocitybetween webs and transport or drive rollers in manufacturingmachines is usually in the range from a fraction of a percent ofthe web speed to a wors
45、t case of 10 % of the web speed. (Forexample, if a web conveyance system is being simulated witha web speed of 1 m/s, a low-end test velocity may be 5 mm/sand the high-end test velocity 0.1 m/s.) There is a velocity limitin this type of test. High speed will cause instability in thecontact of the we
46、b with the conforming cylindrical surface.Users can test the velocity limits of their system, but 0.1 m/s isabout the limit of the systems that were used in interlaboratorytesting. A continuous loop test (Test Method D 3108) is moreappropriate for high sliding velocities.7.3.2 Sliding DistanceIf the
47、 goal of this test method is thestatic coefficient of friction, the test can be stopped after a fewmillimetres of sliding. If the goal of this test method is both thestatic and the kinetic coefficients of friction, it is desirable toslide for as long a distance as the test setup will allow. With the
48、test setup shown in Fig. 1, the maximum travel on commerciallinear motors is about 0.5 m. The allowable motion on thepulling device is the limiting factor on sliding distance.Interlaboratory tests were conducted with a sliding distance of150 mm. This is the recommended sliding distance for this test
49、.7.3.3 Test TensionThe tensioning mass affixed to the freeend of the strip specimen can be any magnitude that willsimulate the system of interest. The practical limit is the massthat will produce tensile yielding or breaking of the test strip.FIG. 3 Method for Gripping the Test StripG 143 03 (2004)3The maximum tension that has been used in the ASTMinterlaboratory tests was 150 N on a 25-mm wide test strip.Repeatability tests were conducted with a tension of 4.45 N onthe 25 mm-wide test strip. It is advisable to test at a variety ofweb tensions if this i
