1、Designation: G143 03 (Reapproved 2018)Standard Test Method forMeasurement of Web/Roller Friction Characteristics1This standard is issued under the fixed designation G143; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 andkinet
3、ic 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 bek
4、nown.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.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 establish
5、 appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for
6、theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1894 Test Method for Static and Kinetic Coefficients ofFriction of
7、 Plastic Film and SheetingD3108/D3108M Test Method for Coefficient of Friction,Yarn to Solid MaterialE8/E8M Test Methods for Tension Testing of Metallic Ma-terialsE122 Practice for Calculating Sample Size to Estimate, WithSpecified Precision, the Average for a Characteristic of aLot or ProcessE177 P
8、ractice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodG40 Terminology Relating to Wear and ErosionG115 Guide for Measuring and Reporting Friction Coeffi-cientsG117 Guide for Calculating and R
9、eporting Measures ofPrecision Using Data from Interlaboratory Wear or Ero-sion Tests (Withdrawn 2016)3G163 Guide for Digital Data Acquisition in Wear andFriction Measurements (Withdrawn 2016)33. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 blocking, nunintentional adhesion bet
10、ween plasticfilms or between a film and another surface. D8833.1.2 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 theinterf
11、ace between two bodies when, under the action ofexternal force, one 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 i
12、n the magnitudes offriction force and relative velocity between two 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
13、.5.1 DiscussionClassical or true stick-slip, in whicheach cycle consists 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, can
14、1This 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 June 1, 2018. Published July 2018. Originally approvedin 1996. Last previous edition approved in 2013 as G143 03 (2013). D
15、OI:10.1520/G0143-03R18.2For 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 standards Document Summary page onthe ASTM website.3The last approved version of this his
16、torical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Deci
17、sion on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1occur when the kinetic coefficient of friction decreases gradu-ally with increasing velocity within a certain velocity rang
18、e. 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 bodieswhich comprise a sliding, rolling, or abrasive contac
19、t, or abody subjected to impingement or cavitation. G403.1.6.1 DiscussionContacting triboelements may be indirect contact, or may be separated by an intervening lubricant,oxide, or other film that affects tribological interactions be-tween them.3.1.7 tribosystem, nany system that contains one or mor
20、etriboelements, 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 frictioncharacteristics of a flexible web as it slides on a cylindricalsurface. The web conforms to the cylind
21、rical 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 is affixed to a forcemeasuring device. A mass is applied to the free end of the stripand the strip is pul
22、led 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 (roller) is continuously measuredand recorded. The static and kinetic coefficients of friction arecalculated f
23、rom 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 web materials. Flexible webs such as plastic sheeting,paper, elastomers, metal foils, and cloth are often t
24、ransported inmanufacturing processes by combinations of driving and idlerrollers. The friction characteristics of the web/roller interfaceoften affects the web transport process. If the web/rollerfriction is too low, the web can slip on the rollers and bedamaged or damage the roller. High friction o
25、n 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 (highfriction). Conversely this test method can assess web materialsor web surface coatings such as waxes
26、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 roller, this is an appropriate test to use to measure the frictioncharacteristics of the roller/web coup
27、le.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 friction couple,6.1.2 A stationary cylindrical surface to be used as onemember of the friction couple,6.1.3 A
28、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 strain gage or similar force transducers are acceptable.The device should be linear in the force range an
29、ticipated 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 and should have overload protection.The friction force during the entire test should be recorded.(WarningD
30、igital filters can alter the force data to the pointFIG. 1 Schematic of Capstan Friction TestFIG. 2 Use of Tensile Test Machine to Perform the Capstan Fric-tion TestG143 03 (2018)2where the data are not valid. Analog strip chart recorders havebeen shown to be acceptable recording devices for this te
31、stmethod. (See Guide G163 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 b
32、ethe same as the tribosystem of interest. If materials are beingevaluated without simulating a particular tribosystem, the testroller can be the same as the roller used in the interlaboratorytests of this test method: 100-mm diameter (100 mm long),50-m thick hard coated (thick hard anodize) 6061-T6
33、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 motor to pull the test strip. The cylinder isstationary. Any device with controlled acceleration and velo
34、c-ity is acceptable.Aball 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-wheeling rolling element bearing to transfer the motionfrom a vertical to horizontal plane (see Fig. 2).NOTE
35、 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 Tensioning MassOrdinary masses from balances andsimilar laboratory equipment are suitable for tensioning.
36、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 of the test strip. If lateral slip occurs in a particular test, theresults will probably be different from
37、 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. Both friction and temperature at the timeof testing shall be recorded and, if the tribosystem that is to besim
38、ulated 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 testing. Twenty four hours is a minimum incubation period.6.7 CalibrationA suitable system for calibration of the
39、force 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 transducer is linearly proportional to the appliedforce over the range of forces to be measured. Calibrate
40、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 is consistentwith the application that is under simulation. Cut virgin stripsfrom the test web as the other
41、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 E122 or other statistical methodscan be used to determine the necessary number of testreplicates. Three is the minimum.7.1.2 D
42、o 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 such a fashion that there is no edge burr onthe side that contacts the roller. This is extremely important.E
43、nsure 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-edgedrazor blades to a block of wood spaced at the desired stripwidth. This device can be used to cut samples from th
44、in 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 the bridle end of the force transducer; drape the strip over thetest roller (cylindrical surface), and apply t
45、he 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. Ensure that the strip ispulled straight (aligned with the web tension) within 61 mm.Markers can be used on the
46、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, and free-end tension on thestrip. It is recommended that values for these parameters beselected to simulate
47、 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 worst case of 10 % of the web speed. (Forexample, if a web conveyance system is being simulated witha web speed
48、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 web with the conforming cylindrical surface.Users can test the velocity limits of their system, but 0.1 m/s is
49、about the limit of the systems that were used in interlaboratorytesting. A continuous loop test (Test Method D3108/D3108M)is more appropriate for high sliding velocities.7.3.2 Sliding DistanceIf the goal of this test method is thestatic coefficient of friction, the test can be stopped after a fewFIG. 3 Method for Gripping the Test StripG143 03 (2018)3millimetres 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 thetest
