1、Designation: G143 03 (Reapproved 2013)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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1894 Test Method for Static and Kinetic Coefficients ofFriction of Plastic Film and SheetingD3108 Test Me
6、thod for Coefficient of Friction, Yarn to SolidMaterialE8 Test Methods for Tension Testing of Metallic MaterialsE122 Practice for Calculating Sample Size to Estimate, WithSpecified Precision, the Average for a Characteristic of aLot or ProcessE177 Practice for Use of the Terms Precision and Bias inA
7、STM 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 Reporting Measures ofPrecision Using Data from Inter
8、laboratory Wear or Ero-sion TestsG163 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. D8833.1.2 coeffcient of fricti
9、on, , 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 body moves or tends
10、 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 elements insliding
11、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 consists of a stage of
12、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 with increasing vel
13、ocity 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 bodieswhich comprise a
14、sliding, rolling, or abrasive contact, or abody subjected to impingement or cavitation. G403.1.6.1 DiscussionContacting triboelements may be in1This test method is under the jurisdiction of ASTM Committee G02 on Wearand Erosion and is the direct responsibility of Subcommittee G02.50 on Friction.Curr
15、ent edition approved Nov. 15, 2013. Published November 2013. Originallyapproved in 1996. Last previous edition approved in 2009 as G14303(2009). DOI:10.1520/G0143-03R13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annua
16、l Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1direct contact, or may be separated by an intervening lubricant,oxide, or othe
17、r film that 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
18、 the frictioncharacteristics 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
19、other end 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 cyli
20、nder (roller) 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 that
21、conveys web 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
22、 web/rollerfriction 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
23、material (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 flexib
24、le web ona 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 o
25、fthe friction 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
26、home-made 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 th
27、e device and 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. (Se
28、e 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 bethe same as
29、the tribosystem of interest. If materials are beingFIG. 1 Schematic of Capstan Friction TestFIG. 2 Use of Tensile Test Machine to Perform the Capstan Fric-tion TestG143 03 (2013)2evaluated without simulating a particular tribosystem, the testroller can be the same as the roller used in the interlabo
30、ratorytests 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
31、 a linear motor to pull the test strip. The cylinder isstationary. Any device with controlled acceleration and veloc-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
32、 afree-wheeling 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 cyli
33、nder.6.5 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 stra
34、ightpull 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 humid
35、ity. Both 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 priort
36、o testing. 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 th
37、e force 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 manne
38、r that is 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 E122 or oth
39、er statistical 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 speci
40、men in 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-ed
41、gedrazor 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 str
42、ipto the 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 str
43、ip. Ensure 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 di
44、stance, 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
45、 a worst 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
46、 the web 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 D3108) is moreappropriate for high sliding velocities.7.3.2 Sliding Distance
47、If the 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. Wi
48、th thetest 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 thi
49、s test.FIG. 3 Method for Gripping the Test StripG143 03 (2013)37.3.3 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.The 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 t
