1、Designation: G 176 03 (Reapproved 2009)Standard Test Method forRanking Resistance of Plastics to Sliding Wear UsingBlock-on-Ring Wear TestCumulative Wear Method1This standard is issued under the fixed designation G 176; the number immediately following the designation indicates the year oforiginal a
2、doption or, in the case of revision, the year of 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 laboratory procedures for de-termining the re
3、sistance of plastics to sliding wear. The testutilizes a block-on-ring friction and wear testing machine torank plastics according to their sliding wear characteristicsagainst metals or other solids.1.2 An important attribute of this test is that it is veryflexible.Any material that can be fabricate
4、d into, or applied to,blocks and rings can be tested. Thus, the potential materialscombinations are endless. In addition, the test can be run withdifferent gaseous atmospheres and elevated temperatures, asdesired, to simulate service conditions.1.3 Wear test results are reported as the volume loss i
5、n cubicmillimetres for the block and ring. Materials of higher wearresistance will have lower volume loss.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety concer
6、ns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 618 Practice for Conditioning Plastics
7、for TestingD 2714 Test Method for Calibration and Operation of theFalex Block-on-Ring Friction and Wear Testing MachineE 122 Practice for Calculating Sample Size to Estimate,With Specified Precision, the Average for a Characteristicof a Lot or ProcessE 177 Practice for Use of the Terms Precision and
8、 Bias inASTM Test MethodsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodG40 Terminology Relating to Wear and ErosionG77 Test Method for Ranking Resistance of Materials toSliding Wear Using Block-on-Ring Wear Test3. Terminology3.1 Definitions:3.1.1 we
9、ardamage to a solid surface, generally involvingprogressive loss of material, due to relative motion betweenthat surface and a contacting substance or substances. G404. Summary of Test Method4.1 A test plastic block is loaded against a metal test ringthat rotates at a given speed for a given number
10、of revolutions.Block scar volume is calculated from the block scar width. Thefriction force required to keep the block in place may becontinuously measured during the test with a load cell. Whenthis is done, the friction force data are combined with normalforce data to obtain values for the coeffici
11、ent of friction andreported.5. Significance and Use5.1 The significance of this test method in any overallmeasurement program directed toward a service applicationwill depend on the relative match of test conditions to theconditions of the service application.5.2 This test method prescribes the test
12、 procedure andmethod of calculating and reporting data for determining thesliding wear resistance of plastics, using cumulative volumeloss.5.3 The intended use of this test is for coarse screening ofplastics in terms of their resistance to sliding wear.6. Apparatus and Test Specimens6.1 Test Schemat
13、icA schematic of the block-on-ring weartest geometry is shown in Fig. 1. In the figure, the friction loadcell is enlarged.6.2 Test RingA typical test ring is shown in Fig. 2. Thetest ring must have an outer diameter of 34.99 6 0.025 mm(1.377 6 0.001 in.) with an eccentricity between the inner andout
14、er surfaces of no greater than 0.00125 mm (0.0005 in.). For1This test method is under the jurisdiction of ASTM Committee G02 on Wearand Erosion and is the direct responsibility of Subcommittee G02.40 on Non-Abrasive Wear.Current edition approved May 1, 2009. Published May 2009. Originallyapproved in
15、 2003. Last previous edition approved in 2003 as G 17603.2For 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.1Cop
16、yright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.couples where surface condition is not under study, it isrecommended that the outer diameter be a ground surface witha roughness of 0.152 to 0.305 m (6 to 12 in.) rms or centerline average
17、(CLA), in the direction of motion. However,alternate surface conditions may be evaluated in the test, asdesired. It should be kept in mind that surface condition canhave an effect on sliding wear results.NOTE 1A commonly used test ring is a carburized 4620 steel havinga hardness of 60 HRC or higher.
18、6.3 Test BlockAtest block is shown in Fig. 3. Block widthis 6.35 + 0.000, 0.025 mm (0.250 + 0.000, 0.001 in.).6.4 Optical Device (or equivalent), with metric or Englishunit calibration, is also necessary so that scar width can bemeasured with a precision of 0.01 mm (0.0004 in.) or equiva-lent.7. Rea
19、gents7.1 Reagents may include the following:NOTE 2Organic cleaners should be used with caution as they mayreact with the plastic being tested.7.1.1 Methanol.7.1.2 Eye Glass Cleaner.8. Preparation and Calibration of Apparatus8.1 Run the calibration procedure that is in Test MethodD 2714 to ensure goo
20、d mechanical operation of the testequipment.9. Procedure9.1 Condition the test specimens at 23 6 2C (73.4 63.6F) and 50 6 5 % relative humidity for not less than 40 hprior to testing in accordance with Procedure A of PracticeD 618 for those samples where conditioning is required.9.2 The recommended
21、test conditions are the standardlaboratory atmosphere of 23 6 2C (73.4 6 3.6F) and 50 65 % relative humidity.9.3 Clean the ring using a procedure that will remove anyscale, oil film, or residue without damaging the surface. Thefollowing procedure is recommended: clean the ring in asuitable solvent,
22、ultrasonically, if possible; a methanol rinsemay be used to remove any traces of solvent residue.Allow therings to dry completely. Handle the ring with clean, lint-freecotton gloves from this point on.9.4 For the plastic block, the following cleaning procedureis recommended: Clean the plastic block
23、with methanol.Allowthe blocks to dry completely. After cleaning, handle the blockwith clean, lint-free cotton gloves. Other procedures may beused provided they do not affect the plastic. If an applicationunder study uses a plastic in the molded condition, it is advisedto test a block with the test s
24、urface in the molded condition.The wear of a molded surface may be different from the wearof a machined surface.9.5 Make surface texture and surface roughness measure-ments across the width of the ring, as necessary. Note that asurface profile does not completely describe a surface topol-ogy. Scanni
25、ng electron micrographs may be used, as desired, toaugment the description of the wear surfaces. Clean the ringagain, if necessary, as in 9.3.9.6 Demagnetize the ring and ferrous assembly.9.7 Measure the block width and ring diameter to thenearest 0.025 mm (0.001 in.).9.8 Clean the self-aligning blo
26、ck holder, ring shaft, andsurrounding fixtures with solvent.9.9 Put the self-aligning block holder on the block. Apply athin layer of lubricant to the self-aligning holder. Use of anon-migrating product is suggested.9.10 Place the block in position on the machine and, whileholding the block in posit
27、ion, place the ring on the shaft andlock the ring in place, using a method in accordance with therequirements of the specific machine design.9.11 Center the block on the ring while placing a lightmanual pressure on the lever arm to bring the block and ringinto contact. Be sure the edge of the block
28、is parallel to theedge of the ring and that the mating surfaces are perfectlyaligned. This is accomplished by making sure the specimenholder is free during mounting so that the quarter segment canproperly seat itself. Release the pressure on the lever arm.9.12 Place the required weights on the load
29、bale and adjustthe lever arm in accordance with the requirements of thespecific machine design to provide a load of 44.3 N (10 lbf) atthe block/ring interface. Then remove the load by raising theweights.9.13 Set the revolution counter to zero.9.14 Gently lower the weights to apply the required load.
30、9.15 If using a variable speed machine, turn on the machineand slowly increase the power to the drive motor until the ringstarts to rotate, and record the “static” friction force. Continueto increase the rate of rotation to 200 rpm. If using a fixedspeed machine, simply turn on the machine.9.16 Duri
31、ng the test, record the friction force.9.17 Stop the test manually or automatically after 240 000revolutions (20 h).9.18 A final “static” friction force may be measured with avariable speed machine. Leaving on the full load, wait 3 min 610 s, then turn on the machine and slowly increase the powerto
32、the drive motor until the ring starts to rotate, recording thefinal “static” friction force. Then turn off the motor.9.19 Remove the block and ring and clean. For metals, usea suitable solvent. For plastics, remove loose debris with a drysoft brush.9.20 Make surface roughness measurements and profil
33、ome-ter traces across the width of the block and the ring as desired.Atrace along the long axis of the block, through the wear scar,is also useful to verify the scar depth and shape.FIG. 1 Test SchematicG 176 03 (2009)29.21 Measure the scar width on the test block in the centerand 1 mm (0.04 in.) aw
34、ay from each edge. These measure-ments shall be to the nearest 0.01 mm (0.0004 in.). Record theaverage of the three readings. Sometimes a lip of plasticallydeformed material will extend over the edge of the wear scar.When measuring scar width, try to visually ignore this materialor measure the scar
35、width in an area where this is not aproblem.9.22 Tapered scars indicate improper block alignment dur-ing testing. If the three width measurements on a given scarhave a coefficient of variation of greater than 10 %, the testshall be declared invalid. For further discussion of measure-ment problems se
36、e 9.21, 9.22, and Fig. 4 in Test Method G77.10. Calculation10.1 Calculation of Block Scar Volume:10.1.1 Block scar volume may be derived from block scarwidth by using Table 1 (applicable only when ring diameter is34.99 6 0.025 mm (1.377 6 0.001 in.) and scar length (blockwidth) is 6.35 + 0.000, 0.02
37、5 mm (0.250 + 0.000, 0.001in.).10.1.2 The preferred method of calculating block scarvolume is by using the formula shown in Fig. 4. This formulamay be programmed on a calculator or computer.10.1.3 Block scar volume is not calculated generally fromblock mass loss because block mass is subject to effe
38、cts ofmaterial transfer. Keeping this in mind, block mass loss may beinterpreted semi-quantitatively in a comparative evaluation ofvarious material couples. If the block scar cannot be accuratelymeasured following 9.21, a scar volume should not be calcu-lated, but a notation made of the problem, for
39、 example,material transfer, plastic deformation, and so forth.NOTEThe outer diameter and concentricity with the inner diameter are the only critical parameters. The inner diameter is optional depending onmachine design. The inside diameter taper shown fits a number of standard machines.FIG. 2 Test R
40、ingG 176 03 (2009)310.2 Calculate coefficient of friction values from frictionforce values as follows: 5FW(1)where: = coefficient of friction,F = measured friction force, N (lbf), andW = applied load, 44.3 N (10 lbf).10.3 Calculate ring volume loss as follows:volume loss 5ring mass lossring density(
41、2)10.3.1 If the ring gains mass during the test, the volume lossis reported as zero with a notation that weight gain occurred.Ring mass loss can be affected by transfer of the plastic to themetal surface. If plastic transfer to the ring is obvious, then aring scar volume should not be calculated fro
42、m the weight lossmeasurement, but a notation should be made that plastictransfer occurred. If there are obvious signs of abrasion of thering surface, such as scratches or grooving, this should also benoted. In this case profilometry may be used to measurematerial loss.11. Report11.1 Report any unusu
43、al event or an overload shutoff of themachine (on some machines it is possible to have an automaticshutoff at a preset frictional load). If the machine malfunctionsor a test block has a tapered scar, the data shall not be used, andthe test shall be rerun.11.2 Report the following:11.2.1 Test Paramet
44、ers:11.2.1.1 Block material,11.2.1.2 Ring material and hardness (whenever applicable),11.2.1.3 Ring and block initial surface roughness, and11.2.1.4 Number of replicates.11.2.2 ResultsReport the average and the coefficient ofvariation of the following (the coefficient of variation is thestandard dev
45、iation divided by the average; it is expressed as apercent).11.2.2.1 Block scar width, mm,11.2.2.2 Block scar volume, mm3, calculated from scarwidth, and11.2.2.3 Ambient conditions, if other than normal labora-tory conditions.11.2.3 Reporting Optional:11.2.3.1 Final surface roughness of block and ri
46、ng,11.2.3.2 Ring heat treatment, and11.2.3.3 Initial “static” and dynamic coefficients of frictionand final “static” and dynamic coefficients of friction.12. Precision and Bias12.1 The precision and bias of the measurements obtainedwith this test procedure will depend upon strict adherence tothe sta
47、ted test procedure.12.2 The consistency of agreement in repeated tests on thesame material will depend upon material consistency, machineand material interaction, and close observation of the test by acompetent machine operator.12.3 PrecisionIn interlaboratory tests the coefficient ofvariation betwe
48、en laboratories (reproducibility) and the coef-ficient of variation within a laboratory (repeatability) aresimilar but vary with the material. Coefficients were found torange from less than 10 % up to 100 % with a mean value ofG 176 03 (2009)4TABLE 1 Block Scar Widths and Volumes for Blocks 6.35-mm
49、Wide Mated Against Rings 34.99 mm in DiameterBlock ScarWidth(mm)Volume(mm3)Width(mm)Volume(mm3)Width(mm)Volume(mm3)Block ScarWidth(mm)Volume(mm3)Width(mm)Volume(mm3)Width(mm)Volume(mm3)0.30 0.0008 1.01 0.0312 1.72 0.1541 2.42 0.4295 3.12 0.9212 3.83 1.70620.31 0.0009 1.02 0.0321 1.73 0.1568 2.43 0.4348 3.13 0.9301 3.84 1.71960.32 0.0010 1.03 0.0331 1.74 0.1595 2.44 0.4402 3.14 0.9391 3.85 1.73310.33 0.0011 1.04 0.0340 1.75 0.1623 2.45 0.4456 3.15 0.9481 3.86 1.74670.34 0.0012 1.05 0.0350 1.76 0.1651 2.46 0.4511 3.16 0.9572 3.87 1.76030.35 0.0013 1.06 0.036
