1、Designation: G 176 03Standard 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 adoption or, in the
2、 case of revision, the year of 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 laboratory procedures for de-termining the resistance of plast
3、ics 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 fabricated into, or appli
4、ed 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 in cubicmillimetr
5、es 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 concerns, if any, asso
6、ciated 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:D 618 Practice for Conditioning Plastics for Testing2D 271
7、4 Test Method for Calibration and Operation of theFalex Block-on-Ring Friction and Wear Testing Machine3E 122 Practice for Calculating Sample Size to Estimate,With a Specified Tolerable Error, the Average for Charac-teristic of a Lot or Process4E 177 Practice for Use of the Terms Precision and Bias
8、inASTM Test Methods4E 691 Practice for Conducting an Inter-laboratory Study toDetermine the Precision of a Test Method4G 40 Terminology Relating to Wear and Erosion5G 77 Test Method for Ranking Resistance of Materials toSliding Wear Using a Block-on-Ring Wear Test5G 117 Guide for Calculating and Rep
9、orting Measures ofPrecision Using Data from Interlaboratory Wear or Ero-sion Tests23. Terminology3.1 Definition:3.1.1 weardamage to a solid surface, generally involvingprogressive loss of material, due to relative motion betweenthat surface and a contacting substance or substances. G404. Summary of
10、Test Method4.1 A test plastic block is loaded against a metal test ringthat rotates at a given speed for a given number 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 l
11、oad cell. Whenthis is done, the friction force data are combined with normalforce data to obtain values for the coefficient 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 th
12、e relative match of test conditions to theconditions of the service application.5.2 This test method prescribes the test 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
13、coarse screening ofplastics in terms of their resistance to sliding wear.6. Apparatus and Test Specimens6.1 Test SchematicA 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. Thete
14、st ring must have an outer diameter of 34.99 6 0.025 mm1This 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 June 10, 2003. Published July 2003.2Annual Book of ASTM St
15、andards, Vol 08.01.3Annual Book of ASTM Standards, Vol 05.01.4Annual Book of ASTM Standards, Vol 14.02.5Annual Book of ASTM Standards, Vol 03.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.(1.377 6 0.001 in.) with an eccentricity
16、 between the inner andouter surfaces of no greater than 0.00125 mm (0.0005 in.). Forcouples 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 (CLA), in the direction of
17、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.6.3 Test BlockA test block
18、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. Reagents7.1 Reagents may incl
19、ude 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 good mechanical operation of
20、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 test conditions are the st
21、andardlaboratory 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, ultrasonically, if possibl
22、e; 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 with methanol. Allowthe b
23、locks 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 surface in the molded con
24、dition.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. Scanning electron micrographs
25、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 block holder, ring shaft, a
26、ndsurrounding 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 position, place the ring on t
27、he 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 is parallel to theedge o
28、f 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 bale and adjustthe lever
29、 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.9.15 If using a variable
30、 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 During the test, record the
31、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 the drive motor until th
32、e 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.FIG. 1 Test SchematicG1760329.20 Make surface roughness measurements and pr
33、ofilome-ter traces across the width of the block and the ring as desired.A trace along the long axis of the block, through the wear scar,is also useful to verify the scar depth and shape.9.21 Measure the scar width on the test block in the centerand 1 mm (0.04 in.) away from each edge. These measure
34、-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 width in an area where this is n
35、ot 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 see 9.21, 9.22, and Fig. 4 in Test
36、 Method G 77.10. 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, 0.025 mm (0.250 + 0.000, 0.001in.).
37、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 effects ofNOTEThe outer diameter an
38、d 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 RingG176033material transfer. Keeping this in mind, block mass loss may beinterpreted se
39、mi-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 example,material transfer, plastic deformation, and so forth.10.2 Calculate coeffi
40、cient 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(2)10.3.1 If the ring gains mass during t
41、he 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 from the weight lossmeasurement, but a nota
42、tion 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 unusual event or an overload shutoff of thema
43、chine (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 Parameters:11.2.1.1 Block material,11.2.1.2 Rin
44、g 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 deviation divided by the average; it is exp
45、ressed 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 ring,11.2.3.2 Ring heat treatment, and11.2
46、.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 stated test procedure.12.2 The consistency
47、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.G176034TABLE 1 Block Scar Widths and Volumes for Blocks 6.35-mm Wide Mated Against Rings 34.99 mm in DiameterBlo
48、ck 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 0.03
49、31 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 0.0360 1.77 0.1679 2.47 0.4567 3.17 0.9663 3.88 1.77400.36 0.0014 1.07 0.0371 1.78 0.1708 2.48 0.4622 3.18 0.9755 3.89 1.78780.37 0.0015 1.08 0.0381 1.79 0.1737 2.49 0.4679 3.19 0.9847 3.90 1.80170.38 0.0017 1.09 0.0392 1.80 0.1766 2.50 0.4735 3.20 0.9940 3.91 1.81560.39 0.0018 1.10 0.0403 1.81 0.1796 2.51 0.4792 3.21 1.0034 3.92 182960.40 0.0019 1.11 0.0414
