ASTM G176-03(2009)
(Test Method)Standard Test Method for Ranking Resistance of Plastics to Sliding Wear using Block-on-Ring Wear Test—Cumulative Wear Method
Standard Test Method for Ranking Resistance of Plastics to Sliding Wear using Block-on-Ring Wear Test—Cumulative Wear Method
SIGNIFICANCE AND USE
The significance of this test method in any overall measurement program directed toward a service application will depend on the relative match of test conditions to the conditions of the service application.
This test method prescribes the test procedure and method of calculating and reporting data for determining the sliding wear resistance of plastics, using cumulative volume loss.
The intended use of this test is for coarse screening of plastics in terms of their resistance to sliding wear.
SCOPE
1.1 This test method covers laboratory procedures for determining the resistance of plastics to sliding wear. The test utilizes a block-on-ring friction and wear testing machine to rank plastics according to their sliding wear characteristics against metals or other solids.
1.2 An important attribute of this test is that it is very flexible. Any material that can be fabricated into, or applied to, blocks and rings can be tested. Thus, the potential materials combinations are endless. In addition, the test can be run with different gaseous atmospheres and elevated temperatures, as desired, to simulate service conditions.
1.3 Wear test results are reported as the volume loss in cubic millimetres for the block and ring. Materials of higher wear resistance will have lower volume loss.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: G176 − 03 (Reapproved 2009)
Standard Test Method for
Ranking Resistance of Plastics to Sliding Wear Using
Block-on-Ring Wear Test—Cumulative Wear Method
This standard is issued under the fixed designation G176; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E177Practice for Use of the Terms Precision and Bias in
ASTM Test Methods
1.1 This test method covers laboratory procedures for de-
E691Practice for Conducting an Interlaboratory Study to
termining the resistance of plastics to sliding wear. The test
Determine the Precision of a Test Method
utilizes a block-on-ring friction and wear testing machine to
G40Terminology Relating to Wear and Erosion
rank plastics according to their sliding wear characteristics
G77Test Method for Ranking Resistance of Materials to
against metals or other solids.
Sliding Wear Using Block-on-Ring Wear Test
1.2 An important attribute of this test is that it is very
flexible.Anymaterialthatcanbefabricatedinto,orappliedto, 3. Terminology
blocks and rings can be tested. Thus, the potential materials
3.1 Definitions:
combinations are endless. In addition, the test can be run with
3.1.1 wear—damage to a solid surface, generally involving
different gaseous atmospheres and elevated temperatures, as
progressive loss of material, due to relative motion between
desired, to simulate service conditions.
that surface and a contacting substance or substances. G40
1.3 Weartestresultsarereportedasthevolumelossincubic
4. Summary of Test Method
millimetres for the block and ring. Materials of higher wear
4.1 A test plastic block is loaded against a metal test ring
resistance will have lower volume loss.
that rotates at a given speed for a given number of revolutions.
1.4 The values stated in SI units are to be regarded as the
Blockscarvolumeiscalculatedfromtheblockscarwidth.The
standard. The values given in parentheses are for information
friction force required to keep the block in place may be
only.
continuously measured during the test with a load cell. When
1.5 This standard does not purport to address all of the
this is done, the friction force data are combined with normal
safety concerns, if any, associated with its use. It is the
force data to obtain values for the coefficient of friction and
responsibility of the user of this standard to establish appro-
reported.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 5. Significance and Use
5.1 The significance of this test method in any overall
2. Referenced Documents
measurement program directed toward a service application
2.1 ASTM Standards:
will depend on the relative match of test conditions to the
D618Practice for Conditioning Plastics for Testing
conditions of the service application.
D2714Test Method for Calibration and Operation of the
5.2 This test method prescribes the test procedure and
Falex Block-on-Ring Friction and Wear Testing Machine
method of calculating and reporting data for determining the
E122PracticeforCalculatingSampleSizetoEstimate,With
sliding wear resistance of plastics, using cumulative volume
Specified Precision, the Average for a Characteristic of a
loss.
Lot or Process
5.3 The intended use of this test is for coarse screening of
plastics in terms of their resistance to sliding wear.
This test method is under the jurisdiction of ASTM Committee G02 on Wear
and Erosion and is the direct responsibility of Subcommittee G02.40 on Non-
6. Apparatus and Test Specimens
Abrasive Wear.
Current edition approved May 1, 2009. Published May 2009. Originally
6.1 Test Schematic—Aschematic of the block-on-ring wear
approved in 2003. Last previous edition approved in 2003 as G176–03. DOI:
testgeometryisshowninFig.1.Inthefigure,thefrictionload
10.1520/G0176-03R09.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or cell is enlarged.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6.2 Test Ring—AtypicaltestringisshowninFig.2.Thetest
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. ring must have an outer diameter of 34.99 6 0.025 mm (1.377
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G176 − 03 (2009)
9.4 For the plastic block, the following cleaning procedure
isrecommended:Cleantheplasticblockwithmethanol.Allow
the blocks to dry completely.After cleaning, handle the block
with clean, lint-free cotton gloves. Other procedures may be
used provided they do not affect the plastic. If an application
understudyusesaplasticinthemoldedcondition,itisadvised
to test a block with the test surface in the molded condition.
The wear of a molded surface may be different from the wear
of a machined surface.
FIG. 1 Test Schematic
9.5 Make surface texture and surface roughness measure-
ments across the width of the ring, as necessary. Note that a
surface profile does not completely describe a surface topol-
6 0.001 in.) with an eccentricity between the inner and outer
ogy.Scanningelectronmicrographsmaybeused,asdesired,to
surfaces of no greater than 0.00125 mm (0.0005 in.). For
augment the description of the wear surfaces. Clean the ring
couples where surface condition is not under study, it is
again, if necessary, as in 9.3.
recommended that the outer diameter be a ground surface with
a roughness of 0.152 to 0.305 µm (6 to 12 µin.) rms or center
9.6 Demagnetize the ring and ferrous assembly.
line average (CLA), in the direction of motion. However,
9.7 Measure the block width and ring diameter to the
alternate surface conditions may be evaluated in the test, as
nearest 0.025 mm (0.001 in.).
desired. It should be kept in mind that surface condition can
have an effect on sliding wear results. 9.8 Clean the self-aligning block holder, ring shaft, and
NOTE 1—Acommonly used test ring is a carburized 4620 steel having
surrounding fixtures with solvent.
a hardness of 60 HRC or higher.
9.9 Put the self-aligning block holder on the block.Apply a
6.3 Test Block—AtestblockisshowninFig.3.Blockwidth
thin layer of lubricant to the self-aligning holder. Use of a
is 6.35 + 0.000, −0.025 mm (0.250 + 0.000, −0.001 in.).
non-migrating product is suggested.
6.4 Optical Device (or equivalent), with metric or English
9.10 Place the block in position on the machine and, while
unit calibration, is also necessary so that scar width can be
holding the block in position, place the ring on the shaft and
measured with a precision of 0.01 mm (0.0004 in.) or equiva-
lock the ring in place, using a method in accordance with the
lent.
requirements of the specific machine design.
7. Reagents
9.11 Center the block on the ring while placing a light
7.1 Reagents may include the following:
manual pressure on the lever arm to bring the block and ring
into contact. Be sure the edge of the block is parallel to the
NOTE 2—Organic cleaners should be used with caution as they may
edge of the ring and that the mating surfaces are perfectly
react with the plastic being tested.
aligned. This is accomplished by making sure the specimen
7.1.1 Methanol.
holder is free during mounting so that the quarter segment can
7.1.2 Eye Glass Cleaner.
properly seat itself. Release the pressure on the lever arm.
8. Preparation and Calibration of Apparatus
9.12 Place the required weights on the load bale and adjust
the lever arm in accordance with the requirements of the
8.1 Run the calibration procedure that is in Test Method
specific machine design to provide a load of 44.3 N (10 lbf) at
D2714 to ensure good mechanical operation of the test
the block/ring interface. Then remove the load by raising the
equipment.
weights.
9. Procedure
9.13 Set the revolution counter to zero.
9.1 Condition the test specimens at 23 6 2°C (73.4 6
9.14 Gently lower the weights to apply the required load.
3.6°F) and 50 6 5% relative humidity for not less than 40 h
prior to testing in accordance with Procedure A of Practice
9.15 If using a variable speed machine, turn on the machine
D618 for those samples where conditioning is required.
and slowly increase the power to the drive motor until the ring
starts to rotate, and record the “static” friction force. Continue
9.2 The recommended test conditions are the standard
to increase the rate of rotation to 200 rpm. If using a fixed
laboratory atmosphere of 23 6 2°C (73.4 6 3.6°F) and 50 6
speed machine, simply turn on the machine.
5% relative humidity.
9.3 Clean the ring using a procedure that will remove any 9.16 During the test, record the friction force.
scale, oil film, or residue without damaging the surface. The
9.17 Stop the test manually or automatically after 240000
following procedure is recommended: clean the ring in a
revolutions (20 h).
suitable solvent, ultrasonically, if possible; a methanol rinse
maybeusedtoremoveanytracesofsolventresidue.Allowthe 9.18 Afinal “static” friction force may be measured with a
rings to dry completely. Handle the ring with clean, lint-free variablespeedmachine.Leavingonthefullload,wait3min 6
cotton gloves from this point on. 10 s, then turn on the machine and slowly increase the power
G176 − 03 (2009)
NOTE 1—The outer diameter and concentricity with the inner diameter are the only critical parameters. The inner diameter is optional depending on
machine design. The inside diameter taper shown fits a number of standard machines.
FIG. 2 Test Ring
to the drive motor until the ring starts to rotate, recording the 9.22 Tapered scars indicate improper block alignment dur-
final “static” friction force. Then turn off the motor. ing testing. If the three width measurements on a given scar
have a coefficient of variation of greater than 10%, the test
9.19 Remove the block and ring and clean. For metals, use
shall be declared invalid. For further discussion of measure-
a suitable solvent. For plastics, remove loose debris with a dry
ment problems see 9.21, 9.22, and Fig. 4 in Test Method G77.
soft brush.
9.20 Make surface roughness measurements and profilome- 10. Calculation
ter traces across the width of the block and the ring as desired.
10.1 Calculation of Block Scar Volume:
Atracealongthelongaxisoftheblock,throughthewearscar,
10.1.1 Block scar volume may be derived from block scar
is also useful to verify the scar depth and shape.
width by using Table 1 (applicable only when ring diameter is
9.21 Measure the scar width on the test block in the center 34.99 6 0.025 mm (1.377 6 0.001 in.) and scar length (block
and ~1 mm (0.04 in.) away from each edge. These measure- width) is 6.35 + 0.000, −0.025 mm (0.250 + 0.000, −0.001
ments shall be to the nearest 0.01 mm (0.0004 in.). Record the in.)).
average of the three readings. Sometimes a lip of plastically 10.1.2 The preferred method of calculating block scar
deformed material will extend over the edge of the wear scar. volume is by using the formula shown in Fig. 4. This formula
Whenmeasuringscarwidth,trytovisuallyignorethismaterial may be programmed on a calculator or computer.
or measure the scar width in an area where this is not a 10.1.3 Block scar volume is not calculated generally from
problem. block mass loss because block mass is subject to effects of
G176 − 03 (2009)
FIG. 3 Test Block
materialtransfer.Keepingthisinmind,blockmasslossmaybe 11.2.1.1 Block material,
interpreted semi-quantitatively in a comparative evaluation of 11.2.1.2 Ring material and hardness (whenever applicable),
variousmaterialcouples.Iftheblockscarcannotbeaccurately 11.2.1.3 Ring and block initial surface roughness, and
measured following 9.21, a scar volume should not be 11.2.1.4 Number of replicates.
calculated, but a notation made of the problem, for example, 11.2.2 Results—Report the average and the coefficient of
material transfer, plastic deformation, and so forth. variation of the following (the coefficient of variation is the
standard deviation divided by the average; it is expressed as a
10.2 Calculate coefficient of friction values from friction
percent).
force values as follows:
11.2.2.1 Block scar width, mm,
F 3
11.2.2.2 Block scar volume, mm , calculated from scar
ƒ 5 (1)
W
width, and
11.2.2.3 Ambient conditions, if other than normal labora-
where:
tory conditions.
ƒ = coefficient of friction,
11.2.3 Reporting Optional:
F = measured friction force, N (lbf), and
11.2.3.1 Final surface roughness of block and ring,
W = applied load, 44.3 N (10 lbf).
11.2.3.2 Ring heat treatment, and
10.3 Calculate ring volume loss as follows:
11.2.3.3 Initial “static” and dynamic coefficients of friction
ringmassloss
and final “static” and dynamic coefficients of friction.
volumeloss 5 (2)
ringdensity
12. Precision and Bias
10.3.1 Iftheringgainsmassduringthetest,thevolumeloss
12.1 The precision and bias of the measurements obtained
is reported as zero with a notation that weight gain occurred.
with this test procedure will depend upon strict adherence to
Ring mass loss can be affected by transfer of the plastic to the
the stated test procedure.
metal surface. If plastic transfer to the ring is obvious, then a
ringscarvolumeshouldnotbecalculatedfromtheweightloss
12.2 The consistency of agreement in repeated tests on the
measurement, but a notation should be made that plastic
same material will depend upon material consistency, machine
transfer occurred. If there are obvious signs of abrasion of the
and material interaction, and close observation of the test by a
ring surface, such as scratches or grooving, this should also be
competent machine operator.
noted. In this case profilometry may be used to measure
12.3 Precision—In interlaboratory tests the coefficient of
material loss.
variation between laboratories (reproducibility) and the coef-
ficient of variation within a laboratory (repeatability) are
11. Report
similar but vary with the material. Coefficients were found to
11.1 Report any unusual event or an overload shutoff of the
range from less than 10% up to 100% with a mean value of
machine(onsomemachinesitispossibletohaveanautomatic
approximately 25%. Tables X1.1 and X1.2 show the coeffi-
shutoff at a preset frictional load). If the machine malfunctions
cients of variation, which were obtained in the interlaboratory
oratestblockhasataperedscar,thedatashallnotbeused,and
tests with several materials.
the test shall be rerun.
12.3.1 In order to achieve a high confidence level in
11.2 Report the following: evaluating tes
...
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