ASTM G176-03

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.

General Information

• Status: Historical
• Publication Date: 09-Jun-2003
• ICS: 19.060 - Mechanical testing
• ICS: 83.080.01 - Plastics in general
• Technical Committee: G02 - Wear and Erosion
• Drafting Committee: G02.40 - Non-Abrasive Wear

Relations

• Replaced By: ASTM G176-03(2009) - Standard Test Method for Ranking Resistance of Plastics to Sliding Wear using Block-on-Ring Wear Test—Cumulative Wear Method
• Effective Date: 01-May-2009
• Referred By: ASTM G115-10(2018) - Standard Guide for Measuring and Reporting Friction Coefficients
• Effective Date: 10-Jun-2003

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: G 176 – 03
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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope G40 Terminology Relating to Wear and Erosion
G77 Test Method for Ranking Resistance of Materials to
1.1 This test method covers laboratory procedures for de-
Sliding Wear Using a Block-on-Ring Wear Test
termining the resistance of plastics to sliding wear. The test
G117 Guide for Calculating and Reporting Measures of
utilizes a block-on-ring friction and wear testing machine to
Precision Using Data from Interlaboratory Wear or Ero-
rank plastics according to their sliding wear characteristics
sion Tests
against metals or other solids.
1.2 An important attribute of this test is that it is very
3. Terminology
flexible.Anymaterialthatcanbefabricatedinto,orappliedto,
3.1 Definition:
blocks and rings can be tested. Thus, the potential materials
3.1.1 wear—damage to a solid surface, generally involving
combinations are endless. In addition, the test can be run with
progressive loss of material, due to relative motion between
different gaseous atmospheres and elevated temperatures, as
that surface and a contacting substance or substances. G40
desired, to simulate service conditions.
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:
2 will depend on the relative match of test conditions to the
D618 Practice for Conditioning Plastics for Testing
conditions of the service application.
D2714 Test Method for Calibration and Operation of the
3 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
E122 Practice for Calculating Sample Size to Estimate,
sliding wear resistance of plastics, using cumulative volume
With a Specified Tolerable Error, the Average for Charac-
loss.
teristic of a Lot or Process
5.3 The intended use of this test is for coarse screening of
E177 Practice for Use of the Terms Precision and Bias in
4 plastics in terms of their resistance to sliding wear.
ASTM Test Methods
E691 Practice for Conducting an Inter-laboratory Study to
6. Apparatus and Test Specimens
Determine the Precision of a Test Method
6.1 Test Schematic—Aschematic of the block-on-ring wear
testgeometryisshowninFig.1.Inthefigure,thefrictionload
cell is enlarged.
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-
6.2 Test Ring—A typical test ring is shown in Fig. 2. The
Abrasive Wear.
test ring must have an outer diameter of 34.99 6 0.025 mm
Current edition approved June 10, 2003. Published July 2003.
Annual Book of ASTM Standards, Vol 08.01.
Annual Book of ASTM Standards, Vol 05.01.
4 5
Annual Book of ASTM Standards, Vol 14.02. Annual Book of ASTM Standards, Vol 03.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
G176–03
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-
(1.377 6 0.001 in.) with an eccentricity between the inner and
ogy.Scanningelectronmicrographsmaybeused,asdesired,to
outer 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
9.6 Demagnetize the ring and ferrous assembly.
a roughness of 0.152 to 0.305 µm (6 to 12 µin.) rms or center
9.7 Measure the block width and ring diameter to the
line average (CLA), in the direction of motion. However,
nearest 0.025 mm (0.001 in.).
alternate surface conditions may be evaluated in the test, as
9.8 Clean the self-aligning block holder, ring shaft, and
desired. It should be kept in mind that surface condition can
surrounding fixtures with solvent.
have an effect on sliding wear results.
9.9 Put the self-aligning block holder on the block.Apply a
NOTE 1—Acommonly used test ring is a carburized 4620 steel having
thin layer of lubricant to the self-aligning holder. Use of a
a hardness of 60 HRC or higher.
non-migrating product is suggested.
6.3 Test Block—AtestblockisshowninFig.3.Blockwidth
9.10 Place the block in position on the machine and, while
is 6.35 + 0.000, −0.025 mm (0.250 + 0.000, −0.001 in.).
holding the block in position, place the ring on the shaft and
6.4 Optical Device (or equivalent), with metric or English
lock the ring in place, using a method in accordance with the
unit calibration, is also necessary so that scar width can be
requirements of the specific machine design.
measured with a precision of 0.01 mm (0.0004 in.) or equiva-
9.11 Center the block on the ring while placing a light
lent.
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
7. Reagents
edge of the ring and that the mating surfaces are perfectly
7.1 Reagents may include the following: aligned. This is accomplished by making sure the specimen
holder is free during mounting so that the quarter segment can
NOTE 2—Organic cleaners should be used with caution as they may
properly seat itself. Release the pressure on the lever arm.
react with the plastic being tested.
9.12 Place the required weights on the load bale and adjust
7.1.1 Methanol.
the lever arm in accordance with the requirements of the
7.1.2 Eye Glass Cleaner.
specific machine design to provide a load of 44.3 N (10 lbf) at
the block/ring interface. Then remove the load by raising the
8. Preparation and Calibration of Apparatus
weights.
8.1 Run the calibration procedure that is in Test Method
9.13 Set the revolution counter to zero.
D2714 to ensure good mechanical operation of the test
9.14 Gently lower the weights to apply the required load.
equipment.
9.15 If using a variable speed machine, turn on the machine
and slowly increase the power to the drive motor until the ring
9. Procedure
starts to rotate, and record the “static” friction force. Continue
9.1 Condition the test specimens at 23 6 2°C (73.4 6
to increase the rate of rotation to 200 rpm. If using a fixed
3.6°F) and 50 6 5% relative humidity for not less than 40 h
speed machine, simply turn on the machine.
prior to testing in accordance with Procedure A of Practice
9.16 During the test, record the friction force.
D618 for those samples where conditioning is required.
9.17 Stop the test manually or automatically after 240000
9.2 The recommended test conditions are the standard
revolutions (20 h).
laboratory atmosphere of 23 6 2°C (73.4 6 3.6°F) and 50 6
9.18 A final “static” friction force may be measured with a
5% relative humidity.
variablespeedmachine.Leavingonthefullload,wait3min 6
9.3 Clean the ring using a procedure that will remove any
10 s, then turn on the machine and slowly increase the power
scale, oil film, or residue without damaging the surface. The
to the drive motor until the ring starts to rotate, recording the
following procedure is recommended: clean the ring in a
final “static” friction force. Then turn off the motor.
suitable solvent, ultrasonically, if possible; a methanol rinse
maybeusedtoremoveanytracesofsolventresidue.Allowthe 9.19 Remove the block and ring and clean. For metals, use
rings to dry completely. Handle the ring with clean, lint-free a suitable solvent. For plastics, remove loose debris with a dry
cotton gloves from this point on. soft brush.
G176–03
NOTE—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
9.20 Make surface roughness measurements and profilome- shall be declared invalid. For further discussion of measure-
ter traces across the width of the block and the ring as desired. ment problems see 9.21, 9.22, and Fig. 4 inTest MethodG77.
Atrace along the long axis of the block, through the wear scar,
is also useful to verify the scar depth and shape. 10. Calculation
9.21 Measure the scar width on the test block in the center
10.1 Calculation of Block Scar Volume:
and ~1 mm (0.04 in.) away from each edge. These measure-
10.1.1 Block scar volume may be derived from block scar
ments shall be to the nearest 0.01 mm (0.0004 in.). Record the
width by using Table 1 (applicable only when ring diameter is
average of the three readings. Sometimes a lip of plastically
34.99 6 0.025 mm (1.377 6 0.001 in.) and scar length (block
deformed material will extend over the edge of the wear scar.
width) is 6.35 + 0.000, −0.025 mm (0.250 + 0.000, −0.001
Whenmeasuringscarwidth,trytovisuallyignorethismaterial
in.)).
or measure the scar width in an area where this is not a
10.1.2 The preferred method of calculating block scar
problem.
volume is by using the formula shown in Fig. 4. This formula
9.22 Tapered scars indicate improper block alignment dur- may be programmed on a calculator or computer.
ing testing. If the three width measurements on a given scar 10.1.3 Block scar volume is not calculated generally from
have a coefficient of variation of greater than 10%, the test block mass loss because block mass is subject to effects of
G176–03
materialtransfer.Keepingthisinmind,blockmasslossmaybe shutoff at a preset frictional load). If the machine malfunctions
interpreted semi-quantitatively in a comparative evaluation of oratestblockhasataperedscar,thedatashallnotbeused,and
variousmaterialcouples.Iftheblockscarcannotbeaccurately the test shall be rerun.
measured following 9.21, a scar volume should not be calcu- 11.2 Report the following:
lated, but a notation made of the problem, for example, 11.2.1 Test Parameters:
material transfer, plastic deformation, and so forth. 11.2.1.1 Block material,
10.2 Calculate coefficient of friction values from friction 11.2.1.2 Ring material and hardness (whenever applicable),
force values as follows: 11.2.1.3 Ring and block initial surface roughness, and
11.2.1.4 Number of replicates.
F
ƒ 5 (1)
11.2.2 Results—Report the average and the coefficient of
W
variation of the following (the coefficient of variation is the
where:
standard deviation divided by the average; it is expressed as a
ƒ = coefficient of friction,
percent).
F = measured friction force, N (lbf), and
11.2.2.1 Block scar width, mm,
W = applied load, 44.3 N (10 lbf). 3
11.2.2.2 Block scar volume, mm , calculated from scar
10.3 Calculate ring volume loss as follows:
width, and
ringmassloss 11.2.2.3 Ambient conditions, if other than normal labora-
volumeloss 5 (2)
ringdensity
tory conditions.
11.2.3 Reporting Optional:
10.3.1 Iftheringgainsmassduringthetest,thevolumeloss
11.2.3.1 Final surface roughness of block and ring,
is reported as zero with a notation that weight gain occurred.
11.2.3.2 Ring heat treatment, and
Ring mass loss can be affected by transfer of the plastic to the
11.2.3.3 Initial “static” and dynamic coefficients of friction
metal surface. If plastic transfer to the ring is obvious, then a
and final “static” and dynamic coefficients of friction.
ringscarvolumeshouldnotbecalculatedfromtheweightloss
measurement, but a notation should be made that plastic
12. Precision and Bias
transfer occurred. If there are obvious signs of abrasion of the
12.1 The precision and bias of the measurements obtained
ring surface, such as scratches or grooving, this should also be
noted. In this case profilometry may be used to measure with this test procedure will depend upon strict adherence to
the stated test procedure.
material loss.
12.2 The consistency of agreement in repeated tests on the
11. Report
same material will depend upon material consistency, machine
11.1 Report any unusual event or an overload shutoff of the and material interaction, and close observation of the test by a
machine(onsomemachinesitispossibletohaveanautomatic competent machine operator.
G176–03
TABLE 1 Block Scar Widths and Volumes for Blocks 6.35-mm Wide Mated Against Rings 34.99 mm in Diameter
Block Scar Block Scar
Volume Width Volume Width Volume Volume Width Volume Width Volume
Width Width
3 3 3 3 3 3
(mm ) (mm) (mm ) (mm) (mm ) (mm ) (mm) (mm ) (mm) (mm )
(mm) (mm)
0.30 0.0008 1.01 0.0312 1.72 0.1541 2.42 0.4295 3.12 0.9212 3.83 1.7062
0.31 0.0009 1.02 0.0321 1.73 0.1568 2.43 0.4348 3.13 0.9301 3.84 1.7196
0.32 0.0010 1.03 0.0331 1.74 0.1595 2.44 0.4402 3.14 0.9391
...