ASTM G137-97

Standard Test Method for Ranking Resistance of Plastic Materials to Sliding Wear Using a Block-On-Ring Configuration

SCOPE
1.1 This test method covers a laboratory procedure to measure the resistance of plastic materials under dry sliding conditions. The test utilizes a block-on-ring geometry to rank materials according to their sliding wear characteristics under various conditions.  
1.2 The test specimens are small so that they can be molded or cut from fabricated plastic parts. The test may be run at the load, velocity, and temperature which simulate the service condition.  
1.3 Wear test results are reported as specific wear rates calculated from volume loss, sliding distance, and load. Materials with superior wear resistance have lower specific wear rates.  
1.4 This test method allows the use of both single- and multi-station apparatus to determine the specific wear rates.  
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-Apr-1997
• ICS: 19.060 - Mechanical testing
• ICS: 83.140.01 - Rubber and plastics products in general
• Technical Committee: G02 - Wear and Erosion
• Drafting Committee: G02.40 - Non-Abrasive Wear

Relations

• Replaced By: ASTM G137-97(2003) - Standard Test Method for Ranking Resistance of Plastic Materials to Sliding Wear Using a Block-On-Ring Configuration
• Effective Date: 10-Jun-2003
• Referred By: ASTM G115-10(2018) - Standard Guide for Measuring and Reporting Friction Coefficients
• Effective Date: 10-Apr-1997

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: G 137 – 97
Standard Test Method for
Ranking Resistance of Plastic Materials to Sliding Wear
Using a Block-On-Ring Configuration
This standard is issued under the fixed designation G 137; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope G 77 Test Method for Ranking Resistance of Materials to
Sliding Wear Using Block-on-Ring Wear Test
1.1 This test method covers a laboratory procedure to
G 117 Guide for Calculating and Reporting Measures of
measure the resistance of plastic materials under dry sliding
Precision Using Data from Interlaboratory Wear or Ero-
conditions. The test utilizes a block-on-ring geometry to rank
sion Tests
materials according to their sliding wear characteristics under
various conditions.
3. Terminology
1.2 The test specimens are small so that they can be molded
3.1 Definitions:
or cut from fabricated plastic parts. The test may be run at the
3.1.1 wear—damage to a solid surface, generally involving
load, velocity, and temperature which simulate the service
progressive loss of material, due to relative motion between
condition.
that surface and a contacting substance or substances.
1.3 Wear test results are reported as specific wear rates
3.1.2 Additional definitions relating to wear are found in
calculated from volume loss, sliding distance, and load. Mate-
Terminology G 40.
rials with superior wear resistance have lower specific wear
3.2 Definitions of Terms Specific to This Standard:
rates.
3.2.1 specific wear rate—the volume loss per unit sliding
1.4 This test method allows the use of both single- and
distance, divided by the load. It can be calculated as the volume
multi-station apparatus to determine the specific wear rates.
loss per unit time, divided by the load and the sliding velocity.
1.5 This standard does not purport to address all of the
3.2.2 steady state specific wear rate—the specific wear rate
safety concerns, if any, associated with its use. It is the
that is established during that part of the test when the specific
responsibility of the user of this standard to establish appro-
wear rate remains substantially constant (the specific wear rate
priate safety and health practices and determine the applica-
versus sliding distance curve flattens out considerably with less
bility of regulatory limitations prior to use.
than 30 % difference between the specific wear rates) during a
2. Referenced Documents minimum of three time intervals spanning a total time duration
of at least 18 h, with ideally no single interval exceeding 8 h.
2.1 ASTM Standards:
However, one time interval during the steady state can be as
D 618 Practice for Conditioning Plastics for Testing
long as 16 h.
D 3702 Test Method for Wear Rate of Materials in Self-
Lubricated Rubbing Contact Using a Thrust Washer Test-
4. Summary of Test Method
ing Machine
4.1 A plastic block of known dimensions is brought into
E 122 Practice for Choice of Sample Size to Estimate a
4 contact with a counterface ring (usually metal) under con-
Measure of Quality for a Lot or Process
trolled conditions of contact pressure and relative velocity. This
E 177 Practice for Use of the Terms Precision and Bias in
4 is achieved using a block-on-ring configuration as illustrated in
ASTM Test Methods
5 Fig. 1. Periodic weighing of the polymer block results in a
G 40 Terminology Relating to Wear and Erosion
number of mass-time data points where the time relates to the
time of sliding. The test is continued until the steady state wear
This test method is under the jurisdiction of ASTM Committee G-2 on Wear rate is established. Mass loss measurements made after the
and Erosion and is the direct responsibility of Subcommittee G02.40 on Non-
steady state is established are used to determine the steady state
Abrasive Wear.
specific wear rate, which is the volume loss per unit sliding
Current edition approved Apr. 10, 1997. Published November 1997. Originally
distance per unit load. The frictional torque may also be
published as G 137 – 95. Last previous edition G 137 – 95.
Annual Book of ASTM Standards, Vol 08.01.
measured during the steady state using a load cell. These data
Annual Book of ASTM Standards, Vol 05.02.
can be used to evaluate the coefficiency of friction for the test
Annual Book of ASTM Standards, Vol 14.02.
5 combination.
Annual Book of ASTM Standards, Vol 03.02.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
G137–97
FIG. 1 Single Station Block-on-Ring Arrangement
NOTE 1—Another test method that utilizes a block-on-ring test configu-
reposition the specimen after weighing as before, and a
ration for the evaluation of plastics is Test Method G 77.
counterface ring with acceptable eccentricity. All other design
elements can be varied according to the user preference.
5. Significance and Use
6.1.1 Bearings recommended for counterface drive shafts
5.1 The specific wear rates determined by this test method
are industrial-grade tapered roller bearings.
can be used as a guide in ranking the wear resistance of plastic
6.1.2 Required centerline alignment limits of the counter-
materials. The specific wear rate is not a material property and
face drive shafts are 60.41 mm (60.016 in.) from the center of
will therefore differ with test conditions and test geometries.
a counterface ring. Allowable eccentricity of the counterface
The significance of this test will depend on the relative
ring is no greater than 60.06 mm (60.002 in.).
similarity to the actual service conditions.
6.1.3 Bearings recommended for the linear ball grooved
5.2 This test method seeks only to describe the general test
bushing bearing are industrial-grade linear bearings.
procedure and the procedure for calculating and reporting data.
6.2 Counterface Ring—The recommended dimensions for
NOTE 2—This test configuration allows steady state specific wear rates the counterface ring are 100 + 0.05, − 0.00-mm diameter and
to be achieved very quickly through the use of high loads and speeds. The
15.88 + 0.30, − 0.13-mm width. Often a hardened tool steel
thrust washer configuration described in Test Method D 3702 does not
ring with a hardness of 50 to 60 HRC and a surface roughness
allow the use of such high speeds and loads because of possible
of 0.102 to 0.203 μm (4 to 8 μin.) R in the direction of sliding
a
overheating (which may cause degradation or melting, or both) of the
is used for the general evaluation of plastics. The requirement
specimen. Despite the differences in testing configurations, a good
for the ring material is that it should not wear appreciably or
correlation in the ranking of wear resistance is achieved between the two
change dimensions during the course of the test. Therefore,
tests (Table X2.1).
other materials and surface conditions may also be used. It
6. Apparatus and Materials
should be noted that test results will be influenced by the
6.1 Test Setup—An example of the basic test configuration choice of ring material and surface roughness.
and part names are shown in Fig. 1. The recommended 6.3 Test Block—The recommended dimensions of the test
dimensions of the test apparatus are shown in Fig. 2. The block are 6.35 + 0.00, − 0.03-mm (0.250 + 0.000, − 0.001-in.)
figures shown in this test method represent one example of a width, 6.00 + 0.00, − 0.03-mm (0.236 + 0.000, − 0.001-in.)
block-on-ring test apparatus. The mandatory elements are: the depth, and 12.70 6 0.2-mm height. For materials where
capability to change load and sliding speed, the ability to surface condition is not a parameter under study, a ground
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
G137–97
NOTE 1—All dimensions are given in millimetres.
FIG. 2 Recommended Dimensions of Block-on-Ring Apparatus
surface with the grinding marks running parallel to the depth 8. Preparation and Calibration of Apparatus
direction of the block and a roughness of 0.102 to 0.203 μm (4
8.1 Perform calibration of torque transducers by applying
to 8 μin.) R in the direction of motion is recommended.
a
NIST traceable dead weight standards and using a reference
However, other surface conditions may be evaluated as de-
load cell.
sired.
8.2 Perform calibration of tachometer by comparison to a
6.4 Test Parameters:
hand-held tachometer which has been calibrated with NIST
6.4.1 The recommended range for the normal load is from
traceable standards.
20 to 40 N.
6.4.2 The recommended range for the velocity is from 0.5 to
9. Conditioning
1 m/s.
6.5 Apparatus:
9.1 Conditioning—Condition the test specimens at 23 6
6.5.1 Analytical Balance, capable of measuring to the near-
2°C (73.4 6 3.6°F) and 50 6 5 % relative humidity for not less
est 0.01 mg.
than 40 h prior to testing in accordance with Procedure A of
Practice D 618 for those samples where conditioning is re-
7. Reagents
quired.
7.1 Suitable cleaning procedures should be used to clean
9.2 Test Conditions—The recommended conditions are the
counterface ring and test block. Reagents proven suitable for
standard laboratory atmosphere of 23 6 2°C (73.4 6 3.6°F)
some materials are:
and 50 6 5 % relative humidity.
7.1.1 Acetone, for steel rings, and
7.1.2 Methanol, for test block surface and specimen holder.
7.2 Both solvents are flammable and toxic. Refer to the
relevant Material Safety Data Sheet (MSDS) before using the 6
The interlaboratory tests were conducted using the torque transducers manu-
solvents. factured by Key Transducers, Inc., Sterling Heights, MI.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
G137–97
10. Procedure 10.9 Frictional torque values produced by the machine itself
(should not be more than 60.05 Nm) should be zeroed as
10.1 Clean the counterface ring using mild soap and water
follows:
so as to remove bulk dirt and corrosion-inhibiting oil. After-
10.9.1 The block-on-ring tester is turned on without any
wards, clean the counterface ring in an ultrasonic acetone bath
load being applied to the specimen. This gives a stable torque
for 2 h (43 kHz 95 W) to remove the remaining contaminants.
reading which should be zeroed. After zero marker is obtained,
Allow the ring to dry completely. Handle the ring from this
load may be applied to run the test.
point on with lint-free cotton gloves.
10.10 Bring the lever arm angle adjusting rod gently into
10.2 Mount the counterface ring on the drive shaft and
contact with the specimen load shaft to apply the load.
secure with a counterface retaining nut (Fig. 1).
10.11 Start the motor and adjust to a desired speed. The
10.3 Clean the test block and specimen holder with metha-
speed should preferably not exceed 1 m/s.
nol. Handle the test block and the specimen holder with
10.11.1 Frictional torque values may be recorded so that an
lint-free cotton gloves from this point.
average value for the test period may be obtained. Values for
10.4 Measure the width and the depth of the test block to
the frictional force can be obtained from these measurements
ensure that the surface dimensions fall within the specifica-
by dividing the frictional torque by an appropriate moment
tions.
arm.
10.5 Mount the test block into the specimen holder and
10.12 The test should be interrupted a minimum of six times
tighten so that the test block does not move within the
to determine mass loss as a function of time, though more may
specimen holder (Fig. 3).
be required to ensure that steady state is established. The
10.6 Weigh the test block and specimen holder to the
intervals need not be uniform. Shorter intervals should be used
nearest 0.01 mg.
during the initial portion of the test and longer intervals during
10.7 Position the specimen holder with the test block under
the latter portion of the test. The test should be continued until
the counterface ring. Repositioning is possible with the use of
three or more of the intervals occur in the steady state range.
a guide that the specimen load shaft slides on and an alignment
10.12.1 Halt the speed controlling motor for weight mea-
screw which secures the specimen holder to the specimen load
surements.
shaft. The linear ball grooved bushing bearing prevents the
10.12.2 Remove the load from the test block by removing
specimen load shaft from rotating.
the lever arm angle adjusting rod from the specimen load shaft.
10.8 Apply the required load. Yokes 1 and 2, and Nuts 1 and
10.12.3 Remove the specimen holder with the test block
2 in Fig. 1 are of equal weight and will not figure into
from the specimen load shaft.
calculations. The weight of the weight hanger will be included
10.12.4 Use compressed air to blow off the worn particles
in the total weight needed. The weight of specimen, specimen
from the test block and from within the specimen holder.
holder, specimen load shaft, and lever arm angle adjusting rod
10.12.5 Weigh the specimen holder with the test block on a
will have to be countered to equal the desired force. To ensure
balance to the nearest 0.01 mg.
that the proper load has been applied, a small load cell can be
10.12.6 Reload the specimen holder with the test block
mounted between the specimen and the counterface ring with
following the procedure in 10.7-10.11.
the load being applied. The lever arm should be maintained
horizontally by adjusting the height of the lever arm angle
11. Calculation
adjusting rod. The required load can be applied by other
11.1 Calculation of Specific Wear Rate:
mechanisms.
11.1.1 Periodic weighing of the specimen holder and the test
block results in a number of mass-time data points where the
time relates to the time of sliding.
11.1.2 The specific wear rate for each interval can be
calculated from (Eq 1):
1 Dm
W 5 · (1)
s
F vr Dt
N
where:
3 2
W = specific wear rate, mm /N·m, dimensions, (L /F),
s
F = applied normal force, N,
N
v = velocity, m/s,
r = density, kg/mm ,
Dm = mass loss, kg, and
Dt = time interval, s.
11.1.3 The specific wear rate reported is the average value
within the steady state region.
11.2 Calculation of Coeffıcient of Friction:
11.2.1 The dynamic coefficient of f
...