ASTM G133-95(2002)e1
(Test Method)Standard Test Method for Linearly Reciprocating Ball-on-Flat Sliding Wear
Standard Test Method for Linearly Reciprocating Ball-on-Flat Sliding Wear
SCOPE
1.1 This test method describes laboratory procedures for determining the sliding wear of ceramics, metals, and other candidate wear-resistant materials using a linear, reciprocating ball-on-flat plane geometry. The direction of the relative motion between sliding surfaces reverses in a periodic fashion such that the sliding occurs back and forth and in a straight line. The principal quantities of interest are the wear volumes of the contacting ball and flat specimen materials; however, the coefficient of kinetic friction may also be measured using the method described. This test method encompasses both unlubricated and lubricated testing procedures. The scope of this test method does not include testing in corrosive or chemically aggressive environments.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 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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e1
Designation: G 133 – 95 (Reapproved 2002)
Standard Test Method for
Linearly Reciprocating Ball-on-Flat Sliding Wear
This standard is issued under the fixed designation G 133; 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.
e NOTE—The final sentence in Footnote 4 was removed editorially July 2002.
1. Scope G 118 Guide for Recommended Data Format of Sliding
Wear Data Suitable for Databases
1.1 This test method describes laboratory procedures for
determining the sliding wear of ceramics, metals, and other
3. Terminology
candidate wear-resistant materials using a linear, reciprocating
3.1 Definitions—Definitions used in this test method are
ball-on-flat plane geometry. The direction of the relative
given in Terminology G 40. The following definitions of
motion between sliding surfaces reverses in a periodic fashion
important terms used in this test method are cited from
such that the sliding occurs back and forth and in a straight
Terminology G 40.
line. The principal quantities of interest are the wear volumes
3.1.1 friction force—the resisting force tangential to the
of the contacting ball and flat specimen materials; however, the
interface between two bodies when, under the action of an
coefficient of kinetic friction may also be measured using the
external force, one body moves or tends to move relative to the
method described. This test method encompasses both unlu-
other.
bricated and lubricated testing procedures. The scope of this
3.1.2 Hertzian contact pressure—the magnitude of the pres-
test method does not include testing in corrosive or chemically
sure at any specified location in a Hertzian contact area, as
aggressive environments.
calculated from Hertz’s equations of elastic deformation.
1.2 The values stated in SI units are to be regarded as the
3.1.3 wear—damage to a solid surface, generally involving
standard. The values given in parentheses are for information
the progressive loss of material, due to relative motion between
only.
that surface and a contacting surface or surfaces.
1.3 This standard does not purport to address all of the
3.1.4 wear rate—the rate of material removal or dimen-
safety concerns, if any, associated with its use. It is the
sional change due to wear per unit of exposure parameter, for
responsibility of the user of this standard to establish appro-
example, quantity removed (mass, volume, thickness) in unit
priate safety and health practices and determine the applica-
distance of sliding or unit time.
bility of regulatory limitations prior to use.
4. Summary of Test Method
2. Referenced Documents
4.1 This test method involves two specimens—a flat speci-
2.1 ASTM Standards:
2 men and a spherically ended specimen (herein called the “ball”
E 112 Test Methods for Determining Average Grain Size
specimen) which slides against the flat specimen. These
E 1181 Test Methods for Characterizing Duplex Grain
2 specimens move relative to one another in a linear, back and
Sizes
3 forth sliding motion, under a prescribed set of conditions.
G 40 Terminology Relating to Erosion and Wear
4.2 In this test method, the load is applied vertically
G 99 Test Method for Wear Testing with a Pin-on-Disk
3 downward through the ball specimen against the horizontally
Apparatus
mounted flat specimen. The normal load, stroke length, fre-
G 115 Guide for Measuring and Reporting Friction Coeffi-
3 quency and type of oscillation, test temperature, lubricant (if
cients
any), test duration, and atmospheric environment (including
G 117 Guide for Calculating and Reporting Measures of
relative humidity range) are selected from one of two proce-
Precision Using Data from Interlaboratory Wear or Ero-
dures.
sion Tests
4.3 Since this test method involves reciprocating sliding
where changes in the sliding velocity and direction of motion
This test method is under the jurisdiction of ASTM Committee G02 on Wear
occur during the test, constant velocity conditions are not
and Erosion and is the direct responsibility of Subcommittee G02.40 on Non-
maintained. The manner in which the velocity varies with time
Abrasive Wear.
is determined by the design of the mechanism which drives the
Current edition approved Oct. 10, 1995. Published December 1995.
ball or flat specimen back and forth.
Annual Book of ASTM Standards, Vol 03.01.
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.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
G 133
FIG. 1 Reciprocating Test—Schematic Diagram
4.4 Dimensional changes for both ball and flat specimens without lubricant. The tangential force can be measured
are used to calculate wear volumes and wear rates. continuously during oscillating contact and used to obtain
4.5 Friction forces are measured during the test and may be friction coefficient data.
used to assess changes in the contact conditions or the kinetic 6.2 Specimen Drive—A drive train, capable of providing
friction coefficient as a function of time. smooth, reciprocating motion to the ball and overcoming the
frictional resistance of the specimens at maximum load, is
5. Significance and Use
required. For example, a Scotch yoke drive mechanism can
5.1 This test method is designed to simulate the geometry
provide a smooth, sinusoidal velocity profile for the ball
and motions that are experienced in many types of rubbing specimen relative to the flat specimen without the need for the
components whose normal operation results in periodic rever-
motor to stop and reverse direction periodically. Stepper-type
sals in the direction of relative sliding. The wear resulting from motors may also be used provided that the motion is smooth
this mode of movement may differ from that experienced by
and uniform.
the same materials sliding continuously in only one direction 6.3 Ball and Ball Specimen Holder—The ball specimen
(unidirectional sliding) even for comparable durations of
may be a fixed bearing ball or any spherically tipped specimen
contact. Test loads and speeds are to be determined by the as long as the sliding contact is equivalent to a ball on a flat
severity of the proposed application or purpose of the testing. plane. If a bearing ball is used, it shall be clamped tightly
Either of two sets of testing conditions (designated Procedures enough to prevent slippage during the test. The ball holder
A and B) may be used. should be rigid enough so that the periodic reversal in the
sliding direction does not result in tilting or other misalignment
6. Apparatus
of the contact.
6.1 General Description—Fig. 1 shows the arrangement for
6.4 Flat Specimen Holder—The flat specimen is secured to
the reciprocating ball-on-flat wear test available on a commer- the base of the machine to prevent slippage or buckling during
cial machine. The ball is rigidly mounted and has a spherical
the test. A variety of shapes and configurations for the flat
tip which moves back and forth across the surface of a polished specimen are possible. The primary criterion is that the coupon
flat specimen. Use of a spherical tip alleviates the alignment
present a flat, horizontal surface to the ball specimen.
problems associated with flat-ended balls sliding on flat sur- 6.5 Instrumentation:
faces. Alternate configurations in which the flat moves and the
6.5.1 Friction Force—A tension-compression load cell or
ball specimen is fixed may be used. A provision is made for similar force-sensing device may be used to measure the
applying a uniform normal force (load) to the contact between
the ball and the flat. Temperature measurement and control
Machines of this type are described in A Catalogue of Friction and Wear
capability is provided to heat and monitor the flat specimen
Devices, American Society of Lubrication Engineers (now STLE) 838 Busse
which may either be immersed in a lubricant bath or tested Highway, Park Ridge, IL, 1973, pp. 50–72.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
G 133
friction forces generated during sliding. Calibration of the shall be kept constant within a maximum deviation of 62.0 %
friction force (see section 7.1.3) in both forward and reverse of the test load. For example, permitted static error of a 25.0-N
sliding directions is required. Since the direction of the friction normal force would be 60.5 N. During oscillating tests, the
force changes rapidly during the test, traditional strip-chart- normal force may vary slightly about the mean value due to the
type recorders may be too slow to follow these changes at high dynamics of the machine. This variation is to be expected.
frequencies of reciprocation. A commercial version of this 7.1.2 Motion Drive—The oscillating frequency of the mov-
machine is available with a signal conditioner to rectify, and ing specimen shall be checked periodically against the drive
output the root-mean-square friction force to a strip-chart- motor setting to ensure that the rate of oscillation is known.
recorder or to a computerized data acquisition system. The
NOTE 1—Caution: Due to inertial effects, differences in the loading
method of sensing and recording friction force during the test
and fixturing method become more significant as the oscillating frequency
shall be described in the testing report.
of the test is increased, and harmonic frequencies characteristic of the test
6.5.2 Test Duration—In this test method, test duration is
machine must be avoided when selecting the oscillating frequency.
specified in seconds. To compute the sliding distance in metres
7.1.3 Friction Force Sensor—The friction force sensor shall
or number of cycles, use the following:
be calibrated periodically in both directions of load application.
X 5 0.002 3 t 3 f 3 L (1)
Depending on the machine, a fixture which applies a calibrat-
ing load in line with the normal point of contact between the
or
ball and flat should be used.
N 5 t 3 f (2)
8. Procedure
where:
8.1 Specimen Preparation—The ball specimen and flat
X = total sliding distance of the ball, m,
N = number of cycles in the test,
specimen shall be used either in a polished condition, or in a
t = test time, s,
specified condition consistent with the application of interest.
f = oscillating frequency, Hz (cycles/s), and
In a polished condition, the surface should be as free as
L = length of stroke, mm.
possible from preparation artifacts such as grinding-induced
A cycle is defined as two stroke lengths (up and back).
cracks, gross grinding marks, and grain pull-out. Surface
Electronic timers can be used to terminate the test. If a
roughnesses of 0.02 to 0.05-μm R (arithmetic roughness) are
a
cycle-counter is available, this may be used instead of the
typical.
timer, in which case Eq 2 will be used.
8.2 Clean the specimens using the following procedure:
6.5.3 Humidity—The wear and friction of many materials is
8.2.1 Wash with a mild liquid laboratory glassware cleaner,
significantly affected by the moisture in the air. It is therefore
8.2.2 Hot air dry,
required that the relative humidity (to an accuracy of 63%)be
8.2.3 Ultrasonically clean in acetone (2 min),
measured before and during the test. Humidity can vary with
8.2.4 Hot air dry,
air flow and in different parts of the same room, so the
8.2.5 Ultrasonically clean in methanol (2 min), and
humidity sensor should be located as close to the test speci-
8.2.6 Hot air dry.
mens as reasonably possible, in such a way that the air
8.2.7 If there is considerable porosity in the specimens, it is
movement conditions are the same for humidity sensor as for
necessary that they be baked dry for 4 h at a temperature
the test specimens.
greater than 150°C in a clean oven.
6.5.4 Temperature—The ambient temperature, in degrees
NOTE 2—Certain materials could be adversely affected by cleaning in
Celsius, shall be measured and reported during room tempera-
solvents. Deviations from the prescribed cleaning procedure are permitted,
ture tests. In full immersion, liquid-lubricated tests, the bath
but they shall be described in the report.
temperature shall be measured and reported.
8.3 Clean the specimens after they are secured in place in
7. Calibration the test fixture by wiping with acetone and then with methanol-
moistened cotton swabs. It is possible that during mounting,
7.1 The parts of the apparatus that require calibration are
some contamination was inadvertently placed on them, and this
(1) the loading system (2) the motion drive (speed and stroke
final cleaning will help alleviate the problem. Inspect the ball
length), and (3) the friction force sensor.
tip with a hand lens after it is mounted to ensure that there are
7.1.1 Loading System—The load (normal force) applied to
no defects in the contact area.
the specimen shall be checked periodically. In machines which
8.4 Gently lower the ball specimen upon the flat specimen,
apply the load by a spring/lever arrangement and indicate the
and ensure that the reciprocating drive shaft motion is hori-
load on a dial gage, this can be done by substituting a
zontal and parallel to the surface of the flat specimen. The
previously calibrated compression load cell for the specimen
height of the specimen or mount may require adjustment to
and checking the applied load indicated on the loading dial
ensure that this condition is fulfilled. Apply the prescribed test
against the calibrated load cell output. Statically applied loads
load. Confirm that the desired oscillating speed has been set
before turning on the motor.
Participating laboratories were: Oak Ridge National Laboratory, Cameron-Plint
8.5 Two possible testing procedures, one for unlubricated
Ltd. (now Phoenix Tribology Ltd., U. K.), National Research Council (Canada),
tests (Procedure A), and one for high-contact stress-lubricated
General Motors Research—North American Operations, and Caterpillar Technical
tests at elevated temperature (Procedure B), are given in 8.5.1.
Center. Reported measurements of wear groove volume were verified at Oak Ridge
National Laboratory to provide additional checks on the measurements. The procedure appropriate for the given materials and test
NOTICE: This standard has either been superseded and replaced
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