ASTM G133-05(2016)

Standard Test Method for Linearly Reciprocating Ball-on-Flat Sliding Wear

SIGNIFICANCE AND USE
5.1 This test method is designed to simulate the geometry and motions that are experienced in many types of rubbing components whose normal operation results in periodic reversals in the direction of relative sliding. The wear resulting from this mode of movement may differ from that experienced by the same materials sliding continuously in only one direction (unidirectional sliding) even for comparable durations of contact. Test loads and speeds are to be determined by the severity of the proposed application or purpose of the testing. Either of two sets of testing conditions (designated Procedures A and B) may be used.
SCOPE
1.1 This test method covers 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.

General Information

• Status: Historical
• Publication Date: 31-May-2016
• ICS: 19.060 - Mechanical testing
• Technical Committee: G02 - Wear and Erosion
• Drafting Committee: G02.40 - Non-Abrasive Wear

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: G133 − 05 (Reapproved 2016)
Standard Test Method for
Linearly Reciprocating Ball-on-Flat Sliding Wear
This standard is issued under the fixed designation G133; 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 Precision Using Data from Interlaboratory Wear or Ero-
sion Tests
1.1 This test method covers laboratory procedures for de-
G118Guide for Recommended Format of Wear Test Data
termining the sliding wear of ceramics, metals, and other
Suitable for Databases
candidate wear-resistant materials using a linear, reciprocating
ball-on-flat plane geometry. The direction of the relative
3. Terminology
motion between sliding surfaces reverses in a periodic fashion
such that the sliding occurs back and forth and in a straight 3.1 Definitions:
line. The principal quantities of interest are the wear volumes
3.1.1 Definitions used in this test method are given in
ofthecontactingballandflatspecimenmaterials;however,the Terminology G40. The following definitions of important
coefficient of kinetic friction may also be measured using the
termsusedinthistestmethodarecitedfromTerminologyG40.
method described. This test method encompasses both unlu- 3.1.2 friction force—the resisting force tangential to the
bricated and lubricated testing procedures. The scope of this
interface between two bodies when, under the action of an
test method does not include testing in corrosive or chemically externalforce,onebodymovesortendstomoverelativetothe
aggressive environments.
other.
3.1.3 Hertzian contact pressure—themagnitudeofthepres-
1.2 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information sure at any specified location in a Hertzian contact area, as
calculated from Hertz’s equations of elastic deformation.
only.
1.3 This standard does not purport to address all of the 3.1.4 wear—damage to a solid surface, generally involving
theprogressivelossofmaterialduetorelativemotionbetween
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- that surface and a contacting surface or surfaces.
priate safety and health practices and determine the applica-
3.1.5 wear rate—the rate of material removal or dimen-
bility of regulatory limitations prior to use.
sional change due to wear per unit of exposure parameter, for
example, quantity removed (mass, volume, thickness) in unit
2. Referenced Documents
distance of sliding or unit time.
2.1 ASTM Standards:
E112Test Methods for Determining Average Grain Size 4. Summary of Test Method
E1181Test Methods for Characterizing Duplex Grain Sizes
4.1 This test method involves two specimens—a flat speci-
G40Terminology Relating to Wear and Erosion
menandasphericallyendedspecimen(hereincalledthe“ball”
G99Test Method for Wear Testing with a Pin-on-Disk
specimen) which slides against the flat specimen. These
Apparatus
specimens move relative to one another in a linear, back and
G115Guide for Measuring and Reporting Friction Coeffi-
forth sliding motion, under a prescribed set of conditions.
cients
4.2 In this test method, the load is applied vertically
G117Guide for Calculating and Reporting Measures of
downward through the ball specimen against the horizontally
mounted flat specimen. The normal load, stroke length, fre-
quency and type of oscillation, test temperature, lubricant (if
This test method is under the jurisdiction of ASTM Committee G02 on Wear
any), test duration, and atmospheric environment (including
and Erosion and is the direct responsibility of Subcommittee G02.40 on Non-
Abrasive Wear.
relative humidity range) are selected from one of two proce-
Current edition approved June 1, 2016. Published June 2016. Originally
dures.
approved in 1995. Last previous edition approved in 2010 as G133–05 (2010).
DOI: 10.1520/G0133-05R16.
4.3 Since this test method involves reciprocating sliding
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
where changes in the sliding velocity and direction of motion
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
occur during the test, constant velocity conditions are not
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. maintained.The manner in which the velocity varies with time
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G133 − 05 (2016)
FIG. 1 Reciprocating Test—Schematic Diagram
isdeterminedbythedesignofthemechanismwhichdrivesthe the ball and the flat. Temperature measurement and control
ball or flat specimen back and forth. capability is provided to heat and monitor the flat specimen
which may either be immersed in a lubricant bath or tested
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
5. Significance and Use frictional resistance of the specimens at maximum load, is
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
salsinthedirectionofrelativesliding.Thewearresultingfrom
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
(unidirectional sliding) even for comparable durations of 6.3 BallandBallSpecimenHolder—Theballspecimenmay
be a fixed bearing ball or any spherically tipped specimen as
contact. Test loads and speeds are to be determined by the
severity of the proposed application or purpose of the testing. longastheslidingcontactisequivalenttoaballonaflatplane.
If a bearing ball is used, it shall be clamped tightly enough to
Either of two sets of testing conditions (designated Procedures
A and B) may be used. preventslippageduringthetest.Theballholdershouldberigid
enough so that the periodic reversal in the sliding direction
6. Apparatus
does not result in tilting or other misalignment 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
tipwhichmovesbackandforthacrossthesurfaceofapolished
specimenarepossible.Theprimarycriterionisthatthecoupon
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-
faces.Alternate configurations in which the flat moves and the
Machines of this type are described in A Catalogue of Friction and Wear
ball specimen is fixed may be used. A provision is made for
Devices, American Society of Lubrication Engineers (now STLE) 838 Busse
applying a uniform normal force (load) to the contact between Highway, Park Ridge, IL, 1973, pp. 50–72.
G133 − 05 (2016)
6.5 Instrumentation: normal force would be 60.5 N. During oscillating tests, the
6.5.1 Friction Force—A tension-compression load cell or normalforcemayvaryslightlyaboutthemeanvalueduetothe
similar force-sensing device may be used to measure the dynamics of the machine. This variation is to be expected.
friction forces generated during sliding. Calibration of the 7.1.2 Motion Drive—The oscillating frequency of the mov-
frictionforce(seesubsection7.1.3)inbothforwardandreverse ing specimen shall be checked periodically against the drive
slidingdirectionsisrequired.Sincethedirectionofthefriction motor setting to ensure that the rate of oscillation is known.
force changes rapidly during the test, traditional strip-chart- (Warning—Due to inertial effects, differences in the loading
typerecordersmaybetooslowtofollowthesechangesathigh andfixturingmethodbecomemoresignificantastheoscillating
frequencies of reciprocation. A commercial version of this frequency of the test is increased, and harmonic frequencies
machine is available with a signal conditioner to rectify, and characteristic of the test machine must be avoided when
output the root-mean-square friction force to a strip-chart- selecting the oscillating frequency.)
recorder or to a computerized data acquisition system. The 7.1.3 Friction Force Sensor—Thefrictionforcesensorshall
method of sensing and recording friction force during the test becalibratedperiodicallyinbothdirectionsofloadapplication.
shall be described in the testing report. Depending on the machine, a fixture which applies a calibrat-
6.5.2 Test Duration—In this test method, test duration is ing load in line with the normal point of contact between the
specifiedinseconds.Tocomputetheslidingdistanceinmetres ball and flat should be used.
or number of cycles, use the following:
8. Procedure
X 50.002 3t 3f 3L (1)
8.1 Specimen Preparation—The ball specimen and flat
or
specimen shall be used either in a polished condition, or in a
N 5 t 3f (2)
specified condition consistent with the application of interest.
In a polished condition, the surface should be as free as
where:
possible from preparation artifacts such as grinding-induced
X = total sliding distance of the ball, m,
cracks, gross grinding marks, and grain pull-out. Surface
N = number of cycles in the test,
roughnesses of 0.02 to 0.05-µm R (arithmetic roughness) are
a
t = test time, s,
typical.
f = oscillating frequency, Hz (cycles/s), and
L = length of stroke, mm.
8.2 Clean the specimens using the following procedure:
A cycle is defined as two stroke lengths (up and back). 8.2.1 Wash with a mild liquid laboratory glassware cleaner,
8.2.2 Hot air dry,
Electronic timers can be used to terminate the test. If a
cycle-counter is available, this may be used instead of the 8.2.3 Ultrasonically clean in acetone (2 min),
8.2.4 Hot air dry,
timer, in which case Eq 2 will be used.
6.5.3 Humidity—The wear and friction of many materials is 8.2.5 Ultrasonically clean in methanol (2 min), and
8.2.6 Hot air dry.
significantly affected by the moisture in the air. It is therefore
requiredthattherelativehumidity(toanaccuracyof 63%)be 8.2.7 If there is considerable porosity in the specimens, it is
necessary that they be baked dry for4hata temperature
measured before and during the test. Humidity can vary with
air flow and in different parts of the same room, so the greater than 150°C in a clean oven.
humidity sensor should be located as close to the test speci-
NOTE 1—Certain materials could be adversely affected by cleaning in
mens as reasonably possible, in such a way that the air
solvents.Deviationsfromtheprescribedcleaningprocedurearepermitted,
movement conditions are the same for humidity sensor as for but they shall be described in the report.
the test specimens.
8.3 Clean the specimens after they are secured in place in
6.5.4 Temperature—The ambient temperature, in degrees
thetestfixturebywipingwithacetoneandthenwithmethanol-
Celsius, shall be measured and reported during room tempera-
moistened cotton swabs. It is possible that during mounting,
ture tests. In full immersion, liquid-lubricated tests, the bath
somecontaminationwasinadvertentlyplacedonthem,andthis
temperature shall be measured and reported.
final cleaning will help alleviate the problem. Inspect the ball
tip with a hand lens after it is mounted to ensure that there are
7. Calibration
no defects in the contact area.
7.1 The parts of the apparatus that require calibration are
8.4 Gently lower the ball specimen upon the flat specimen,
(1) the loading system, (2) the motion drive (speed and stroke
and ensure that the reciprocating drive shaft motion is hori-
length), and (3) the friction force sensor.
zontal and parallel to the surface of the flat specimen. The
7.1.1 Loading System—The load (normal force) applied to
height of the specimen or mount may require adjustment to
thespecimenshallbecheckedperiodically.Inmachineswhich
ensure that this condition is fulfilled.Apply the prescribed test
apply the load by a spring/lever arrangement and indicate the
load. Confirm that the desired oscillating speed has been set
load on a dial gage, this can be done by substituting a
before turning on the motor.
previously calibrated compression load cell for the specimen
and checking the applied load indicated on the loading dial 8.5 Two possible testing procedures, one for unlubricated
against the calibrated load cell output. Statically applied loads tests (ProcedureA), and one for high-contact stress-lubricated
shall be kept constant within a maximum deviation of 62.0% tests at elevated temperature (Procedure B), are given in 8.5.1.
ofthetestload.Forexample,permittedstaticerrorofa25.0-N The procedure appropriate for the given materials and test
G133 − 05 (2016)
severity should be selected. If neither procedure in 8.5.1 is 8.6 Alternative Testing Procedures—To achieve certain
determined to be suitable, other conditions may be used, but simulation conditions, or for other technical reasons, Proce-
testingwillnotbeincompliancewiththistestmethod.Seethe dures A and B may not be suitable for a given reciprocating
reporting requirements in Section 10 for reporting exceptions wear testing project. Modifications to the specific test condi-
to Procedures A and B. tions prescribed in Procedures A and B may be used for
8.5.1 The two testing procedures are as follows. conducting such tests; however, in reporting the results, the
specific parameters which are not in compliance with one of
8.5.1.1 Procedure A—Unlubricated wear testing at room
the standard testing procedures shall be specifically noted. A
temperature.
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: G133 − 05 (Reapproved 2010) G133 − 05 (Reapproved 2016)
Standard Test Method for
Linearly Reciprocating Ball-on-Flat Sliding Wear
This standard is issued under the fixed designation G133; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers 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.
2. Referenced Documents
2.1 ASTM Standards:
E112 Test Methods for Determining Average Grain Size
E1181 Test Methods for Characterizing Duplex Grain Sizes
G40 Terminology Relating to Wear and Erosion
G99 Test Method for Wear Testing with a Pin-on-Disk Apparatus
G115 Guide for Measuring and Reporting Friction Coefficients
G117 Guide for Calculating and Reporting Measures of Precision Using Data from Interlaboratory Wear or Erosion Tests
G118 Guide for Recommended Format of Wear Test Data Suitable for Databases
3. Terminology
3.1 Definitions:
3.1.1 Definitions used in this test method are given in Terminology G40. The following definitions of important terms used in
this test method are cited from Terminology G40.
3.1.2 friction force—the resisting force tangential to the interface between two bodies when, under the action of an external
force, one body moves or tends to move relative to the other.
3.1.3 Hertzian contact pressure—the magnitude of the pressure at any specified location in a Hertzian contact area, as calculated
from Hertz’s equations of elastic deformation.
3.1.4 wear—damage to a solid surface, generally involving the progressive loss of material due to relative motion between that
surface and a contacting surface or surfaces.
3.1.5 wear rate—the rate of material removal or dimensional change due to wear per unit of exposure parameter, for example,
quantity removed (mass, volume, thickness) in unit distance of sliding or unit time.
4. Summary of Test Method
4.1 This test method involves two specimens—a flat specimen and a spherically ended specimen (herein called the “ball”
specimen) which slides against the flat specimen. These specimens move relative to one another in a linear, back and forth sliding
motion, under a prescribed set of conditions.
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-Abrasive Wear.
Current edition approved April 1, 2010June 1, 2016. Published April 2010June 2016. Originally approved in 1995. Last previous edition approved in 20052010 as
ε1
G133G133 – 05 (2010).–05 . DOI: 10.1520/G0133-05R10.10.1520/G0133-05R16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G133 − 05 (2016)
4.2 In this test method, the load is applied vertically downward through the ball specimen against the horizontally mounted flat
specimen. The normal load, stroke length, frequency and type of oscillation, test temperature, lubricant (if any), test duration, and
atmospheric environment (including relative humidity range) are selected from one of two procedures.
FIG. 1 Reciprocating Test—Schematic Diagram
4.3 Since this test method involves reciprocating sliding where changes in the sliding velocity and direction of motion occur
during the test, constant velocity conditions are not maintained. The manner in which the velocity varies with time is determined
by the design of the mechanism which drives the ball or flat specimen back and forth.
4.4 Dimensional changes for both ball and flat specimens are used to calculate wear volumes and wear rates.
4.5 Friction forces are measured during the test and may be used to assess changes in the contact conditions or the kinetic
friction coefficient as a function of time.
5. Significance and Use
5.1 This test method is designed to simulate the geometry and motions that are experienced in many types of rubbing
components whose normal operation results in periodic reversals in the direction of relative sliding. The wear resulting from this
mode of movement may differ from that experienced by the same materials sliding continuously in only one direction
(unidirectional sliding) even for comparable durations of contact. Test loads and speeds are to be determined by the severity of the
proposed application or purpose of the testing. Either of two sets of testing conditions (designated Procedures A and B) may be
used.
6. Apparatus
6.1 General Description—Fig. 1 shows the arrangement for the reciprocating ball-on-flat wear test available on a commercial
machine. The ball is rigidly mounted and has a spherical tip which moves back and forth across the surface of a polished flat
specimen. Use of a spherical tip alleviates the alignment problems associated with flat-ended balls sliding on flat surfaces. Alternate
configurations in which the flat moves and the ball specimen is fixed may be used. A provision is made for applying a uniform
normal force (load) to the contact between the ball and the flat. Temperature measurement and control capability is provided to
heat and monitor the flat specimen which may either be immersed in a lubricant bath or tested without lubricant. The tangential
force can be measured continuously during oscillating contact and used to obtain friction coefficient data.
Machines of this type are described in A Catalogue of Friction and Wear Devices, American Society of Lubrication Engineers (now STLE) 838 Busse Highway, Park
Ridge, IL, 1973, pp. 50–72.
G133 − 05 (2016)
6.2 Specimen Drive—A drive train, capable of providing smooth, reciprocating motion to the ball and overcoming the frictional
resistance of the specimens at maximum load, is required. For example, a Scotch yoke drive mechanism can provide a smooth,
sinusoidal velocity profile for the ball specimen relative to the flat specimen without the need for the motor to stop and reverse
direction periodically. Stepper-type motors may also be used provided that the motion is smooth and uniform.
6.3 Ball and Ball Specimen Holder—The ball specimen may be a fixed bearing ball or any spherically tipped specimen as long
as the sliding contact is equivalent to a ball on a flat plane. If a bearing ball is used, it shall be clamped tightly enough to prevent
slippage during the test. The ball holder should be rigid enough so that the periodic reversal in the sliding direction does not result
in tilting or other misalignment of the contact.
6.4 Flat Specimen Holder—The flat specimen is secured to the base of the machine to prevent slippage or buckling during the
test. A variety of shapes and configurations for the flat specimen are possible. The primary criterion is that the coupon present a
flat, horizontal surface to the ball specimen.
6.5 Instrumentation:
6.5.1 Friction Force—A tension-compression load cell or similar force-sensing device may be used to measure the friction
forces generated during sliding. Calibration of the friction force (see subsection 7.1.3) in both forward and reverse sliding
directions is required. Since the direction of the friction force changes rapidly during the test, traditional strip-chart-type recorders
may be too slow to follow these changes at high frequencies of reciprocation. A commercial version of this machine is available
with a signal conditioner to rectify, and output the root-mean-square friction force to a strip-chart-recorder or to a computerized
data acquisition system. The method of sensing and recording friction force during the test shall be described in the testing report.
6.5.2 Test Duration—In this test method, test duration is specified in seconds. To compute the sliding distance in metres or
number of cycles, use the following:
X 5 0.002 3t 3f 3L (1)
or
N 5 t 3f (2)
where:
X = total sliding distance of the ball, m,
N = number of cycles in the test,
t = test time, s,
f = oscillating frequency, Hz (cycles/s), and
L = length of stroke, mm.
A cycle is defined as two stroke lengths (up and back). Electronic timers can be used to terminate the test. If a cycle-counter
is available, this may be used instead of the timer, in which case Eq 2 will be used.
6.5.3 Humidity—The wear and friction of many materials is significantly affected by the moisture in the air. It is therefore
required that the relative humidity (to an accuracy of 63 %) be measured before and during the test. Humidity can vary with air
flow and in different parts of the same room, so the humidity sensor should be located as close to the test specimens as reasonably
possible, in such a way that the air movement conditions are the same for humidity sensor as for the test specimens.
6.5.4 Temperature—The ambient temperature, in degrees Celsius, shall be measured and reported during room temperature
tests. In full immersion, liquid-lubricated tests, the bath temperature shall be measured and reported.
7. Calibration
7.1 The parts of the apparatus that require calibration are (1) the loading system, (2) the motion drive (speed and stroke length),
and (3) the friction force sensor.
7.1.1 Loading System—The load (normal force) applied to the specimen shall be checked periodically. In machines which apply
the load by a spring/lever arrangement and indicate the load on a dial gage, this can be done by substituting a previously calibrated
compression load cell for the specimen and checking the applied load indicated on the loading dial against the calibrated load cell
output. Statically applied loads shall be kept constant within a maximum deviation of 62.0 % of the test load. For example,
permitted static error of a 25.0-N normal force would be 60.5 N. During oscillating tests, the normal force may vary slightly about
the mean value due to the dynamics of the machine. This variation is to be expected.
7.1.2 Motion Drive—The oscillating frequency of the moving specimen shall be checked periodically against the drive motor
setting to ensure that the rate of oscillation is known. (Warning—Due to inertial effects, differences in the loading and fixturing
method become more significant as the oscillating frequency of the test is increased, and harmonic frequencies characteristic of
the test machine must be avoided when selecting the oscillating frequency.)
7.1.3 Friction Force Sensor—The friction force sensor shall be calibrated periodically in both directions of load application.
Depending on the machine, a fixture which applies a calibrating load in line with the normal point of contact between the ball and
flat should be used.
G133 − 05 (2016)
8. Procedure
8.1 Specimen Preparation—The ball specimen and flat specimen shall be used either in a polished condition, or in a specified
condition consistent with the application of interest. In a polished condition, the surface should be as free as possible from
preparation artifacts such as grinding-induced cracks, gross grinding marks, and grain pull-out. Surface roughnesses of 0.02 to
0.05-μm R (arithmetic roughness) are typical.
a
8.2 Clean the specimens using the following procedure:
8.2.1 Wash with a mild liquid laboratory glassware cleaner,
8.2.2 Hot air dry,
8.2.3 Ultrasonically clean in acetone (2 min),
8.2.4 Hot air dry,
8.2.5 Ultrasonically clean in methanol (2 min), and
8.2.6 Hot air dry.
8.2.7 If there is considerable porosity in the specimens, it is necessary that they be baked dry for 4 h at a temperature greater
than 150°C in a clean oven.
NOTE 1—Certain materials could be adversely affected by cleaning in solvents. Deviations from the prescribed cleaning procedure are permitted, but
they shall be described in the report.
8.3 Clean the specimens after they are secured in place in the test fixture by wiping with acetone and then with
methanol-moistened cotton swabs. It is possible that during mounting, some contamination was inadvertently placed on them, and
this final cleaning will help alleviate the problem. Inspect the ball tip with a hand lens after it is mounted to ensure that there are
no defects in the contact area.
8.4 Gently lower the ball specimen upon the flat specimen, and ensure that the reciprocating drive shaft motion is horizontal
and parallel to the surface of the flat specimen. The height of the specimen or mount may require adjustment to ensure that this
condition is fulfilled. Apply the prescribed test load. Confirm that the desired oscillating speed has been set before turning on the
motor.
8.5 Two possible testing procedures, one for unlubricated tests (Procedure A), and one for high-contact stress-lubricated tests
at elevated temperature (Procedure B), are given in 8.5.1. The procedure appropriate for the given materials and test severity should
be selected. If neither procedure in 8.5.1 is determined to be suitable, other conditions may be used, but testing will not be in
compliance with this test method. See the reporting requirements in Section 10 for reporting exceptions to Procedures
...