ASTM F2661-07(2022)
(Test Method)Standard Test Method for Determining the Tribological Behavior and the Relative Lifetime of a Fluid Lubricant using the Spiral Orbit Tribometer
Standard Test Method for Determining the Tribological Behavior and the Relative Lifetime of a Fluid Lubricant using the Spiral Orbit Tribometer
SIGNIFICANCE AND USE
5.1 Relevance of the Spiral Orbit Tribometer (SOT)—The SOT was designed to evaluate the relative degradation rates of liquid lubricants in a contact environment similar to that in an angular contact bearing operating in the boundary lubrication regime. It functions as a screening device to quickly select the lubricants, evaluate the ability of various components of a lubricant (base oil, thickener, or additive) to lubricate a contact in rolling, pivoting, and sliding conditions simultaneously, and study their chemical decomposition if necessary. The SOT provides a means to study the tribological behavior of oils and greases during operation, while they undergo changes as a function of typical parameters encountered in the lubrication field (temperature, environment, materials used, load applied, and speed). Test conclusion is defined to be when a friction coefficient limit (typically an increase of 0.1 above the steady state value) is surpassed. Normalized lubricant lifetime is then defined as the number of orbits completed divided by the initial amount of lubricant used (in μg). The SOT was initially developed to evaluate lubricants for space applications, but is also relevant for conventional environments. Some results in vacuum are presented (Fig. 1). At this time, no data for tests in ambient conditions have been published (see Fig. 2). The user of this test method should determine to their own satisfaction whether results of this test procedure correlate with field performance or other bench test procedures.
FIG. 1 Relative lifetimes of three typical space lubricants at 23°C in vacuum on 52100 steel
Pepper, S.V., Kingsbury, E.P., “Spiral Orbit Tribometry – Part II: Evaluation of Three Liquid Lubricants in Vacuum”, Tribo. Trans., V 46, 1, pp 65-69, 2003
FIG. 2 Comparison between full scale bearing tests** and SOT data at 23°C on 440C steel.
Bazinet, D.G., Espinosa, M.A., Loewenthal, S.H., Gschwender, L., Jones, W.R., Jr., Predmore, R.E., “Life of Scan...
SCOPE
1.1 This test method covers the quantitative determination of the friction coefficient and the lifetime of oils and greases, when tested on a standard specimen under specified conditions of preparation, speed, Hertzian stress, materials, temperature, and atmosphere, by means of the Spiral Orbit Tribometer (SOT). This test method is intended primarily as an evaluation of the lifetimes of fluid lubricants under vacuum and ambient conditions.
1.2 This standard may involve hazardous materials, operations, and equipment. 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F2661 − 07 (Reapproved 2022)
Standard Test Method for
Determining the Tribological Behavior and the Relative
Lifetime of a Fluid Lubricant using the Spiral Orbit
Tribometer
This standard is issued under the fixed designation F2661; 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 G115Guide for Measuring and Reporting Friction Coeffi-
cients
1.1 This test method covers the quantitative determination
2.2 Anti Friction Bearing Manufacturers Association Stan-
of the friction coefficient and the lifetime of oils and greases,
dards
when tested on a standard specimen under specified conditions
ANSI ABMA ISO 3290(AFBMA Standard 10 Balls)
of preparation, speed, Hertzian stress, materials, temperature,
and atmosphere, by means of the Spiral Orbit Tribometer
3. Terminology
(SOT).This test method is intended primarily as an evaluation
3.1 Definitions:
of the lifetimes of fluid lubricants under vacuum and ambient
3.1.1 coeffıcient of friction—the dimensionless ratio of the
conditions.
friction force between two bodies to the normal force pressing
1.2 This standard may involve hazardous materials,
these bodies together.
operations, and equipment. This standard does not purport to
3.1.2 fixed plate—stationary, horizontal flat plate, typically
address all of the safety concerns, if any, associated with its
through which a force (the “load”) is applied to the ball.
use. It is the responsibility of the user of this standard to
establish appropriate safety, health, and environmental prac- 3.1.3 friction coeffıcient limit—maximum value that the
tices and determine the applicability of regulatory limitations friction coefficient is permitted to attain.
prior to use.
3.1.4 guide plate—physical element that deflects the ball to
1.3 This international standard was developed in accor-
its original orbit radius.
dance with internationally recognized principles on standard-
3.1.5 lubricant total amount— mass of lubricant deposited
ization established in the Decision on Principles for the
on the entire ball surface at the beginning of the test.
Development of International Standards, Guides and Recom-
3.1.6 normalized lifetime—number of ball orbits performed
mendations issued by the World Trade Organization Technical
until the friction coefficient limit is reached divided by the
Barriers to Trade (TBT) Committee.
lubricant total amount initially deposited on the ball.
2. Referenced Documents
3.1.7 rotary plate—flat plate rotating at a constant rate
selected for the test.
2.1 ASTM Standards:
D1193Specification for Reagent Water
3.1.8 scrub zone—Region of the ball’s orbit in which the
F22Test Method for Hydrophobic Surface Films by the
ball is in contact with the guide plate.
Water-Break Test
3.1.9 spiral orbit—track traced by the ball on the fixed and
F2215Specification for Balls, Bearings, Ferrous and Non-
rotating plates of the Spiral Orbit Tribometer. The track has a
ferrous for Use in Bearings, Valves, and Bearing Appli-
spiral shape.
cations
4. Summary of Test Method
1 4.1 Alubricatedballisclampedbetweentwoparallelplates.
This test method is under the jurisdiction ofASTM CommitteeF34 on Rolling
Element Bearings and is the direct responsibility of Subcommittee F34.02 on One of the plates rotates up to 210 rpm, causing the ball to roll
Tribology.
in a near-circular orbit, but is actually an opening spiral. A
Current edition approved Jan. 1, 2022. Published August 2022. Originally
clamping force, the “load”, provides a chosen mean Hertz
approvedin2007.Lastpreviouseditionapprovedin2015asF2661–07(2015).DOI:
stress (typically 1.5 GPa). The system is targeted to operate in
10.1520/F2661-07R22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from American Boiler Manufacturers Association 8221 Old Court-
the ASTM website. house Road, Suite 380 Vienna, Virginia 22182. https://www.abma.com/
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2661 − 07 (2022)
the boundary lubrication regime due to the combination of the developed to evaluate lubricants for space applications, but is
high load, the moderate speed, and the small amount of also relevant for conventional environments. Some results in
lubricant (approximately 50 µg). The ball rolls and pivots in a vacuum are presented (Fig. 1).At this time, no data for tests in
spiral orbit and is maintained in the orbit by the guide plate. ambient conditions have been published (see Fig. 2). The user
The ball slides on the rotating plate when it contacts the guide of this test method should determine to their own satisfaction
plate.Themeasuredforceexertedbytheballontheguideplate whether results of this test procedure correlate with field
is used to determine the friction coefficient. The tribometer performance or other bench test procedures.
runs until the coefficient of friction rises to values much larger
than the initial, steady value.At this point the initial charge of
6. Apparatus
lubricanthasbeendepletedbytribodegradationandthesystem
6.1 The Spiral Orbit Tribometer (SOT)—See Fig. 3.
is running virtually unlubricated. The normalized lifetime is
6.1.1 General description—Fig. 3 shows a schematic draw-
obtained from the number of spiral orbits completed before
ing of a typical SOT. The system consists of a lubricated ball
reaching the chosen friction coefficient limit divided by the
rolling and pivoting between a fixed plate and a rotary plate.
total lubricant mass on the ball at the beginning of the test. A
Theloadisappliedthroughthefixedplate.Thetrackisaspiral
minimum of four tests per lubricant and test condition shall be
andtheballisreturnedtoitsoriginalorbitradiusbycontacting
performed. Lubricants can be compared by calculating their
the guide plate, which forces the ball to return to its original
average normalized lifetimes for a given set of test conditions.
radius each orbit. The friction coefficient is determined by the
measuring the force on the guide plate when the ball contacts
5. Significance and Use
the guide plate. A piezoelectric force transducer is attached to
5.1 Relevance of the Spiral Orbit Tribometer (SOT)—The
the guide plate. This force, divided by twice the normal load,
SOTwas designed to evaluate the relative degradation rates of
is the friction coefficient.
liquid lubricants in a contact environment similar to that in an
6.1.2 Motor drive— A variable speed motor, capable of
angular contact bearing operating in the boundary lubrication
constant speed, is required. Rotating plate speeds are typically
regime. It functions as a screening device to quickly select the
−1
in the range 1 to 210 rpm (0.10 to 22 rad.s ). The effective
lubricants, evaluate the ability of various components of a
stiffness of the axis shall be at least 1.8 E +05 Newton/meter
lubricant(baseoil,thickener,oradditive)tolubricateacontact
axial in the load direction, 3.6 E +08 Newton/meter radial and
in rolling, pivoting, and sliding conditions simultaneously, and
1.13 E +05 Newton-meter/Radian moment. The TIR of the
study their chemical decomposition if necessary. The SOT
motor shaft shall be 0.0254 millimeters maximum.
provides a means to study the tribological behavior of oils and
6.1.3 Fixed load plate— The load plate shall have an axial
greases during operation, while they undergo changes as a
stiffness of at least 1.8 E +08 Newton/meter in the load
function of typical parameters encountered in the lubrication
direction.Theeffectiveradialstiffnessoftheplateaxisshallbe
field (temperature, environment, materials used, load applied,
at least1.8 E+08 Newton/meter and the moment stiffness shall
and speed). Test conclusion is defined to be when a friction
be at least 1.13 E +05 Newton-meter/Radian.
coefficient limit (typically an increase of 0.1 above the steady
state value) is surpassed. Normalized lubricant lifetime is then 6.1.4 Orbit counter— The SOT shall be equipped with a
definedasthenumberoforbitscompleteddividedbytheinitial revolutioncounteroritsequivalentthatwillrecordthenumber
amount of lubricant used (in µg). The SOT was initially of ball orbits.The tribometer would preferably have the ability
Pepper, S.V., Kingsbury, E.P., “Spiral Orbit Tribometry – Part II: Evaluation of Three Liquid Lubricants in Vacuum”, Tribo. Trans., V 46, 1, pp 65-69, 2003
FIG. 1 Relative lifetimes of three typical space lubricants at 23°C in vacuum on 52100 steel
F2661 − 07 (2022)
Bazinet,D.G.,Espinosa,M.A.,Loewenthal,S.H.,Gschwender,L.,Jones,W.R.,Jr.,Predmore,R.E.,“LifeofScannerBearingswithFourSpaceLiquidLubricants”, Proc.
th
37 Aerospace Mech. Symp., Johnson Space Center, May 19-21, 2004
FIG. 2 Comparison between full scale bearing tests** and SOT data at 23°C on 440C steel.
FIG. 3 Detail of the Spiral Orbit Tribometer
to shut off after a pre-selected number of orbits or friction obtained as explained in Section 11. The load cell shall be
coefficient has been reached. linear to within 2% across the entire temperature range of the
6.1.5 Applied load— The fixed plate is attached to a system test.
to apply the load, up to 222.5 N (50 lb.), providing the desired 6.1.6.2 Environment— The SOT operates in either one
Hertzian stress, typically 1.5 GPa. atmosphere air, under a cover gas, or vacuum.When operating
6.1.6 The instruments and gauges: under vacuum or ultrahigh vacuum, a cold cathode pressure
6.1.6.1 Friction force— The friction coefficient is deter- gauge attached to the chamber monitors the pressure. A hot
mined by measuring the force on the guide plate while the ball cathode gauge should be avoided since electrons from the
contacts the guide plate. This force is measured using a filament could alter lubricant chemistry. It is the responsibility
piezoelectric force transducer and a charge amplifier. The oftheusertodeterminethechemicalpurityoftheenvironment
friction force and the coefficient of friction can then be and gas to establish the contribution to tribochemistry.
F2661 − 07 (2022)
6.1.6.3 Measurement of the temperature —When a con- 9. Sampling, Test Specimens, and Test Units
trolled temperature is required, the temperature is monitored
9.1 Test specimens— Specimens (plates, balls, guide plates)
using a thermocouple (for example, K-type) attached to the
will be kept for further analysis, if required.
stationary disk during the test.
9.2 Test units—Only SI units will be used.
7. Reagents and Materials
10. Procedure
7.1 Balls, plates, guide plates. Typical instrument bearing
materials may be of 440C material, but other materials may be
10.1 Cleaningofthepartsandtoolsmaybeanymethodthat
used to simulate the bearing application.
simulates the application. It is recommended that the results of
7.1.1 Test balls—Test balls shall be 12.7 mm (0.5 inch)
cleaning procedures are tested using a water break free test
diameter, grade 25 or better, made with 440C stainless steel.
such as Test Method F22 using reagent grade water per
Their recommended Rockwell hardness shall be 58 to 62. See
Specification D1193, or a wettability test using the intended
Specification F2215 or ANSI ABMA ISO 3290 (AFBMA
oil. Since many variations of cleaning methods exist and their
Standard 10) for ball specification reference. Other materials
results may have a strong effect on the results, it is the user’s
may be used to simulate specific application chemistry.
responsibility to determine the effectiveness and safety of the
7.1.2 Plates, Guide plates—The fixed plate and the rotary
cleaning methods. The details of the cleaning methods shall
plate are disks of 50.8 mm (2 inch) in diameter, may be made
described in the test report.
with 440C stainless steel, or any desired material. Surface
10.2 Lubricationoftheballs—Lubricationofthetestsystem
roughness of 0.05 mm average roughness or less is recom-
is to the ball only.The objective is to lubricate the balls with a
mended. The guide plates are small cylinders 12.7 mm (0.5
small and controlled amount of lubricant.The target amount is
inch in diameter), with a polished surface of 0.05 mm average
ascloseaspossibleto50+/−2µgfora12.7mmdiameterball.
roughness or less (recommended). The recommended Rock-
10.2.1 Lubrication of the balls with oil:
well hardness for 440Cshallbe58to62.Stationary androtary
10.2.1.1 Preparation of a dilute solution of oil:
plates should be made with the same material. Any bearing
(1) Choose a solvent suitable for the oil to be tested. The
material can be used, depending on the application being
user must determine that the solvent does not harm the sample
simulated. The recommended values should be used unless
surface or alter the lubricant.
differences are required to simulate a specific application.
(2) Weigh a clean, dry and empty bottle.
7.1.3 Care must be taken in surface preparation and han-
(3) Put a small drop of oil within the bottle.
dling to avoid surface damage or contamination after cleaning
(4) Note the mass of oil (m ) in milligrams.
that alters the material. Typical cleaning methods may be used oil
(5) Add a volume of solvent in the bottle to obtain the
whentheresultswillpassanTestMethodF22standardtestfor
proportion of one milliliter of solvent per one milligram of oil.
wetability and do not damage the materials or adversely alter
(6) Close the bottle and shake it to create an homogeneous
the sample surfaces. A wettability test using the intended
solution.
lubricant to evaluate the ball and plate cleaning method is
It is the responsibility of the user to determine the type of
recommended.
solvent used. Some solvents may not produce a homogeneous
7.1.4 Reagent grade chemicals shall be used per Test
solution and can have an adverse effect on the results. Care
Method F22 section 8.1. It is the user’s responsibility to
must be taken to produce a final lubricant film that is
preventcontaminationoradulterationofthelubricantsamples,
unadulterated on the ball.
and prevent materials used to clean or lubricate from harming
10.2.1.2 Lubrication of the ball:
the samples.
(1)Weigh a dry, clean ball with a micro-balance to 62 µg.
8. Hazards
(2) Fill a micro-syringe with the dilute oil solu
...
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