ASTM G182-13(2018)
(Test Method)Standard Test Method for Determination of the Breakaway Friction Characteristics of Rolling Element Bearings
Standard Test Method for Determination of the Breakaway Friction Characteristics of Rolling Element Bearings
SIGNIFICANCE AND USE
5.1 This test is a simple, effective way of determining the ability of bearings to roll freely. Most bearing manufacturers do not supply information on the breakaway friction coefficient of their products and if this is a design factor, users often buy candidate bearings and try them until they find one that appears to operate freer than the others. This test allows quantification of the breakaway friction characteristics of bearings. This test assesses the friction of a bearing as a tribosystem which includes its construction and lubrication. It has shown to correlate with use. If a bearing has a low breakaway angle in this test, its breakaway friction will be lower in service than the same size bearings that displayed a higher breakaway angle in this test.
5.2 Breakaway friction of bearings is important in instruments where forces are light and the bearings are used as pivots rather than for continued rotation. Low friction is often imperative for proper device operation.
5.3 Bearings with low breakaway friction are often sought for web handling rollers. Many rollers are driven only by tangential web contact and slippage can often damage the web. Low friction bearings are required.
5.4 This test is useful for screening bearings for any applications where breakaway friction is a design concern.
SCOPE
1.1 This test method is an extension of Test Method G164 and uses an inclined plane and a paperclip rider to detect the presence or absence of lubricants on the surfaces of flexible webs. A study to identify free spinning or low rolling friction bearings indicated that the paperclip friction test could be used for rolling friction by simply replacing the paperclip with a rolling element bearing on an axle. The angle of the inclined plane at initiation of rolling is the breakaway angle. This test method can be used to measure the angle at breakaway of small diameter (up to 100 mm outside diameter) rolling element bearings. The bearings that have been tested in the development of this method are conventional ball bearings with different separators, seals, and different conditions of lubrication (none, oil, greases, and so forth), but there is no technical reason why this test method would not work with bearings of other design, including plain bearings. Rolling element bearings like any sliding system can have friction characteristics at breakaway that are different than rolling continuously. As is the case with most inclined plane friction tests, the test only produces the friction characteristic at the onset of measurable rolling, using the angle (θ) when measurable rolling commences. The objective of this test is an assessment of breakaway rolling friction characteristics to assist machine designers in the selection of rolling element bearings for instrument pivots and the like where breakaway friction is a concern.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 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: G182 − 13 (Reapproved 2018)
Standard Test Method for
Determination of the Breakaway Friction Characteristics of
Rolling Element Bearings
This standard is issued under the fixed designation G182; 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 ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
1.1 This test method is an extension of Test Method G164
mendations issued by the World Trade Organization Technical
and uses an inclined plane and a paperclip rider to detect the
Barriers to Trade (TBT) Committee.
presence or absence of lubricants on the surfaces of flexible
webs. A study to identify free spinning or low rolling friction
2. Referenced Documents
bearings indicated that the paperclip friction test could be used
2.1 ASTM Standards:
for rolling friction by simply replacing the paperclip with a
G40 Terminology Relating to Wear and Erosion
rolling element bearing on an axle. The angle of the inclined
G117 Guide for Calculating and Reporting Measures of
plane at initiation of rolling is the breakaway angle. This test
Precision Using Data from Interlaboratory Wear or Ero-
methodcanbeusedtomeasuretheangleatbreakawayofsmall
sion Tests (Withdrawn 2016)
diameter (up to 100 mm outside diameter) rolling element
G143 Test Method for Measurement of Web/Roller Friction
bearings. The bearings that have been tested in the develop-
Characteristics
ment of this method are conventional ball bearings with
G164 Test Method for Determination of Surface Lubrication
different separators, seals, and different conditions of lubrica-
on Flexible Webs
tion (none, oil, greases, and so forth), but there is no technical
reason why this test method would not work with bearings of
3. Terminology
other design, including plain bearings. Rolling element bear-
3.1 Definitions Relating to Wear and Erosion (taken from
ings like any sliding system can have friction characteristics at
Terminology G40):
breakawaythataredifferentthanrollingcontinuously.Asisthe
3.1.1 coeffıcient of friction, µ—in tribology, the dimension-
case with most inclined plane friction tests, the test only
less ratio of the friction force (F) between two bodies to the
produces the friction characteristic at the onset of measurable
normal force (N) pressing these bodies together.
rolling, using the angle (θ) when measurable rolling com-
mences. The objective of this test is an assessment of break-
3.1.2 friction force—the resisting force tangential to the
awayrollingfrictioncharacteristicstoassistmachinedesigners
interface between two bodies when, under the action of
in the selection of rolling element bearings for instrument
external force, one body moves or tends to move relative to the
pivots and the like where breakaway friction is a concern.
other.
1.2 The values stated in SI units are to be regarded as
3.1.3 kinetic coeffıcient of friction—the coefficient of fric-
standard. No other units of measurement are included in this
tion under conditions of macroscopic relative motion between
standard.
two bodies.
1.3 This standard does not purport to address all of the
3.1.4 lubricant—any substance interposed between two sur-
safety concerns, if any, associated with its use. It is the
facesforthepurposeofreducingthefrictionand wearbetween
responsibility of the user of this standard to establish appro-
them.
priate safety, health, and environmental practices and deter-
3.2 Definitions Not Covered by Terminology G40:
mine the applicability of regulatory limitations prior to use.
3.2.1 breakaway coeffıcient of rolling friction—the force in
1.4 This international standard was developed in accor-
the direction of rolling (F) required to produce rolling of a
dance with internationally recognized principles on standard-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method is under the jurisdiction of ASTM Committee G02 on Wear contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
and Erosion and is the direct responsibility of Subcommittee G02.50 on Friction. Standards volume information, refer to the standard’s Document Summary page on
CurrenteditionapprovedJune1,2018.PublishedJuly2018.Originallyapproved the ASTM website.
in 2006. Last previous edition approved in 2013 as G182 – 13. DOI: 10.1520/ The last approved version of this historical standard is referenced on
G0182-13R18. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G182 − 13 (2018)
NOTE 1—User must determine weight and center of gravity. All components to be made from brass or steel.
FIG. 1 Suggested Balancing Arm
shape that is capable of rolling on a surface, divided by the lubrication.Thisthistestcouldalsobeusedtoevaluatebearing
normal force (N) on the rolling shape:
designs and bearing greases.
F
µ rolling 5 (1)
5. Significance and Use
N
3.2.2 inclined plane—asurfacethatcanberaisedatanangle
5.1 This test is a simple, effective way of determining the
to produce motion of an object on the plane.
ability of bearings to roll freely. Most bearing manufacturers
3.2.3 plain bearings—a cylindrical shape used to support a donotsupplyinformationonthebreakawayfrictioncoefficient
rotating shaft. of their products and if this is a design factor, users often buy
candidatebearingsandtrythemuntiltheyfindonethatappears
3.2.4 rolling element bearing—balls or rollers in raceways
to operate freer than the others. This test allows quantification
that support a shaft and allow rotation of the shaft or bearing
of the breakaway friction characteristics of bearings. This test
outer race (OD).
assesses the friction of a bearing as a tribosystem which
4. Summary of Test Method includes its construction and lubrication. It has shown to
correlate with use. If a bearing has a low breakaway angle in
4.1 This test method can be used to measure the breakaway
thistest,itsbreakawayfrictionwillbelowerinservicethanthe
rolling friction characteristics of rolling element bearings.
same size bearings that displayed a higher breakaway angle in
4.2 Small rolling element bearings (less than 100 mm
this test.
outside diameter) are affixed to a balanced rider and placed on
an incline. The rider is designed so that it becomes the axle 5.2 Breakaway friction of bearings is important in instru-
about which the bearing rotates. The inclined plane is raised mentswhereforcesarelightandthebearingsareusedaspivots
(by hand or mechanism) until the outer race (OD) of the
rather than for continued rotation. Low friction is often
bearing starts to roll on the inclined plane. The inclined plane
imperative for proper device operation.
surface is covered with a plasticized PVC tape to increase the
5.3 Bearings with low breakaway friction are often sought
static friction between the outside surface of the bearing and
for web handling rollers. Many rollers are driven only by
inclined plane. The test will not yield rolling friction charac-
tangential web contact and slippage can often damage the web.
teristics if the bearing slides rather than rolls on the inclined
Low friction bearings are required.
plane.
5.4 This test is useful for screening bearings for any
4.3 The rolling friction characteristics measured by this test
are the net result of the bearing design, materials and stat
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.