ASTM G194 - 25 测量球形物体在平坦水平面上滚动摩擦特性的标准试验方法

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Designation: G194 −25
Standard Test Method for
Measuring Rolling Friction Characteristics of a Spherical
Shape on a Flat Horizontal Plane
1
This standard is issued under the ﬁxed designation G194; 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 the use of an angled launch
ramp to initiate rolling of a sphere or nearly spherical shape,
referred to as the specimen throughout this document, on a ﬂat
horizontal plane, referred to as the rolling surface, to determine
the rolling friction characteristics of a given spherical shape on
a given surface.
1.1.1 Steel balls on a surface plate were used in interlabo-
ratory tests (see Appendix X1). Golf balls on a green, soccer
and lacrosse balls on playing surfaces, bowling balls on a lane,
basketballs on hardwood, and marbles on a composite surface
were tested in the development of this test method, but the test
applies to any specimen rolling on any rolling surface.
1.1.2 The rolling friction of specimens on rolling surfaces is
affected by many factors, including specimen’s stiffness, radius
of curvature, surface texture, the presence of ﬁlms on the
surface, and the nature of the rolling surface. This test method
takes all of these factors into consideration. The specimen of
interest is rolled on the rolling surface of interest using a
standard ramp to initiate rolling and standard techniques are
used to measure and treat the rolled distance after leaving the
ramp.
1.1.3 This test method produces a rolling resistance number
for a speciﬁc specimen on a speciﬁc rolling surface. It is
intended for comparing similar tribosystems. For example, the
rolling resistances of marbles on a particular surface are not to
be compared with the rolling resistance of soccer balls on
grass, because their masses and diameters are very different as
are the rolling surfaces on which they roll.
1.1.4 Different launch ramps are appropriate for different
types of specimens. If a specimen of interest cannot be
accommodated with using one of the launch ramps discussed in
Appendix X1 and Appendix X2, a different launch ramp can be
developed and added with future revisions to this test method.
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 appro-
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
2
G40 Terminology Relating to Wear and Erosion
G115 Guide for Measuring and Reporting Friction Coeffi-
cients
G143 Test Method for Measurement of Web/Roller Friction
Characteristics
3. Terminology
3.1 Deﬁnitions:
3.1.1 rolling friction force, n—in tribology, a force, opposite
to the direction of rolling, resisting rolling of a spherical shape,
ball, roller, wheel, etc. forced against and rolling in a direction
on another surface. G40
3.2 Deﬁnitions of Terms Speciﬁc to This Standard:
3.2.1 coeffıcient of rolling resistance (CORR),
n—dimensionless measure of rolling retardation experienced
by a spherical or nearly spherical specimen on a ﬂat horizontal
plane of interest; it is the ratio of the vertical distance between
the specimen’s point of contact with the launch ramp and the
horizontal plane divided by the distance rolled on the horizon-
tal plane after leaving the launch ramp.
1
This test method is under the jurisdiction of ASTM Committee G02 on
Tribology of Solid Materials and is the direct responsibility of Subcommittee
G02.50 on Friction.
Current edition approved July 1, 2025. Published August 2025. Originally
approved in 2008. Last previous edition approved in 2018 as G194 – 08 (2018).
DOI: 10.1520/G0194-25.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at www.astm.org/contact. For Annual Book of
ASTM Standardsvolume 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
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.
1

3.2.2 rolling resistance number (RR), n—dimensionless

measure of the retardation produced on a spherical or nearly

spherical specimen rolling on a ﬂat horizontal surface: the

higher the number, the higher the retardation; this number is

obtained by multiplying the CORR by 100.

4. Summary of Test Method

4.1 A vee-shaped launch ramp with known height, length,

and vee angle is placed on a ﬂat and level rolling surface of

interest and a specimen (ball bearing, orange, golf ball, etc.) is

rolled down the ramp onto the test surface. The distance

traveled after exiting the ramp is measured. The ratio of the

height of the specimen’s outside diameter above the rolling

surface (horizontal plane) to the distance rolled after leaving

the ramp is the coefficient of rolling resistance. The test

concept is that the potential energy of the specimen raised to a

height (mass × height) is equated to the rolling energy of the

released specimen (mass × distance rolled). The energy is

manifested in distance traveled after leaving the launch ramp.

The distance traveled is the test metric, and this distance is

affected by the nature of the specimen and rolling surface. The

test method can be used to compare the rolling characteristics

of different specimens on a constant rolling surface or a

constant specimen on different rolling surfaces to compare ease

of rolling. Different shaped ramps and angles have been used

for different specimens (Appendix X2). Data developed with

one procedure cannot be readily compared with data developed

using one of the other procedures since the specimens, launch

ramps, and rolling surfaces are different.

5. Signiﬁcance and Use

5.1 Rolling friction like sliding friction depends upon many

factors. It is a system effect that involves the nature of the

specimen and the rolling surface. The sliding friction force (F)

is usually considered to be the sum of forces arising from

deformations of surface features (F

), from attractive forces

(atomic, molecular, etc.) at contact points (F

), and force from

interaction of ﬁlms and particulates on the rubbing surfaces

F5F

(1)

The rolling friction force includes these force contributions

plus effects from the relative stiffness of the contacting

surfaces, the diameter (curvature) of the specimen, and other

factors. Because there are so many factors involved in a rolling

tribosystem, rolling resistance can best be quantiﬁed by an

actual test of the specimen of interest on the intended rolling

surface, as described in this test method.

5.2 There are countless applications where it is important to

quantify the rolling characteristics of a particular spherical

specimen on a particular rolling surface. The interlaboratory

tests conducted for this test method were performed on

hardened steel balls like those used in ball bearings. This test

method could be used to assess the effect of different rolling

surfaces on the rolling characteristics of balls for ball bearings.

Conversely, it could be used as a quality control test on balls.

Surface imperfections/defects/ﬁlms, etc. on the balls can affect

how they roll and thus the distance traveled on a common

rolling surface.

5.3 Industrial applications of this test method can include

assessing conveying surfaces for spherical or nearly spherical

parts: check valve balls, cabinet knobs, Christmas ornaments,

toilet ﬂoats, etc. Many medical devices use special shapes

where rolling characteristics are a consideration. Similarly,

many pharmaceutical products (pills) are spherical or nearly

spherical in shape, and this test method can be used to assess

rolling characteristics for conveying or other reasons such as

size (mass) check.

5.4 Rolling friction of spherical specimens can be a consid-

eration in countless sports (soccer, golf, lacrosse, etc.) and

game applications (billiards, bocce, toys, etc.). This test

method can be used to rank the rolling resistance of different

ball compositions, masses, shapes, surface textures, design,

stiffness, etc. Similarly, the test method can be used to assess

the ease of rolling of balls on different playing or game

surfaces.

5.5 This test method is applicable to spherical or mostly

spherical food products. For example, it is common to use the

rolling distance of apples, citrus fruits, nuts, etc. for size

classiﬁcation in marketing. These items are rolled down an

angled surface and the rolling distance serves as a parameter

for size determination (mass/diameter). Moreover, this test

method can be used to assess the suitability of various rolling

surfaces (such as carpet, metal, wood, etc.) for suitability in

classiﬁcation equipment. Additionally, it could also be used for

food conveyance for spherical-shaped processed foods

(gumballs, hard candy, meatballs, etc.)

5.6 Finally, this test method can be a valuable teaching tool

for physics and tribology students. The equipment is simple,

low-cost, and student proof. It can be used to demonstrate the

concept of rolling friction and the factors that affect it.

6. Apparatus

6.1 A typical launch ramp for small-diameter balls

(<25 mm) is shown in Fig. X2.1. The ramp can be made from

any metal with a cold-ﬁnished surface roughness in the range

of 0.1 µm and 0.3 µm roughness average. Corrosion-resistant

materials (aluminum, stainless steel) are preferred as the

material of construction of the launch ramp since the rolling

surface can be subject to corrosion from rain, dew, handling,

etc.

6.2 Fig. 1 shows a launch ramp schematic that includes the

necessary design elements of a suitable launch ramp. The

distance rolled after the spherical specimen leaves the ramp (d)

is the test metric. These design elements are:

(1) A vee shape to cradle the specimen.

(2) A reference surface that locates the specimen at the top

of the ramp.

(3) A ramp height (h), length (l), and angles (vee and ramp)

(°) suitable for the size and mass of the specimen (Appendix

X2).

(4) The delivery end of the ramp must be tapered to

minimize “drop-off” as the specimen exits the ramp. The end of

the ramp may include a notch, if necessary, to ensure a smooth

transition between the ramp and the rolling surface.

G194 − 25

7. Procedure

7.1 Test Procedure:

7.1.1 Place the launch ramp on the rolling surface of

interest, ideally a ﬂat, horizontal plane, or the most ﬂat and

level portion of a rolling surface.

7.1.2 Remove all obvious ﬁlms and debris due to handling

from the ramp, the specimen, and the rolling surface.

7.1.3 Position the specimen at the top of the launch ramp

touching the reference surface.

7.1.4 Release the specimen without added sideward,

forward, or backward forces. Small specimens can be held with

two ﬁngers and released; large specimens can be held with both

hands, or a device can be used to hold the specimen until

release.

7.1.5 Measure the distance traveled from the launch ramp

end, d, with a meter stick, tape measure, etc. The accuracy of

measurements depends on the intended use and should match

the level of accuracy required for the tribosystem of interest.

7.1.6 Adjust the height of the launch ramp to accommodate

the desired specimen travel distance.

7.1.7 Calculate the coefficient of rolling resistance (CORR)

for the tribosystem using the following equation:

CORR 5h/d(2)

where:

h= the vertical distance between the specimen’s point of

contact with the launch ramp and the rolling surface

(ﬂat, horizontal plane),

d= the distance that the specimen rolled (to a stop) after

exiting the launch ramp, and

RR = CORR may be converted to RR by multiplying by

100. This term may be preferred for some applications

since it usually results in a whole number (after

rounding) that increases with rolling resistance or

rolling friction.

7.2 Ten replicates are recommended. It is not necessary to

use a new travel path for each test if the rolling surface is

robust and not irreversibly deformed during testing.

NOTE 1—The length of the ramp is neglected in the CORR calculation.

Its length is neglected because this length just becomes a constant added

to the (d) measurements made in the test. It does play a role in retarding

the rolling of the specimen and it must be kept clean and debris free. Data

obtained with one ramp should not be compared with data obtained with

a launch ramp with a different height and length.

NOTE 2—To verify that the rolling surface is a ﬂat, horizontal plane free

of angular inﬂuence on the results, the tests may be repeated changing the

rolling direction by approximately 180˚.

NOTE 3—The specimen shall roll in a straight line during the test. If the

specimen deviates from a straight rolling path, by more than a few

diameters depending on its spherical shape, the test shall be considered

invalid and such deviations shall be documented in the test report.

8. Report

8.1 It is important to describe fully the specimen and the

rolling surface. For example, the newness, condition, and

cleanliness of a specimen should be stated along with pertinent

rolling surface conditions such as method of manufacture, and

surface texture. Helpful documents for recording data are

Guide G115 and Test Method G143. A typical test report is

shown in Fig. 2.

9. Precision and Bias

9.1 There is no standard rolling surface that can be evalu-

ated with this test method, therefore, no bias can be deﬁned.

9.1.1 Appendix X1 shows results of interlaboratory tests

conducted with hardened (60 HRC) 52100 steel balls two

different diameters rolling on precision surface plates. The test

balls came from the same lot. The rolling surface plates were

of different materials, but all were level and ﬂat within 50 µm

in 30 cm. The coefficient of variation ranged from 0.02 to

0.108.

9.1.2 Appendix X2.1 contains nonmandatory information

on launch ramps used in the development of this test method.

Coefficient of variation in these tests ranged from 0.04 to 0.12.

9.2 Sources of Variability—Scratches, nicks, and other dis-

continuities and ﬁlms on the specimen, launch ramp, or rolling

surface can affect test results.

10. Keywords

10.1 coefficient of rolling resistance; launch ramp; rolling

friction; rolling surface; spherical specimens

NOTE 1—The launch ramp dimensions used in Option B tests were:

l = 40 cm

h = 13 cm

Vee = 110°

θ= 20°

Material = cold rolled 6061T6 aluminum

FIG. 1 Schematic of a Typical Launch Ramp

G194 − 25

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标签： #标准试验 #测量 #试验方法

摘要：

ASTM G194-25 是一项国际公认的标准试验方法，专门用于精确测量球形物体在平坦水平面上滚动时的摩擦特性。该标准详细规定了测试装置、试样准备、施加载荷、运动速度及数据采集与分析流程，适用于金属、陶瓷、聚合物等多种材质的球体与平面接触系统。通过该试验，可量化滚动摩擦系数、能量损耗及接触变形行为，为轴承设计、材料选型、表面处理工艺优化及摩擦学理论研究提供关键数据支持。标准强调了环境条件控制、重复性验证和结果不确定性分析，确保不同实验室间的数据可比性。该方法的实施有助于工程技术人员评估材料在滚动

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