ASM Metals HandBook Vol. 8 - Mechanical Testing and Evaluation

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Fig. 13 Four-ball RCF testing apparatus. (See Table 1.) Source: Ref 22

Fig. 14 Ball-on-disk RCF testing apparatus. (See Table 1.) Source: Ref 26

The chapter from STP 771 (Ref 23) that covered NASA John Glenn (Lewis) Research Center's over 20 years of

rolling contact research spans early tests with the fatigue spin rig (Ref 24) developed by NASA to the NASA

five-ball fatigue tester that provided over 500,000 test hours by 1981. Data developed included hardness effects,

influence of compressive residual stress, lubricant types, elastohydrodynamic film thickness influence on life,

along with traction fluids and many other factors with qualitative correlation between the fatigue tester and full-

scale bearing tests (Ref 23).

Unfortunately, G.B. Johnston et al. (Ref 25) revealed different findings in their chapter in STP 771. They had

run full-scale bearing tests (6,309 deep-groove ball bearings and then radial ball bearings with cylindrical inner

rings) and flat washer tests somewhat like the Unisteel rig. Their results from the two last element test methods

did not correlate well with full-scale bearing performance. Their experience does not rule out simpler, single-

element rolling contact rigs but does indicate the need to verify element or simple rig machine data by also

running full-sized related bearing tests. The newer specialized rigs, such as the ball-on-disk machine listed at

the bottom of Table 1 (and shown in Fig. 12), has been able to simulate very specific contact, load/traction

conditions and determine wear difference for rolling with incipient sliding using silicon nitride against different

materials (Ref 26).

The very high contact stresses used in many rig tests can produce different modes of failure. Microstructures

may be altered. Surface coatings and modifications may be destroyed. Failures may be initiated by internal and

surface stress-raising features too small to be of consequence in normal bearing operation. In rigs, the volume

tested may be too small to encounter statistically the macro flaws that often determine bearing life. Rig test

results must be evaluated with careful examination of failures and attention to all tribological conditions.

At the end of this text there are 17 selected references that describe a wide range of rolling contact machines

from recent work to those that started the modern era. These machines and others supply data to the goal of

providing ]an accelerated test that could contribute to better defining the limits of material, manufacture, and

the environment so that significantly longer life could occur in the real applications.

References cited in this section

19. Symposium on Testing of Bearings, American Society for Testing and Materials 49th Annual Meeting,

24–28 June 1946 (Buffalo, NY), American Society for Testing and Materials, p 22–23

20. T. Barish, Fatigue Testing Machines for Ball and Roller Bearings, Symposium on Testing of Bearings,

American Society for Testing and Materials 49th Annual Meeting, 24–28 June 1946 (Buffalo, NY),

American Society for Testing and Materials, 1947, p 19–34

21. P.J. Blau, Rolling Contact Wear, Friction, Lubrication, and Wear Technology, Vol 18, ASM Handbook,

ASM International, 1992, p 258

22. Rolling Contact Fatigue Testing of Bearing Steels, STP 771, J.J.C. Hoo, Ed., ASTM, 198

23. E.V. Zaretsky, R.J. Parker, and W.J. Anderson, NASA Five-Ball Fatigue Tester—Over 20 Years of

Research, Rolling Contact Fatigue Testing of Bearing Steels, STP 771, J.J.C. Hoo, Ed., ASTM, 1982, p

5–45

24. E.F. Macks, The Fatigue Spin Rig, STLE Lub. Eng., Oct 1953, p 254–258

25. G.B. Johnston, T. Andersson, E.V.Amerongen, and A. Voskamp, Experience of Element and Full-

Bearing Testing of Materials over Several Years, Rolling Contact Fatigue Testing of Bearing Steels,

STP 771, J.J.C. Hoo, Ed., ASTM, 1982, p 190–205

26. L.D. Wedeven and N.C. Miller, Material and Tribological Considerations for Turbopump Bearings,

STLE Lub. Eng., Vol 47 (No. 12), Dec 1991, p 1009–1017

Testing of Bearings

Charles A. Moyer, The Timken Company (Retired)

Testing of Sliding Bearings

The 1946 American Society for Testing and Materials symposium also included testing of plain bearings for

automotive engines under a range of operating conditions. These conditions included higher-than-service loads,

constant loads or shock loads, shaft irregularities, and others aimed at shorter duration testing without the

interference of other component failures that might happen in an actual engine. Figure 15 shows a diagram of

the automotive plain bearing test machine. Results achieved included fatigue failure of linings (such as lead-

based babbit), seizure of the lining or corrosion damage, for example, corroded copper lead bearing (Ref 27).

Duplicate bearing tests seemed to show closer agreement, especially for fatigue failures, so that mortality

curves for groups of tests did not seem necessary. The difference between sleeve bearings and rolling bearings

was thought to be primarily due to the ability of sleeve bearing flow under high local stress, thus providing

some stress equalization for sleeve bearings (Ref 27).

Fig. 15 Schematic of sliding bearing test machine. Source: Ref 27

References 28 and 29 came from the same time period as the 1946 symposium and featured hydrodynamic

journal bearings tested under cyclical loading or high-speed operation. The aim of these studies was to provide

experimental data as a check to the theoretical Reynold's number of other theoretical curves. From the

numerous discussions of these papers, it is obvious that the technical community sought worthwhile data to

help explain the dynamic behavior of journal bearings.

In 1968, the Institution of Mechanical Engineers in England had a symposium on experimental methods in

tribology that primarily considered testing methods and measurement techniques. Reference 30, Basic

Principles of Bearing Testing-Machine Design includes simulation ideas for journal and thrust bearings.

References 31, 32, 33, and 34 contain designs and/or explanations of additional rigs for assessing loading

systems, friction, local film pressure, and thickness measurement, stress distributions, merits of rig testing of

materials, and fatigue strength assessment of plain bearings.

Measurement and testing of sliding bearing materials are reviewed in Ref 17. The article covers a wide range of

materials and materials systems, both single metals, such as commercial bronze or porous metal bronze, and

bimetal and trimetal bearing materials systems. Bearing alloy designations and nominal compositions are

described in considerable detail. Because bearing testing aims to expose a specific bearing to similar but more

rigorous conditions than are encountered in service, either speed, load, lubricant amount, or cleanness and

temperature, or several of these parameters, is degraded to cause failures in shorter time. Figure 16 shows two

types of engine bearing test machines that are used to evaluate sliding bearings. As has been stated, in order to

know how such accelerated tests match real world conditions, periodic full-scale bearing tests are still required.

Fig. 16 Schematic showing key components of two types of engine bearing test machines. (a) “Sapphire”

hydraulically loaded machine. (b) Front (left) and side (right) views of Underwood centrifugally loaded

machine. Source: Ref 1

Additional sources that provide experimental plain bearing test rig development and test data are listed in the

Selected References.

References cited in this section

1. T.A. Harris, Friction and Wear of Rolling-Element Bearings, Friction, Lubrication, and Wear

Technology, Vol 18, ASM Handbook, ASM International, 1992, p 499

17. G.R. Kingsbury, Friction and Wear of Sliding Bearing Materials,Friction, Lubrication, and Wear

Technology, Vol 18, ASM Handbook, ASM International, 1992, p 741–757

27. E.T. Johnson, Life Testing of Plain Bearings for Automotive Engines, Symposium on Testing of

Bearings, American Society for Testing and Materials 49th Annual Meeting, 24–28 June 1946 (Buffalo,

NY), American Society for Testing and Materials, Jan 1947, p 2–18

28. E.M. Simons, The Hydrodynamic Lubrication of Cyclically Loaded Bearings (Trans. ASME), Aug 1950,

p 805–816

29. D.F. Wilcock, Turbulence in High-Speed Journal Bearings (Trans. ASME), Aug 1950, p 825–834

30. P.B. Neal, Basic Principles of Bearing Testing-Machine Design, Experimental Methods in Tribology

Proc., 1967–68, Vol 182 (Pt 3G), March 1968, p 24–32

31. C.C.M. Ettles, A Comparison of Some Instrumental Methods for Hydrodynamic Bearings, Experimental

Methods in Tribology Proc., 1967–1968, Vol 182 (Pt 3G), March 1968, p 53–55

32. R.W.T. Preater, Photoelastic Analysis of Journal Bearings: Preliminary Investigations, Experimental

Methods in Tribology Proc., 1967–1968, Vol 182 (Pt 3G), March 1968, p 90–94

33. S.W.E. Earles and D.G. Powell, Considerations in the Design of Plain Sliding Test Rigs, Experimental

Methods in Tribology Proc., 1967–1968, Vol 182 (Pt 3G), March 1968, p 118–121

34. W.H. Wilson, A Test Machine for Assessing the Fatigue Properties of Impulsively Loaded Plain

Bearings, Experimental Methods in Tribology Proc., 1967–1968, Vol 182 (Pt 3G), March 1968, p 129–

131

Testing of Bearings

Charles A. Moyer, The Timken Company (Retired)

References

1. T.A. Harris, Friction and Wear of Rolling-Element Bearings, Friction, Lubrication, and Wear

Technology, Vol 18, ASM Handbook, ASM International, 1992, p 499

2. R. Pike and J.M. Conway-Jones, Friction and Wear of Sliding Bearings, Friction, Lubrication, and

Wear Technology, Vol 18, ASM Handbook, ASM International, 1992, p 515–521

3. M.M. Khonsari and J.Y. Jang, Chapters 61, 62, and 63, Tribology Data Handbook, E.R. Booser, Ed.,

CRC Press, LLC, 1997, p 669–707

4. D. Dowson, History of Tribology, 2nd ed., Professional Eng. Pub., Ltd., London, Edmunds, U.K., 1998

5. R. Stribeck, Kugellager für beliebige Belastungen, Z. Ver. dt. Ing., Vol 45 (No. 3), 1901, p 73–125

6. R. Stribeck, Die Wesentlichen Eigen-schaften der Gleit und Rollenlager, Z. Ver. dt. Ing., Vol 46 (No.

38), 1902, p 1341–8, 1432–8; (No. 39), 1463–70

7. H. Hertz, On the Contact of Elastic Solids, J. reine und angew, Math., Vol 92, 1881, p 156–71

8. J. Goodman, (1) Roller and Ball Bearings, (2) The Testing of Antifriction Bearing Materials, Proc. Inst.

Civ. Engrs., clxxxix, Session 1911-2, Pt. 111, 1912, p 4–88

9. O. Reynolds, On the Theory of Lubrication and Its Application to Mr. Beauchamp Tower's

Experiments, Including an Experimental Determination of the Viscosity of Olive Oil, Philos. Trans. R.

Soc., 177, 1886, p 157–234

10. A.N. Grubin and I.E. Vinogradova, Investigation of the Contact of Machine Components, Book No. 30

(DSIR Trans. No. 337), Kh. F. Ketova, Ed., Central Scientific Research Institute for Technology and

Mechanical Engineering, Moscow, 1949

11. T.E. Tallian, “Progress in Rolling Contact Technology,” Report AL 690007, (SKF) Industries, King of

Prussia, PA, 1969

12. G. Hirn, Sur les principaux Phénomènes qui présentent les frottements médiats, Bull. Soc. ind Mulhouse,

Vol 26, 1854, p 188–277

13. R.H. Thurston, A Treatise on Friction and Lost Work on Machinery and Millwork, 7th ed., Wiley, 1885,

1903

14. N.P. Petrov, Friction in Machines and the Effect of the Lubricant, Inzh. Zh., St. Petersb., 1883, (1) 71–

140, (2) 227–79, (3) 377–436, (4) 533–64

15. B. Tower, Second Report on Friction Experiments (Experiments on the Oil Pressure in a Bearing), Proc.

Inst. Mech. Eng., Jan 1885, p 58–70

16. E.R. Booser,Rolling vs Sliding Bearings, Product Eng., McGraw Hill, 1964, p 731