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Gas-lubricated bearings
SYSTEMSTIC AHSTRACTS agreement with experimental data. Amplitudes of steady motion at rotational angular velocities nearly equal to the natural circular frequency of the system are analysed. The various typical response curves calculated are compared with those obtained from experiments. The Development and Performance of Reticular 20% Tin- Aluminium Bearings. P. G. Forrester, M. J. Neale and A. D. Newman, Proc. Inst. Mech. Engrs., 175 (IO) (1961) 5377561; Appl. Mech. Rev., ‘5 (8) (1962) 682. Journal Bearing Calculations, Heat Flow and Variable Load. (in German) K. Meiners, VDI-Forschungsh., 488 (1961) 48 pp., 66 fig., 33 ref., 170 equations; Appl. Mech.
Rev.,
‘5
(9) (1962)
760,
The first paper dealswith the flow of heat from a journal bearing, the second paper with the movement of a stationary shaft in a journal bearing consequent on impulse loading is given, together with some useful simple approximations for the movement of its axis as a function of the “impulse Sommcrfeld variable”. Comparison of Metals for Use as Unlubricated Journal Bearings. F. F. A. Simpson, Proc. Inst. Mech. Engrs., 175 (IO) (1961) 528-536; Appl. Mech. Rev., r5 (8) (1962) 681. A number of materials have been run as unlubricated plain journal bearings, against mild-steel journals, at a number of combinations of load P and speed V sufficient to cause failure within IOO hours. For each material the bearing life for various values of
87
P and V giving the same product were similar, but the materials differed greatly in the P and l’ value which resulted in similar bearing lives. Polytetrafluoroethylene-lead-bronze appeared to be outstanding, supporting PV values as much as 30 times greater than those that resulted in a similar life for other materials and surface treatments commonly used as unlubricated bearings. The performance characteritics of the various materials are commented on. Gas-Lubricated Bearings. W. A. Gross, survey in Appl. Mech. 15 (IO) (1962) 765-769; 48 rets.
Rev.,
Gas-Lubricated Cylindrical Journal Bearings of Finite Length-Static Loading. R. Sternlicht, ,I. Appl. Mech. (ASME Trans., Ser. E), 83 (1961) 535-543; ‘5
(7)
(1962)
.4ppl.
Mech.
Rev.,
597.
Viscous Torque in a Spherical Gas Bearing. T. F. Yeh, J. Aerospace Sci., 29 (2) (1962) 160-161;
Appl.
Mech.
Rev.,
15 (7) (1962)
597.
The Design of Air Bearings and Their Application to Measuring Instruments and Machine Tools. H. L. Wunsch, Intern. ,I. Mach. Tool Design Res., I (3) (1961) 1988212; Appl. Mech. Rev., 15 (IO) (1962) 845. Applications where air bearings of the externally pressurized type have advantageous properties. Examples: (I) Machine tool slideways, (2) lead-screw measuring bench, (3) roundness-measuring instrument, (4) power dynamometer, (5) testing machine for highspeed ball-bearings.
5. WEAR AND WEAR RESISTANCE The Size Distribution of Wear Fragments: Effect of SurfaceEnergy on theWear Process. E. Rabinowicz and R. G. Foster, (Mass. Inst. Technology, Cambridge, Mass.) (1962) 47 pp., 18 refs.; N 62-12266, T.P.,4., 2 (7) (1962) 328. The size of loose wear particles formed during the sliding of two materials is equal to 60,000 W,,/p, where Wti is the surface energy of adhesion and p the penetration hardness. Experimental results are presented which show that the experimental particle sizes obtained with many materials do indeed obey the theoretical relationship and that the particle size is, as predicted, almost independent of such external variables as speed, load, time, and geometry. Indeed, il particles of the wrong size are fed into the system, then they are rapidly broken down or built up until the correct size is reached. However, changes of atmosphere and the use of lubricants, which alter the energy of adhesion, do have a marked influence on
wear particle size, and this fact suggests a possible use of wear particle measurement to rate boundary lubricants. Other suriacc interaction phenomena which are governed by the W/p ratio are derived, and it is suggested that the surface roughness generated during sliding is a function of this ratio. To be published in Trans. A.S.M.E.; see also l+‘eav, 2 (r958/59) 4. Mechanism of Wear of Nonmetallic Materials. C. H. Riesz and H. S. Weber, (Wright Patterson ,4FB, Ohio, Directorate of Materials and Processes), (1962) 27 pp., 24 refs.; N 62-16038, T.P.A., 2 (16) (1962) 929. Friction and wear of single-crystal sapphire surfaces were studied at 10-6 mm Hg over a temperature range of 25°~1550”C. Highest coefficients of friction were found at ambient temperature, particularly when basal planes were in sliding contact. Under certain conWear, 6 (1963) 81-90
Rev.,
‘5
(9) (1962)
760,
The first paper dealswith the flow of heat from a journal bearing, the second paper with the movement of a stationary shaft in a journal bearing consequent on impulse loading is given, together with some useful simple approximations for the movement of its axis as a function of the “impulse Sommcrfeld variable”. Comparison of Metals for Use as Unlubricated Journal Bearings. F. F. A. Simpson, Proc. Inst. Mech. Engrs., 175 (IO) (1961) 528-536; Appl. Mech. Rev., r5 (8) (1962) 681. A number of materials have been run as unlubricated plain journal bearings, against mild-steel journals, at a number of combinations of load P and speed V sufficient to cause failure within IOO hours. For each material the bearing life for various values of
87
P and V giving the same product were similar, but the materials differed greatly in the P and l’ value which resulted in similar bearing lives. Polytetrafluoroethylene-lead-bronze appeared to be outstanding, supporting PV values as much as 30 times greater than those that resulted in a similar life for other materials and surface treatments commonly used as unlubricated bearings. The performance characteritics of the various materials are commented on. Gas-Lubricated Bearings. W. A. Gross, survey in Appl. Mech. 15 (IO) (1962) 765-769; 48 rets.
Rev.,
Gas-Lubricated Cylindrical Journal Bearings of Finite Length-Static Loading. R. Sternlicht, ,I. Appl. Mech. (ASME Trans., Ser. E), 83 (1961) 535-543; ‘5
(7)
(1962)
.4ppl.
Mech.
Rev.,
597.
Viscous Torque in a Spherical Gas Bearing. T. F. Yeh, J. Aerospace Sci., 29 (2) (1962) 160-161;
Appl.
Mech.
Rev.,
15 (7) (1962)
597.
The Design of Air Bearings and Their Application to Measuring Instruments and Machine Tools. H. L. Wunsch, Intern. ,I. Mach. Tool Design Res., I (3) (1961) 1988212; Appl. Mech. Rev., 15 (IO) (1962) 845. Applications where air bearings of the externally pressurized type have advantageous properties. Examples: (I) Machine tool slideways, (2) lead-screw measuring bench, (3) roundness-measuring instrument, (4) power dynamometer, (5) testing machine for highspeed ball-bearings.
5. WEAR AND WEAR RESISTANCE The Size Distribution of Wear Fragments: Effect of SurfaceEnergy on theWear Process. E. Rabinowicz and R. G. Foster, (Mass. Inst. Technology, Cambridge, Mass.) (1962) 47 pp., 18 refs.; N 62-12266, T.P.,4., 2 (7) (1962) 328. The size of loose wear particles formed during the sliding of two materials is equal to 60,000 W,,/p, where Wti is the surface energy of adhesion and p the penetration hardness. Experimental results are presented which show that the experimental particle sizes obtained with many materials do indeed obey the theoretical relationship and that the particle size is, as predicted, almost independent of such external variables as speed, load, time, and geometry. Indeed, il particles of the wrong size are fed into the system, then they are rapidly broken down or built up until the correct size is reached. However, changes of atmosphere and the use of lubricants, which alter the energy of adhesion, do have a marked influence on
wear particle size, and this fact suggests a possible use of wear particle measurement to rate boundary lubricants. Other suriacc interaction phenomena which are governed by the W/p ratio are derived, and it is suggested that the surface roughness generated during sliding is a function of this ratio. To be published in Trans. A.S.M.E.; see also l+‘eav, 2 (r958/59) 4. Mechanism of Wear of Nonmetallic Materials. C. H. Riesz and H. S. Weber, (Wright Patterson ,4FB, Ohio, Directorate of Materials and Processes), (1962) 27 pp., 24 refs.; N 62-16038, T.P.A., 2 (16) (1962) 929. Friction and wear of single-crystal sapphire surfaces were studied at 10-6 mm Hg over a temperature range of 25°~1550”C. Highest coefficients of friction were found at ambient temperature, particularly when basal planes were in sliding contact. Under certain conWear, 6 (1963) 81-90