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Abrasive wear of polymers
BROWN, E. D. The friction and wear of glass. Transactions of the American Society of Lubrication Engineers, Vol 12, No 4 (Oct 1969) pp 227-233 A combination of electron photomicrographs and sensitive friction measurements indicate that the dry friction of glass may be due to surface melting under frictional heat. Stick slip phenomena are examined and the c h a r a c t e r i s t i c 'tear drop' scratch is seen to be composed of a widening track of fused cracks ending in a ' c i r c u l a r spot' of fused glass. Low temperatures or lubrication prevent this. For short durations at low loads, t e m p e r a t u r e s and sliding speeds, most lubricants gave the same friction and wear results. When conditions become m o r e s e v e r e or time more extended v a r i ous c las s es of lubricant excellence can be found. Wear measurements following 'run in' indtcate that with proper lubricants and operating conditions glass bearing surfaces can be operated at high loads and high temperatures. (13 figures, 3 tables, 10 references) (Tribology 1970, abstract 367)
ELLIS, E. G. Testing g r e a s e for ro111n~ bearings. Industrial Lubricatlon, Vol 13, No 1 (1970)pp 14=18 Specifications and performance tests for grease used for rolling contact bearings are outlined. British Timken no longer issue grease specifications but use IP and A S T M standard specifications as well as the Timken wear machine and the S1ell roll stability rig. Hoffmann also have a rig on which water contaminated, high speed, severe load, and hot tests can be done. Skefco have a large range of special application rigs i.e.wheel bearing and railway axlebox. (10 figures, 1 table) (Tribology 1970, abstract 368)
ENGE LMAIER, W. Effects of Imrnishlng on the wear-in and wear life of molybdenum disulfide powders. Lubrication Engineering, Vol 25, No 11 (Nov 1969) pp 442-449 Tests were done using an Alpha LFW-1 test machine to study the effects of burnishing time and load on the amount of MoS 2 deposited, on the endurance limit of the lubrication film, and on the wear - in c h a r a c t e r i s t i c s . The amount of MoS2 deposited increased with burnishing force and burnishing time. The wear-life increased with both burnishing force and burnishing time, but was an otherwise independent linear function of the amount of M o S 2 deposited. (I0 figures, 13 references) (Tribology 1970, abstract 369)
HOPKINS, V. AND CAMPBELL, M. Frictiom and wear life of selected solid f l l m lubricants at --100°F, room temperatare and 400°F. Lubrication Engineering, Vol 25, No 11 (Nov 1969) pp 430-435 Friction and wear life results are presented for 22 solid lubricant films in three contact configurations. The tests used were; the standard Falex load-carrying and w e a r- l i f e tests; flat pellet against flat plate at one sliding speed, v a r i ous loads and environment; journal bearing at 100 r e v / m i n and 3000 lbf/in 2, and at 20 r e v / m i n and 10 000 lbf/in 2. No film was outstanding over the range of tests and the r esu l t s suggest the need match films to specific applications. (8 figures, 2 tables, 9 references) (Tribology 1970, abstract 370)
JOHNSON, K. L. Regimes of elastehydrodynamic lubrication. Journal of Mechanical Engineering Science, Vol 12, No 1 (Feb 1970) pp 9-16 The r e g i m e s of behaviour in the elastohydrodynamic lubrication of r o l l e r s are displayed on a chart whose rectangular coordinates influence the elasticity of the solids and v a r i a tion of viscosity of the lubricant with p r e s s u r e respectively. At small values of these coordinates, i.e. at very light loads, the behaviour is effectively rigid-isoviscous. At high loads
the relative importance of elastic deformation and variable viscosity is shown to depend on a single p a r a m e t e r suggested by Archard. Approximate boundaries for the various r e g i m e s ar e suggested. Using the computer solutions which a r e available, the variations in film thickness and p r e s s u r e distribution in the different r e g i m e s ar e examined. (3 figures, 1 table, 17 references) (Tribology, 1970, abstract 371)
K O R R E N N , H. The axial Ioad-carrylng capacity of radial cylindrical roller bearings. Transactions of the American Society of Mechanical Engineers, Journal of Labrlcation Technology, Vol 92, Series F, No 1 (Jan 1970) pp 129-137 Thrust load transmission at the contact areas of roller ends and flanges occurs under conditions of pure sliding. Recent theoretical and eaperimental investigations showed that with adequately designed roller ends and flanges and with a satisfactory lubricant high thrust loads can be accomodated over a wide speed range with fully hydrodynamic lubrication. The conventional method used for the determination of the safe thrust load should be revised and supplemented. Oil viscosRy should be introduced as an important parameter. Contrary to the present opinion hydrodynamic load-carrying capacity at the flange increases with increasing speed. This new knowledge broadens the application range of radial cylindrical roller bearings. (20 figures) (Tribology 1970, abstract 372)
LANCASTER, J. K. Abrasive wear of poIymers. Wear, Vol 14, No 4 (Oct 1969) pp 223-239 The r o l es of plastic and elastic deformation are discussed and the wear phenomena on abrasive papers, metal gauze and rough metal surfaces are then described. As the counterface topography becomes smoother and/or the surface asp e r i t i e s become less sharp, the wear p r o c e s s for any one polymer changes from cutting on an aspecity scale to surface fatigue. Variations in the mechanical p r o p e r t i e s of polymers also affect the wear p r o c e s s for a given counterface topography, cutting being most important for the rigid polymers and fatigue (or sometimes tensile tearing) for the more elastic polymers. Modifications to a counterface surface during repeated sliding, either by t r a n s f e r or wear, further influence the wear process, and f i l l e r s and reinforcing fibres in a polymer can play an important role in this respect. Finally, three-body abrasion phenomena are considered and an attempt is made to determine the various factors influencing the embeddabllity of abrasive p a r t i c l e s in polymers. (10 figures, 4 tables, 31 references) (Tribology 1970, abstract 373)
LANGBOURNE, P. L. Polymer oil t est s using a Weissenberg rheogonlometer. National Engineering Laboratory Reports, No 440 (1970) As part of a general investigation into the behaviour of nonNewtonian fluids in journal bearings a number of rheogoniom e t e r tests were made on polymer oils formulated by adding various percentages of a proprietary methyl-methacrylate polymer viscosity index improver to a spindle oil. Oils containing these i m p r o v e r s are viscoelastic in nature and can be tested on a rheogoniometer. When the percentage of polym er present is small, as in lubricating oils for Arctic use, an instrument effect of considerable magnitude--the socalled 'negative normal s t r e s s ' - - i s present. The report shows how this effect can "be co r r ect ed for an true (positive) normal s t r e s s values obtained. It concludes that the true normal s t r e s s e s present in Arctic and similar lubricating oils ar e small and unlikely to affect performance in service. (4 figures) (Trtbology 1970, a b s t r a c t 374) TRIBOIX)GY May 1970
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ELLIS, E. G. Testing g r e a s e for ro111n~ bearings. Industrial Lubricatlon, Vol 13, No 1 (1970)pp 14=18 Specifications and performance tests for grease used for rolling contact bearings are outlined. British Timken no longer issue grease specifications but use IP and A S T M standard specifications as well as the Timken wear machine and the S1ell roll stability rig. Hoffmann also have a rig on which water contaminated, high speed, severe load, and hot tests can be done. Skefco have a large range of special application rigs i.e.wheel bearing and railway axlebox. (10 figures, 1 table) (Tribology 1970, abstract 368)
ENGE LMAIER, W. Effects of Imrnishlng on the wear-in and wear life of molybdenum disulfide powders. Lubrication Engineering, Vol 25, No 11 (Nov 1969) pp 442-449 Tests were done using an Alpha LFW-1 test machine to study the effects of burnishing time and load on the amount of MoS 2 deposited, on the endurance limit of the lubrication film, and on the wear - in c h a r a c t e r i s t i c s . The amount of MoS2 deposited increased with burnishing force and burnishing time. The wear-life increased with both burnishing force and burnishing time, but was an otherwise independent linear function of the amount of M o S 2 deposited. (I0 figures, 13 references) (Tribology 1970, abstract 369)
HOPKINS, V. AND CAMPBELL, M. Frictiom and wear life of selected solid f l l m lubricants at --100°F, room temperatare and 400°F. Lubrication Engineering, Vol 25, No 11 (Nov 1969) pp 430-435 Friction and wear life results are presented for 22 solid lubricant films in three contact configurations. The tests used were; the standard Falex load-carrying and w e a r- l i f e tests; flat pellet against flat plate at one sliding speed, v a r i ous loads and environment; journal bearing at 100 r e v / m i n and 3000 lbf/in 2, and at 20 r e v / m i n and 10 000 lbf/in 2. No film was outstanding over the range of tests and the r esu l t s suggest the need match films to specific applications. (8 figures, 2 tables, 9 references) (Tribology 1970, abstract 370)
JOHNSON, K. L. Regimes of elastehydrodynamic lubrication. Journal of Mechanical Engineering Science, Vol 12, No 1 (Feb 1970) pp 9-16 The r e g i m e s of behaviour in the elastohydrodynamic lubrication of r o l l e r s are displayed on a chart whose rectangular coordinates influence the elasticity of the solids and v a r i a tion of viscosity of the lubricant with p r e s s u r e respectively. At small values of these coordinates, i.e. at very light loads, the behaviour is effectively rigid-isoviscous. At high loads
the relative importance of elastic deformation and variable viscosity is shown to depend on a single p a r a m e t e r suggested by Archard. Approximate boundaries for the various r e g i m e s ar e suggested. Using the computer solutions which a r e available, the variations in film thickness and p r e s s u r e distribution in the different r e g i m e s ar e examined. (3 figures, 1 table, 17 references) (Tribology, 1970, abstract 371)
K O R R E N N , H. The axial Ioad-carrylng capacity of radial cylindrical roller bearings. Transactions of the American Society of Mechanical Engineers, Journal of Labrlcation Technology, Vol 92, Series F, No 1 (Jan 1970) pp 129-137 Thrust load transmission at the contact areas of roller ends and flanges occurs under conditions of pure sliding. Recent theoretical and eaperimental investigations showed that with adequately designed roller ends and flanges and with a satisfactory lubricant high thrust loads can be accomodated over a wide speed range with fully hydrodynamic lubrication. The conventional method used for the determination of the safe thrust load should be revised and supplemented. Oil viscosRy should be introduced as an important parameter. Contrary to the present opinion hydrodynamic load-carrying capacity at the flange increases with increasing speed. This new knowledge broadens the application range of radial cylindrical roller bearings. (20 figures) (Tribology 1970, abstract 372)
LANCASTER, J. K. Abrasive wear of poIymers. Wear, Vol 14, No 4 (Oct 1969) pp 223-239 The r o l es of plastic and elastic deformation are discussed and the wear phenomena on abrasive papers, metal gauze and rough metal surfaces are then described. As the counterface topography becomes smoother and/or the surface asp e r i t i e s become less sharp, the wear p r o c e s s for any one polymer changes from cutting on an aspecity scale to surface fatigue. Variations in the mechanical p r o p e r t i e s of polymers also affect the wear p r o c e s s for a given counterface topography, cutting being most important for the rigid polymers and fatigue (or sometimes tensile tearing) for the more elastic polymers. Modifications to a counterface surface during repeated sliding, either by t r a n s f e r or wear, further influence the wear process, and f i l l e r s and reinforcing fibres in a polymer can play an important role in this respect. Finally, three-body abrasion phenomena are considered and an attempt is made to determine the various factors influencing the embeddabllity of abrasive p a r t i c l e s in polymers. (10 figures, 4 tables, 31 references) (Tribology 1970, abstract 373)
LANGBOURNE, P. L. Polymer oil t est s using a Weissenberg rheogonlometer. National Engineering Laboratory Reports, No 440 (1970) As part of a general investigation into the behaviour of nonNewtonian fluids in journal bearings a number of rheogoniom e t e r tests were made on polymer oils formulated by adding various percentages of a proprietary methyl-methacrylate polymer viscosity index improver to a spindle oil. Oils containing these i m p r o v e r s are viscoelastic in nature and can be tested on a rheogoniometer. When the percentage of polym er present is small, as in lubricating oils for Arctic use, an instrument effect of considerable magnitude--the socalled 'negative normal s t r e s s ' - - i s present. The report shows how this effect can "be co r r ect ed for an true (positive) normal s t r e s s values obtained. It concludes that the true normal s t r e s s e s present in Arctic and similar lubricating oils ar e small and unlikely to affect performance in service. (4 figures) (Trtbology 1970, a b s t r a c t 374) TRIBOIX)GY May 1970
121