Film thickness in a ball-on-disc contact lubricated with greases, bleed oils and base oils

Abstract Three different lubricating greases and their bleed and base oils were compared in terms of film thickness in a ball-on-disc test rig through optical interferometry. The theoretical values calculated according to Hamrock's equation are in close agreement with the base oil film thickness measurements, which validates the selected experimental methodology. The grease and bleed oil film thickness under fully flooded lubrication conditions presented quite similar behaviour and levels. Therefore, the grease film thickness under full film conditions might be predicted using their bleed oil properties, namely the viscosity and pressure-viscosity coefficient. The base and bleed oil lubricant parameter LP are proportional to the measured film thickness. A relationship between grease and the corresponding bleed oil film thickness was evidenced.

[1]  Hugh Spikes,et al.  Lubricant Film Thickness in Rough Surface, Mixed Elastohydrodynamic Contact , 2000 .

[2]  R. Larsson,et al.  EHL friction mapping : the influence of lubricant, roughness, speed and slide to roll ratio , 2010 .

[3]  Hugh Spikes,et al.  The behaviour of greases in elastohydrodynamic contacts , 1992 .

[4]  W. 0. Winer,et al.  Correlational Aspects of the Viscosity-Temperature-Pressure Relationship of Lubricating Oils(Dr In dissertation at Technical University of Delft, 1966) , 1966 .

[5]  Erik Höglund,et al.  Starting and Steady-State Friction Torque of Grease-Lubricated Rolling Element Bearings at Low Temperatures—Part II: Correlation with Less-Complex Test Methods , 1996 .

[6]  Hugh Spikes,et al.  Film thickness measurements of lubricating greases under normally starved conditions , 1992 .

[7]  E. Klaus,et al.  Viscosity-Pressure Correlation of Liquids , 1980 .

[8]  Miroslav Liška,et al.  Differential colorimetry: tool for evaluation of chromatic interference patterns , 1997 .

[9]  Jorge H.O. Seabra,et al.  Experimental measuring procedure for the friction torque in rolling bearings , 2010 .

[10]  A. Wilson.  The Relative Thickness of Grease and Oil Films in Rolling Bearings , 1979 .

[11]  B. Hamrock,et al.  Fundamentals of Fluid Film Lubrication , 1994 .

[12]  Hugh Spikes,et al.  The Development of a Spacer Layer Imaging Method (SLIM) for Mapping Elastohydrodynamic Contacts , 1996 .

[13]  N. Fang,et al.  An experimental/theoretical approach to modelling the viscous behaviour of liquid lubricants in elastohydrodynamic lubrication contacts , 2001 .

[14]  R. Larsson,et al.  Elastohydrodynamic lubrication friction mapping – the influence of lubricant, roughness, speed, and slide-to-roll ratio , 2011 .

[15]  W. 0. Winer,et al.  Some Measurements of High Pressure Lubricant Rheology , 1968 .

[16]  S. C. Dodson.  On Use of Grease in Rolling Bearings , 1967 .

[17]  D. Mazuyer,et al.  Nature and Properties of the Lubricating Phase in Grease Lubricated Contact , 2003 .

[18]  D. Mazuyer,et al.  Effects of Grease Composition and Structure on Film Thickness in Rolling Contact , 2003 .

[19]  Henrik Åström,et al.  Video recordings of an EHD point contact lubricated with grease , 1991 .

[20]  Duncan Dowson,et al.  A theoretical analysis of the isothermal elastohydrodynamic lubrication of concentrated contacts. I. Direction of lubricant entrainment coincident with the major axis of the Hertzian contact ellipse , 1985, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[21]  R. B. Dow,et al.  Viscosity-Pressure Characteristics of Lubricating Oils , 1939 .

[22]  S. Poon.  An Experimental Study of Grease in Elastohydrodynamic Lubrication , 1972 .

[23]  Jörg Loos,et al.  Viscosity-pressure-temperature behaviour of mineral oil and synthetic oils , 2001 .

[24]  T. E. Tallian,et al.  Ball bearing lubrication: The elastohydrodynamics of elliptical contacts , 1982 .

[25]  Jorge H.O. Seabra,et al.  Friction and wear in thrust ball bearings lubricated with biodegradable greases , 2011 .

[26]  M Kaneta,et al.  Effects of a thickener structure on grease elastohydrodynamic lubrication films , 2000 .

[27]  Hugh Spikes,et al.  The Measurement and Study of Very Thin Lubricant Films in Concentrated Contacts , 1991 .

[28]  van Hj Harry Leeuwen,et al.  The determination of the pressure—viscosity coefficient of a lubricant through an accurate film thickness formula and accurate film thickness measurements: , 2009 .

[29]  P. Lugt.  A Review on Grease Lubrication in Rolling Bearings , 2009 .

[30]  Jorge H.O. Seabra,et al.  Influence of grease rheology on thrust ball bearings friction torque , 2012 .

[31]  Olov Marklund,et al.  Measuring Lubricant Film Thickness with Image Analysis , 1994 .