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CVD reviewed
affects backlash, on friction. The paper concludes that, in practice, variation in the coefficient of friction due to changes in backlash can be about five times that estimated theoretically. Wear, Volume 47, Number 1, is published by Elsevier Sequoia SA, POBox 851, 1001 Lausanne 1, Switzerland
Lubricating rolling bearings The popularity of rolling bearings as design elements in mechanical engineering unfortunately presents the user with a serious problem: West German suppliers of machinery produce information sheets using a variety of unstandardized terms. The user of a machine rarely knows the origin of its rolling bearings, which often leads to incorrect installation and in particular to inadequate maintenance. The German Tribological Society formed a working group, chaired by Dr. Pittroff, with leading German manufacturers of rolling bearings, users and scientists equally represented. The group has now presented its results 'the first work sheet for all current rolling bearings, providing answers to practical questions'. Copies of the 24 page work sheet are available, price DM 48.90, from Beuth-Verlag, Koln/Berlin, West Germany
Particle examination Withdrawing equipment from service at regular intervals for preventive maintenance has become increasingly expensive. Interest, therefore, is growing in condition based maintenance. An article by Barwell in the January 1978 issue of Chartered Mechanical Engineer titled 'Particle examination a tool for maintenance engineers' reviews the principles and applications of ferrography. Results from monitoring diesel engines and a large gear box using the Direct Reading Ferrograph are presented and comment made on the value of examining wear particles• The article quotes the results of Jones e t al and Hofman and Johnson who
monitored diesel engines using both ferrography and spectrographic oil analysis. These results indicate that the spectrographic methods are less sensitive than ferrography, and it is suggested that this is due to the insensitivity of spectroscopy to large particles, which are generally of more interest in wear studies.
Selecting hydraulic fluids The March 1978 issue of Chartered Mechanical Engineer contains an article by Hayler and Hampton titled 'Selection of Hydraulic Fluids'• The article begins by briefly outlining the basic hydraulic systems and the demands and limitations they place on the fluids. The bulk of the three page article is devoted to reviewing
Super-Laminar Flow in Bearings Proceedings of the Second Leeds-Lyon Symposium This book gives an excellent summary of the subject of super-laminar flow in bearings, as it stood two and half years ago when the symposium, from which the proceedings derive, succeeded in attracting contributions from most of the centres of expertise in the field• The symposium and proceedings do underline the merit of single topic meetings; the papers were of a high standard, received well-informed discussion and, collectively, manage to give a balanced picture of the state, at least the academic state, of the art.
206
Of the 31 papers, 18 were concerned with theoretical and experimental studies of the nature of flow in liquid films between cylinders and plates subjected to high speed relative movement, and the consequent effects on pressure and friction in the film; eight were concerned with the prediction of the performance of more or less realistic bearing configurations, using empirical data on film flow from various sources; three described tests on actual bearings at high speed; three were on the use of high molecular weight polymer
TRIBOLOGY international June 1978
hydraulic oil properties and the basic fluid types. Finally, there is a short section on selecting hydraulic fluids. Chartered Mechanical Engineer is published by Mechanical Engineering Publications Ltd, PO Box 24, Northgate Avenue, Bury St Edmunds, Suffolk IP32 6BW, UK
CVD reviewed Chemical vapour deposition is one of many methods currently used to coat surfaces to minimise the effects of wear, corrosion, erosion, and high temperature oxidation and diffusion• In the latest issue of International Metals Reviews, Yee discusses CVD protective coatings for metals. The paper reviews the principles and techniques of various CVD processes and examines the applications of CVD protective coatings. A unified approach to the classification of these deposition processes is adopted• Available and developed CVD coatings are surveyed, although organic coatings are not considered. The characteristics, advantages, and disadvantages of CVD are discussed, and finally an assessment made of~he current and future potential. International Metals Reviews, Volume 28, Number 1, is published by The Metals Society, 1 Carlton House Terrace, London SWlY 5DB, UK, and The American Society for Metals, Metals.Park, 44073 Ohio, USA
additives to reduce (by up to 50%) friction in lubricant films; and two were directly concerned with bearing design for high speed. A large number of the papers were concerned with flow characteristics and bearing performance in an intermediate flow regime, between the laminar and turbulent regimes• Flow in this intermediate regime, which is of practical concern because it can cover a wide speed range encompassing many practical bearing applications, is unfortunately complex, involving the formation of organised vortices and waves, the pattern of which alters and becomes more contorted as speed increases. Considerable effort is being applied to describing the flow in
Lubricating rolling bearings The popularity of rolling bearings as design elements in mechanical engineering unfortunately presents the user with a serious problem: West German suppliers of machinery produce information sheets using a variety of unstandardized terms. The user of a machine rarely knows the origin of its rolling bearings, which often leads to incorrect installation and in particular to inadequate maintenance. The German Tribological Society formed a working group, chaired by Dr. Pittroff, with leading German manufacturers of rolling bearings, users and scientists equally represented. The group has now presented its results 'the first work sheet for all current rolling bearings, providing answers to practical questions'. Copies of the 24 page work sheet are available, price DM 48.90, from Beuth-Verlag, Koln/Berlin, West Germany
Particle examination Withdrawing equipment from service at regular intervals for preventive maintenance has become increasingly expensive. Interest, therefore, is growing in condition based maintenance. An article by Barwell in the January 1978 issue of Chartered Mechanical Engineer titled 'Particle examination a tool for maintenance engineers' reviews the principles and applications of ferrography. Results from monitoring diesel engines and a large gear box using the Direct Reading Ferrograph are presented and comment made on the value of examining wear particles• The article quotes the results of Jones e t al and Hofman and Johnson who
monitored diesel engines using both ferrography and spectrographic oil analysis. These results indicate that the spectrographic methods are less sensitive than ferrography, and it is suggested that this is due to the insensitivity of spectroscopy to large particles, which are generally of more interest in wear studies.
Selecting hydraulic fluids The March 1978 issue of Chartered Mechanical Engineer contains an article by Hayler and Hampton titled 'Selection of Hydraulic Fluids'• The article begins by briefly outlining the basic hydraulic systems and the demands and limitations they place on the fluids. The bulk of the three page article is devoted to reviewing
Super-Laminar Flow in Bearings Proceedings of the Second Leeds-Lyon Symposium This book gives an excellent summary of the subject of super-laminar flow in bearings, as it stood two and half years ago when the symposium, from which the proceedings derive, succeeded in attracting contributions from most of the centres of expertise in the field• The symposium and proceedings do underline the merit of single topic meetings; the papers were of a high standard, received well-informed discussion and, collectively, manage to give a balanced picture of the state, at least the academic state, of the art.
206
Of the 31 papers, 18 were concerned with theoretical and experimental studies of the nature of flow in liquid films between cylinders and plates subjected to high speed relative movement, and the consequent effects on pressure and friction in the film; eight were concerned with the prediction of the performance of more or less realistic bearing configurations, using empirical data on film flow from various sources; three described tests on actual bearings at high speed; three were on the use of high molecular weight polymer
TRIBOLOGY international June 1978
hydraulic oil properties and the basic fluid types. Finally, there is a short section on selecting hydraulic fluids. Chartered Mechanical Engineer is published by Mechanical Engineering Publications Ltd, PO Box 24, Northgate Avenue, Bury St Edmunds, Suffolk IP32 6BW, UK
CVD reviewed Chemical vapour deposition is one of many methods currently used to coat surfaces to minimise the effects of wear, corrosion, erosion, and high temperature oxidation and diffusion• In the latest issue of International Metals Reviews, Yee discusses CVD protective coatings for metals. The paper reviews the principles and techniques of various CVD processes and examines the applications of CVD protective coatings. A unified approach to the classification of these deposition processes is adopted• Available and developed CVD coatings are surveyed, although organic coatings are not considered. The characteristics, advantages, and disadvantages of CVD are discussed, and finally an assessment made of~he current and future potential. International Metals Reviews, Volume 28, Number 1, is published by The Metals Society, 1 Carlton House Terrace, London SWlY 5DB, UK, and The American Society for Metals, Metals.Park, 44073 Ohio, USA
additives to reduce (by up to 50%) friction in lubricant films; and two were directly concerned with bearing design for high speed. A large number of the papers were concerned with flow characteristics and bearing performance in an intermediate flow regime, between the laminar and turbulent regimes• Flow in this intermediate regime, which is of practical concern because it can cover a wide speed range encompassing many practical bearing applications, is unfortunately complex, involving the formation of organised vortices and waves, the pattern of which alters and becomes more contorted as speed increases. Considerable effort is being applied to describing the flow in