Editorial
In this issue we have four papers covering different aspects of our field of interest. Mathias Woydt and Norbert Kelling of the Federal Institute for Materials Research and Testing (BAM) in Berlin, Germany describe how they have developed a screening test for engine oils.
Full scale engine testing is both extremely expensive and time consuming. Yet, there seems no acceptable alternative to defining oil performance. Woydt and Kelling highlight the fact that there is in fact disagreement amongst tribologists as to what are the main tribological activities important in the piston/ liner system. This has always been the problem over many years when non-engine tests are proposed to predict how an oil will behave in an engine. However, this is an extremely interesting piece of work undoubtedly being further looked at by all those involved with both oil and engine metallurgy development.
For most of us working in tribology friction leads to heat and wear and our objective is to reduce this occurrence. Our next paper describes work in an area of our science that utilises these "problems". The subject is of course friction welding.
Dr Akata and Dr Sahin working at Trakya University in Turkey provide some very interesting background to this subject and then report on their experimental work. Historically most friction welding has been used where components are of a similar diameter. However, this paper describes research into assessing the strength of welds achieved when different size components are friction welded. It is clear that friction welding as a manufacturing technique will continue to grow and this type of research is vital for us to understand more about the different characteristics of this type of welding.
For both environmental and economic reasons many machine elements are now lubricated with small amounts of lubricant, which will often be additive treated.
Cheng-Hsing Hsu and Hsiu-Lu Chiang of Chung Yuan Christian University and Jaw-Ren Lin of Nanya Institute of Technology in Taiwan, describe their mathematical modelling of this situation. Unlike several previous workers in this area they propose a solution to the non-smooth surface of the bearing and the reality of a non-Newtonian fluids being used as a lubricant.
High-speed gas bearings are increasingly used in precision applications such as drilling printed circuit boards and the similar. Jerry C. T. Su of the National Kaohsiung First University of Science and Technology, and Hsien-I You and Jing-Xain Lai of National Chung-Hin University both in Taiwan present their mathematical model relating to this bearing type. They demonstrate some interesting conclusions including that the geometry of the bearing is more important than the hydrodynamic condition generated by the high speeds. Deductions are also made on the importance of the permeability of the porous bearing and its physical dimensions.
I hope that you will find these papers as interesting as your editor did. I think you will agree that they do represent the high quality and practical research in progress around the world in universities and research institutes.
