World Tribology Congress, 8-12 September 1997

Citation

(1998), "World Tribology Congress, 8-12 September 1997", Industrial Lubrication and Tribology, Vol. 50 No. 1. https://doi.org/10.1108/ilt.1998.01850aab.016

World Tribology Congress, 8-12 September 1997

World Tribology Congress, 8-12 September 1997

This conference was planned, and generally well executed, as the biggest international tribology event ever. It was supported by 35 associated bodies from five continents and attended by over 1,100 delegates and contributors from 52 countries; 75 per cent of attendees were from overseas. This reflected the decision of the organisers of the ASME (American Society of Mechanical Engineers) and STLE (Society of Tribologists and Lubrication Engineers) events, Eurotrib '97 and Nordtrib '97 to integrate with the Congress. The meeting marked the 150th anniversary of the founding of the Institution of Mechanical Engineers on 17 January 1847, in Birmingham and the 60th anniversary of the first major international lubrication and wear conference, also organised by the Institute of Mechanical Engineers, which was held in London on 13-15 October 1937. In anticipation of a large attendance the sessions of the conference were centred on the Methodist Central Hall, Westminster, where its forerunner had been staged 60 years before. The historical perspective is interesting.

Instead of the World Tribology Congress, the 1937 event was more modestly called "A General Discussion on Lubricants and Lubrication" and had the utilitarian objectives of "reviewing the present state of the science and practice of lubrication in order to correlate theory and pure research with practice, to consider methods of bearing design, to obtain current views on bearing metals, and to bring out the significance of laboratory tests, including friction and wear tests". The aims of the more recent congress could be criticised for being too introspective with insufficient emphasis on demonstrating the value of tribology to industry and the national economy. In all, 136 papers were presented at the 1937 meeting and, with the co-operation of 31 home scientific and technical bodies and 22 from overseas, there were as many as 600 registered delegates although only around 500 actually attended. Supporting the 1937 meeting was an exhibition, staged at the Science Museum, Kensington, with the backing of industry, which attracted 18,300 visitors over three weeks. The published Proceedings of the General Discussion provided a valuable account of the pre-war state of the science and application of tribology 30 years before the word tribology was coined. Preparation for the Second World War, which started less than two years later, delayed the immediate benefits which should have resulted from the conference. The next major international tribology conference was not held until 1957, 20 years later.

Presentations

The 1997 event included an opening address, five plenary presentations, 33 invited papers, nearly 350 oral presentations in five parallel sessions and around 450 poster papers. In all, nearly 840 papers were presented in four-and-a-half days. Many more papers had been submitted, making for difficult decisions over which to select. Prizes for the best poster paper of the day were awarded. Delegates received a 500-page hardback volume of the plenary and invited papers entitled New Directions in Tribology and a 913-page volume of one-page abstracts of the oral and poster papers. Many of the papers will be published in full over the next few months in one or other of the 20 participating tribology journals, of which Industrial Lubrication and Tribology is one. A poster paper from the Centro Sviluppo Materiali in Rome, entitled "Tribological characterisation of composite powder metallurgical materials for the valve train components of heavy duty diesel engines under starved or unlubricated lubrication conditions" appeared in the September/October issue of this journal.

Plenary papers

By encouraging registration on the previous evening, the congress was able to open at 08.30 on the Monday morning, with a welcome by Dr Bill Roberts, chairman of the Organising Committee of the Tribology Group of the IMechE. In his opening address, Dr H. Peter Jost, president of the International Tribology Council, stated what he saw as the three principal objectives of the congress:

(1) There should be a presentation of the latest state of research and development in tribology.

(2) It should provide an opportunity for tribologists from all over the world to meet, exchange views and make contacts; and

(3) It should strengthen links with end-users.

Dr Jost emphasised the importance of tribology's role in the economics and competitiveness of industry. He felt that education and the industrial application of advances in tribology were being neglected. Governments had to be reminded constantly of the national economic benefits of the application of tribology. The full text of Dr Jost's address is included in this issue. Later, at the congress banquet, Dr Jost was presented with a new international award of the STLE, in recognition of his outstanding services to tribology throughout the world. Professor D. Dowson, University of Leeds, presented the first plenary paper, on the historical perspective of tribology in the twentieth century. The second edition of his acclaimed History of Tribology is to be published early in 1998. From the USA, Ward Winer's paper dealt with thin film elastohydrodynamically lubricated traction under very high pressures and high shear rate viscometry at pressures up to 600 MPa. It concluded that the Reynolds equation was valid for the mechanics of a piezoviscous fluid only when the shear stress x the pressure viscosity coefficient were much less than unity. K. Kato, Japan, reviewed the subject of wear, together with current and future methods for its control. Michael Neale, a leading tribology consultant and a former President of the IMechE, related the progress of tribology in meeting the needs of industry since 1966. His conclusion was that progress had been disappointing, with a few notable exceptions which he outlined. He made constructive suggestions how to change the focus of tribological research to enhance its value to industry. J-M Georges, France, surveyed progress in the understanding of the properties and structure of tribological surfaces and their interaction at the molecular and atomic level.

Invited papers

Thirty-three well respected workers from 15 countries were invited to contribute papers related to achievements in their fields of interest. The subjects ranged from nano-tribology (three papers by B. Bhushan, N.D. Spencer et al. and J.B. Pethica et al. on the study of contacts and relative motion on a sub-micrometre scale) to problems in the chemical process industry and a methodology for investigating component failures (Summers-Smith).

Laboratory scale bench test simulation of tribological contacts was the subject of papers by P. Blau and A.F. Alliston-Greiner.

A. Ball and K.-H. Zum Gahr wrote about abrasive wear, the former in aggressive mining environments and the latter on the theory and on laboratory wear test results.

The application of lubrication models to engines (R.C. Coy), micro-elastohydrodynamic lubrication (B. Jacobson), thin film and boundary lubrication (H. Spikes), the structure, properties and use of layered-lattice solid lubricants (M.N. Gardos) and the impact of liquid lubricants on the environment (W.J. Bartz) were well reviewed.

The state-of-the-art of plain bearing lubrication analysis and design was reported by M. Tanaka while developments in the prediction of rolling element bearing life as part of a system was the topic of the paper by E. Ioannides. Polymeric bearing materials were reviewed in four papers: polyethylene for orthopaedic joint prostheses (A. Wang et al.), rubber and plastics in general (S.W. Zhang), polytetrafluoroethylene and polyphenylene sulphide (Y. Uchiyama et al.) and scratch testing (B.J. Briscoe). Tribochemical effects with ceramics were described by T.E. Fischer and ceramics figured largely in M. Woydt's contribution on the oil-free engine.

Hostile environments were experienced in hot metal forming (J.H. Benyon), spacecraft (P.D. Fleischauer) where air is a hostile environment for molybdenum disulphide films and low volatility synthetic oils are the preferred lubricant, in the USA.

The tribology of thin coatings, especially diamond-like carbon (K. Holmberg et al.), duplex surface diffusion hardened and coated surfaces (T. Bell) and oxide layers (F.H. Stott) was described.

Papers on wear featured wear-mechanism maps (S.C. Lim), wear particle morphology (G.W. Stachowiak) and wear tests for thin coatings (I.M. Hutchings).

Maintenance techniques in Japan were reviewed by Y. Kimura, N.K. Myshkin described methods of surface contact modelling and K.C. Ludema outlined the essential elements for success in teaching tribology.

The congress

Each day started with the presentation of an invited paper in the main hall before splitting into five parallel sessions. The session topics are shown in Table I.

There were some surprising gaps in the list of topics as well as in the range of subjects covered in the papers offered. Apart from Dr Bartz's review paper, one on biodegradable lubricants and a paper on environmental aspects of cutting processes there was little directly relevant to the wide ranging impact of current environmental awareness on tribology. Elsewhere there were papers on rapeseed oil as a gear lubricant, the effect of additives on olive oil and high oleic sunflower oil and two papers on esters, with environmental implications (pages 29, 120, 121, 31 and 33 respectively). In a search for environmentally compatible (ash-free) additives researchers from Switzerland found that some additives were strongly dependent on the type of base oil (ester or polyalphaolefin), the bearing material and the concentration (page 119). There were five papers on perfluoroalkylpolyethers (pages 26, 34-37).

Inappropriate topic allocation

Many papers had been placed under inappropriate topics.

There were papers under the Practical Applications heading on automotive engine fuel economy and friction reduction in motor vehicles which might more usefully have been grouped under Automotive. There were several more papers on aspects of seals than the four listed above. Three of them had been placed in the Practical Applications topic and one, on the surface topography of seal faces, had been misplaced under Lubricant Chemistry and Rheology. Another misplaced paper was on cavitation erosion of plain journal bearings placed under Wear by Hard Particles instead of under Thick Film Bearings. In the paper on cavitation the researchers concluded that, of the four types ­ flow, impact, suction and discharge:

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  flow cavitation erosion but not impact cavitation could be reduced by smoothing the end of the oil groove;

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  aluminium tin was more cavitation resistant than lead alloy overlays; and

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  flow and impact cavitation can be reduced by increased contents of free air in the oil.

There were no separate topics for gears, transmissions or brakes ­ again the nine papers on these subjects had been lumped under Practical Applications. There were four papers on wear maps, one the invited paper under Thermal Effects, two under Wear by Hard Particles (pages 222 and 241) and the fourth under Manufacturing and Maintenance (page 340).

Thick film bearings

Judged by the number of papers, thick film bearings was the most popular topic. It included 13 pages on tilting pad bearings, 20 on plain journal bearings, eight on gas bearings and four each on face seals and rotor dynamics. A review from BF Goodrich Aerospace (BFG) (page 94) traced 75 years of water lubricated rubber bearings practice and theory from the use of a piece of rubber hose to replace a failed pump bearing in a flooded Californian gold mine to today's heavy duty, environmentally friendly elastomer bearings for machinery. The author showed the benefits of using a "slippery polymer alloy" (SPA) in comparison with other materials in Table II.

There was a great deal of interest in the papers from Cranfield University on aerostatic (page 19) and water hydrostatic (page 95) porous ceramic bearings for ultra precision high speed machine tools. The well-known problems with porous bearings of unpredictable flow and instability caused by dead volumes have been tackled by the use of two layers of porous medium with different pore sizes or by the production of a controlled porous structure from carefully graded ceramic powder by hot isostatic pressing and sintering. A prototype 50 × 50mm bearing test rig made by the second method has been tested at up to 16,000rpm with water.

PTFE replaces whitemetal

Two papers, appearing under different topic headings, were on replacing whitemetal by PTFE (polytetrafluoroethylene) as linings for large thrust bearing pads. In the Indian paper (page 836) a 2mm thick filled PTFE layer bonded to a steel backing gave 40 per cent lower friction and wear down to a quarter of the wear of whitemetal. Tests were under boundary lubricated conditions, 0.3 MPa load, lubricated with turbine oil. PTFE + 55 per cent bronze + 5 per cent graphite gave the best results. The other, more significant, application was prompted by the reported success in the former Soviet Union of PTFE lined thrust pads. Most hydro-electric turbines in the former Soviet Union now have PTFE lined thrust bearings instead of whitemetal. The benefits have been fewer failures, lower friction, no need for high pressure forced lubrication jacking at low speeds and higher load capacity (6.5 MPa compared to 3.5 MPa for whitemetal). After factory trials in Newcastle of a bearing liner comprising PTFE sheet pressed into wire coils to a depth of up to 1.5mm, a set of PTFE faced pads with an area of 1.07m² was installed in a pump storage unit at the Ffestiniog power station, North Wales in 1996. A further installation is planned at Dinorwig in 1998, one of Europe's largest power plants.

Tribology of magnetic storage systems

One subject that certainly would not have been discussed at the 1937 meeting was magnetic storage systems. This topic attracted a great deal of interest, and concentrated on the lubrication and wear of the contacts between magnetic hard discs, the principal magnetic storage media in computers and their recording head sliders. Problems are:

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  demand for lower flying head heights to increase data storage density increasing the risk of asperity contacts at the head/disc or head/tape interface;

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  excessive friction, termed stiction, during start up of discs, aggravated by the demand for ever smoother disc surfaces;

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  lubricant depletion, followed by asperity polishing and then burnishing wear.

Perfluoropolyether lubricants applied to amorphous carbon protective coatings on magnetic discs to give a film or polymer a few nanometres thick are commonly used. Contact stop/start (CSS) testing is used to evaluate the friction and wear characteristics of discs and sliders. Contact recording where the head and disc/tape are in nominal contact is seen to be the trend for the future.

The ever increasing need for data storage capacity and decreasing package size has meant that the data densities demanded for magnetic media (discs and tapes) are increasing by about 60 per cent every year. At present hard discs are made with surface finishes as good as 1.2nm Ra; they run with a lubricant thickness between disc and head of 3nm, have a storage density of 3 Gbytes per square inch and are guaranteed for five years. In the future densities of up to 50 Gbytes per square inch will be the target requiring "contact recording" with the head in contact with the disc or tape. The tribology of this system is a major limitation. Having the head as close as possible to the disc or tape is the aim because, for example, a 10nm gap results in the loss of 2 dB of signal. Experience with ceramic heads made up of two layers of calcium titanate with a soft magnetic material between them in contact with magnetic tape has shown a problem of three body abrasive wear resulting in the hollowing out of the soft centre of the head. The cause was ceramic particles becoming embedded in the magnetic tape acting as abrasives. The fracture toughness of the ceramic was identified as the most important property affecting the wear.

Patron, sponsors and exhibitors

HRH Prince Philip, Duke of Edinburgh was the congress patron.

Sponsors of the congress were NSK-RHP (rolling element bearing manufacturer), AEA Technology (parent company of the National Centre of Tribology), GKN (the world's biggest manufacturer of constant velocity joints), Climax Molybdenum (marketer of molybdenum disulphide solid lubricant) and Pall Industrial Hydraulics (filter manufacturer).

Forty-three organisations had or shared exhibition stands at the congress. They included:

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  12 publishers (ASME, Baltzer, Elsevier, ESDU, Finnish Society for Tribology, Fuels and Lubes, Institute of Materials, Leaf Coppin, LNG, MCB University Press, MEP, and STLE);

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  ten test equipment manufacturers (Analex, CETR, CSEM, Ducom, Falex, Nano, PCS, Plint, Prosm and Tannas);

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  four lubricant manufacturers (Balmer Lawrie, Neste, K.S. Paul and Raisio);

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  four bearing manufacturers (Ampep, Kingsbury, Koyo and NSK-RHP);

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  nine consulting/research organisations (AEA Technology, BICERI, Center for Tribology, Danish Technology Institute, Institute for Terotechnology, MiTi, National Physical Laboratory, Savant, Tampere University and VTT);

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  one surface coating company (Balzers);

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  one filter manufacturer (Pall);

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  one software producer (ITECH); and

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  one foundry (JOT).

New Directions in Tribology, editor I.M. Hutchings, Mechanical Engineering Publications, 1997, 500 pages, hard cover, ISBN 1 86058 099 8; price £98.00.

World Tribology Congress Abstracts, Mechanical Engineering Publications, 1997, 912 pages, soft cover, ISBN 1 86058 109 9, price: £149.00.

Mechanical Engineering Publications Limited, Northgate Avenue, Bury St Edmunds, Suffolk IP32 6BW. Tel: 01284 724384; Fax: 01284 704006.