Friction and wear testing machines to evaluate tomorrow's lubricants

Friction and wear testing machines to evaluate tomorrow's lubricants

ABSTRACTS Copies of origiwl nrficles ore besl obloittcd by wiling dirrcl lo Ike joumnl in w/tick they oppenred. Tke qddrcsses of jountals cm be fotozd...

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ABSTRACTS Copies of origiwl nrficles ore besl obloittcd by wiling dirrcl lo Ike joumnl in w/tick they oppenred. Tke qddrcsses of jountals cm be fotozd in n 1-eJerence book suck as ‘World Lisl oJ’ Screul(fic rind Techicnl Publicnliom’. r Williugs Press Guide I ’ Netuspoper Press Direclorv’ md Jo+ Amen’can jorcnrols o?tly, ‘Ayers’. ADINOFF, B. Grease evaluation for wedge brakes. Lubrication Engineering, Vol 24, No 9 (September 1968) pp 416-421 A high quality grease, formerly used in the wedge-type brake, failed to protect the internal parts from corrosion in case of a seal failure. Analysis of the problem led to the conclusion that several special properties were required for this application. A programme was initiated to test commercially-available greases for these properties. Eleven greases were examined. The special requirements included: protection of steel in 5% salt spray; protection of steel in a condensing humidity cabinet; resistance to flow at 300°F; resistance to hardening at 300°F; resistance to water washout; and low shear strength at 40°F. The test methods are described and the data compared with field service experience. Five greases are considered to be satisfactory. (1 figure, ‘I tables) (Tribology 1969,abstract 193)

AIDA,T.,ODA,S.,KUSANO,K.,ITO,Y. Bending fatigue strength of case-hardened gears. Bulletin of the Japan Society of Mechanical Engineers, Vol. 11, No. 44, (April 1968) pp 336-343 The authors investigated the relationship between case-hardening conditions and the bending fatigue strength of a gear tooth from the view points of the residual stress generated on the root fillet and the increase of the materials strength (hardness) by casehardening. The many results obtained from the experiment are summarised as: 1 By proper selection of case-hardening conditions, the endurance limit of a gear tooth can be raised by about 100% of that of an unhardened gear 2 The contribution of the residual compressive stress generated on the root fillet to the fatigue strength reaches 40-50% of the increment of the endurance limit by casehardening 3 There exists an optimal case thickness for the bending fatigue strength of casehardened gears and an excessively large case thickness causes a decrease in the endurance limit 4 A formula for the calculation of the endurance limit of a gear tooth is developed, assuming that the residual stress influences the fatigue strength of metals as mean stress, and diagrams of hardness against endurance limit under pulsating stress and of hardness against true breaking strength are. presented on the basis of the existing data. The values calculated according to this formula and the diagrams show a good agreement with the experimental results. (Tribology 1969, abstract 194) AZZAM,H.T. Friction and wear testing machines to evaluate tomorrow’s lubricants. Lubrication Engineering, Vol 24, No 8 (August 1968) pp 366 In the past, absolute answers to specific friction, wear and lubrication problems have not been readily available. The author suggests that increased awareness of the factors affecting friction and wear, combined with the sophistication of test machines, is making laboratory tests more meaningful. 76

TIUBOLOGY

February

1969

The paper contains a useful survey of the better-known test machines pointing out the advantages and disadvantages of each and giving information on cost and time involved. The problems of laboratory testing are discussed and the factors affecting lubricant performance are summarised. (25 figures, 2 tables, 12 references) (Tribology 1969, abstract 195) BERND, L. H. Survey of the theory of mechanical face seals?l~haracteristics of seals. Lubrication Engineering, Vol 24, No 9 (September 1968) A brief review is given of theory and approaches that have been used both to explain the function of face seals and to improve their design. The essential characteristics of a face seal are summarised. The performance and inherent limitation of a face seal are discussed in terms of the axial forces on the seal faces and the character of the lubrication between the mating faces.

corrosion prevention. The author recommends that greases should therefore be judged on wear and oxidation properties not acid number. (6 tables, 10 references) (Tribology 1969, abstract 198) BLOOM, P. Bearing survey--ball and roller bearings. Machine Design and Control, Vol 6 (July 1968) pp 40-56 This is a practical survey of bearings commercially available but without any precise design information. The article gtves a short history of rolling elements and covers the main types of bearing: deep-groove radial ball, angular-contact ball, duplex ball, self-aligning ball, cylindrical roller, flexible roller, needle roller, long roller, tapered roller, spherical roller, ballthrust, and roller thrust. The author also gives some hints on selection procedure, installation, lubrication, and failure. (14 figures, 1 table) (Tribology 1969, abstract 199)

Considerable exploratory work has been R. H.,RUSSELL, J. K. done over the oast decade. sourred bv Dennv’- E BROWN, An experimental machine tool for cutting experiments, showing that’hydrodynamic and high energy rate forming studies. pressure generation (including load bearing) International Journal of Machine Tool and inward pumping (reduced leakage) can Design and Research, Vol 8, No 2 (1968) take place in a seal. Definite approaches pp 73-82 involving different mechanisms have emergMost investigations of the mechanics of ed. The status is that the dominant mechametal cutting and forming have used standard nisms have not been fully studied, isolated, machine tools to provide the cutting or and reduced to useable, universal paraforming action. This paper describes a meters. Hence the conscious exploitation machine tool developed solely for research of these mechanisms to obtain improved purposes. The machine has a table which sealing lies largely ahead in most cases. can move along straight line guideways at (Tribology 1969, abstract 196) any speed in the range 1.4-ZOOOft/min. Energy for driving the machine is stored in a large flywheel and the drive is arranged BINDA,P.A. to provide a constant speed during a cut of Construction equipment l-lubrication 2ft length, with the cutting forces up to and maintenance. Lubrication (Texaco), 15001b. Forming operations with forces up Vol 54, No 3 (1968) pp 33-44 to 60001b can be carried out if some small The author gives a comprehensive review of speed drop is tolerated. (10 figures, 2 the lubrication of all heavy construction references) (Tribology 1969, abstract 200) equipment. As the equipment represents a large capital investment it is wise to obtain maximum machine life in order to recoup CASTELLI, V., PIRVICS, J. this investment. The article includes a Review of numerical methods in gasbrief review of the management operation bearing film analysis. The Transactions and maintenance of this equipment before of the American Society of Mechanical enlarging upon the fuels and lubricants deEngineers, Journal of Lubrication Techsigned especially for them. Copious illunology, Vol 90, Series F, No 4 (1968) strations are included but there is a paucity pp Ill-792 of facts. This defect appears to be remedied The application of numerical methods to gas in the second part of the article in No 4 of bearing problems is of great importance this publication. (21 figures, 10 references) because of the difficulties encountered by (Tribology 1969, abstract 19’7) purely analytical methods in dealing with the nonlinear character of the governing equations. The equations and boundary conditions BISH,J.M. involved are stated and both analyticalThe effect of acidity and basicity of lubnumerical and direct-numerical solutions ricating greases upon their performance. are given. A most formidable amount of National Lubrication Grease Institute information is presented and the paper Spokesman, Vol 32, No 6 (September 1968) should serve as a useful reference for anypp 193-199 one working in the field. (4 figures, 35 refeWhen writing specifications for grease the rences) (Tribology 1969, abstract 201) problem always arises whether or not to include a neutralisation number requirement and U SO what limit to put on that requirement. Low acid numbers are often quoted in specifications but when these are exceeded it does not always follow that lubrication and corrosion properties are impaired. The paper describes work on eight commercial greases with a wide range of properties and compositions. Acidity (determined by five methods), oxidation stability, and wear tests were carried out. The five methods used to determine acidity give a wide variation in the acid and base numbers of some greases. A high acid number does not necessarily indicate a poor grease. Many additives will cause a considerable increase in the acid number but will also improve the antiwear, oxidation stability and/or

DEVINE, M. J., CERINI, J. P., CHAPPELL, W. H., SOULEN, J. R. New sulpbide addition agents for lubricant methods. Transactions of the American Society of Lubrication Engineers, Vol 2, No 4 (October 1968) pp 283-289 Two sulphides, AsSbS, and AsAsS,, prepared by aqueous precipitation, were examined as chemical additives for diester lubricating greases and organic resin solid film lubricants. The lubricant characteristics were studied and compared with AsaS,, AsaSS, SbaSa and SbaS,. Details are given of the preparation of the lubricants and anti-wear, copper corrosion and consistency tests were carried out on them. The most significant rSSUlt is the dual response of AsSbS,