Performance characteristics of spiral-grooved and shrouded Rayleigh step profiles for high-speed noncontacting gas seals

ABSTRACTS Copies of original arlicles aye besi oblained by turiling direct fo ihe jountal in which lhey appeared. The addresses o/jottntals can be found in Q re/evence book szcch as World Lisl o/ Sciettlific and Technical Publicalions, Willings Press Guide, and/or Amen’can jountals ouly. Ayers. AKHTER, M., WRIGHT, K. H. R. A field study of the wear of a planing bed plate. Wear, Vol 13, No 2 (1969) pp 85-89 Field tests to measure the wear of a grey cast-iron planing machme bed-plate caused by various timbers were done. A reference mark technique was used to measure wear. It is thought that bed-plate life could be improved by a factor of 10 to 100 if high chromium irons were used instead Of grey cast-iron. (4 figures, 4 references) (Tribology 1969, abstract 287) APPELDOORN, J. K., GOLDMAN, J. B., TAO, F. F. Corrosive wear by atmospheric oxygen and moisture. Transactions of the American Society of Lubrication Engineers, Vol 12, NO 2 (April 1969) pp 140-150 Oxygen and moisture are shown to cause a significant increase in friction and wear in non-scuffing conditions. In certain cases wear in humid air is destructive, but can be entirely eliminated by blanketing the system in dry nitrogen. The authors suggest that this pro-wear effect of air is entirely reversible, that it occurs with most metallurgies and lubricant types, and that it may be controlled by incorporating suitable additives in the oil. Various wear mechanisms have been examined to explain the experimental results; the most satisfactory is a simple corrosive wear phenomenom involving the formulation and rubbing away of metal oxides. (11 figures, 7 tables, 26 references) (Tribology 1969, abstract 288) ARMSTRONG, E. L., LINDEMAN, M. A. Effects of oil viscosity and soap type on torque in a grease-lubricated journal bearing. National Lubricating Grease Institute Spokesman, Vol 33, No 4 (July 1969) pp 152-159 An earlier paper (July 1968 Spokesman) described an apparatus for torque measurement in a journal bearing lin diameter by lin length operating from l-5000rev/min with loads up to 2001b. Typical curves of torque against time, torque against load, and torque against speed were illustrated. This present paper includes additional test data to show the repeatability of the test procedure and the effects of oil viscosity, soap type, NLGI grade, and journal finish on torque. Running-torque measurements were made at 1200rev/ min and 1201b radial load. Static coefficient of friction measurements were made at 1201b load. (5 figures, 8 tables) (Tribology 1969, abstract 289) BMTIAN, E. Lt. H. Modern developments in fluids and metal forming operations. Lubrication Engineering, Vol 25, No 7 (1969) pp 278-284 This is a review article of modern metal forming operations. The use of propellants and gaseous explosives, pneumatic systems, electro-hydraulic, magnetic, hydrostatic, and ultrasonic techniques in metal forming have introduced new requirements for lubricants used in these processes. Forming of exotic metals has also made new demands for unusual lubricants. (2 tables, 52 references) (Tribology 1969, abstract 290) BLACK, A. L., DUNSTER, R. W. Comparative study of surface deposits and hehaviour of MoS, particles and molybdenum diaUyl-dithiophosphate. Wear, Vol 13, No 2 (1969) pp 119-132 The lubricating properties of suspensions of MoS, particles and solutions of molybdenum dialkyl-dithio-phosphate (mddp) and zinc dialkyl-dithio-phosphate (zddp) were compared on a Falex lubrication tester and a cam and follower rig. The

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BY PAMELA

POCGCK AND A. D. JORDAN

rates of wear in the cam system of MoS, suspensions with or without a dispersant were about half those of mddp. The load capacity of MoS, suspensions was better than mddp or zddp but at low loads mddp had the best overall performance. It was concluded that solid lubricants in oil suspensions can carry loads equal or greater than the films formed by oilsoluble ep additives. (8 figures, 7 tables, 9 references) (Tribology 1969, abstract 291) CHENG, H. S., CASTELLI, V., CHOW, C. Y. Performance characteristics of spiral-grooved and shrouded Rayleigh step profiles for high-speed noncontacting gas seals. Transactions of the American Society of Mechanical Engineers, Journal of Lubrication Technology, Vol 91, Series F, No 1 (January 1969) pp 60-68 Current methods in gas lubrication have been used in this paper to analyse the gas film characteristics in a highspeed, face-type gas seal. Detailed analyses are presented for two different surface geometries, the spiral-grooveorifice seal and the shrouded Rayleigh step seal. The results are presented in three parts. The first part shows the performance of a spiral-groove seal without the orifices, and also the difference in performance when the grooves are located at the high pressure, low pressure, or both sides. The second part gives typical performance on a non parallel film profile for the spiral-groove-orifice seal as well as for the shrouded Rayleigh step seal. In the last part, a comparison is made between the two seal geometries on their. tolerance to coning or dishing under a constant seal load. (21 figures, 7 references) (Tribology 1969, abstract 292) CHIU, Y. P., TALLIAN, T. E., McCGOL, J. I., MARTIN, J. A. A mathematical model of spalUng fatigue failure in rolling contact. Transactions of the American Society of Lubrication Engineers, Vol 12, No 2 (April 1969) pp 106-116 The authors identify variables which affect the fatigue life of a rolling contact and present a mathematical model of subsurface and surface crack propagation. The ‘life to failure’ of volume elements in the vicinity of a defect (the defect life) is formulated. The model is the result of the authors’ re-evaluation of the Lundberg-Palmgren premises for the prediction of rolling bearing (fatigue) life. It is characterized by the inclusion of bulk material parameters, defect characteristics and parameters of geometry, stress, lubrication and surface topography. A statistical expression for the life of an entire rolling body is based on the defect life formula. The LundbergPalmgren formulas appear as a special case of the new expressions. (24 references) (Tribology 1969, abstract 293) CLERICO, M. A study of the friction and wear of nylon against metal. Wear, Vol 13, No 3 (1969) pp 183-197 Friction and wear tests over several thousand hours were done with nylon and metal specimens. It was shown that wear is greater when tests are interrupted, because fresh ‘running-in’ occurs on each restart. With steel, bronze and copper adhesive wear of nylon occurs by forming a layer which adhers tightly to the metal. The frictfon coefficient decreases with the formation of this layer. (11 figures, 3 tables, 10 references) (Tribology 1969, abstract 294) CGCKROFT, R. The glass lubricated extrusion of steel. Metals and Materials, Vol 3, No 9 (1969) pp 351-355 A review of extrusion processes is given and the advantages of glass lubrication are indicated. The main advantage is a low coefficient of friction at extrusion temperatures (about 1100°C). A comparison is made between extruding and casting and some typical dimensional tolerances available with extrusion are given. (7 figures, 2 tables, 4 references) (Tribology 1969, abstract 295) Tribology

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