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Predicting elastomer—fluid compatibility for hydraulic systems
LITERATURE
AND
vided. Autoradiographic and radiometric analyses were successful in determining the spatial distribution and the bleedout rates of impregnated oil in the various separators. This information is being utilized in the development and evaluation of new separator materials. Lubricant Evaluation for Bearing Systems Operating in Spatial Environments. P. Lewis et al., ASLE Trans., 6 (I) (1963) 6779; 14 figs., 4 tables, 7 refs. This paper presents a general summary of the results of several programs which were directed toward the selection of lubricants for rolling contact bearings operating in a spatial environment. The test procedures and results of evaporation tests on various lubricants and greases are described. In some of these tests, the effect of combined exposure to vacuum and radiation was determined. The problem of accelerating the tests in order to simulate long time exposure to spatial conditions was approached by using higher test temperatures to hasten evaporation. Several soft metal films and one plastic coating were evaluated as solid lubricants in instrument size bearings running at 3000 r.p.m. The results are summarized.
CURRENT
EVENTS
Predicting
335
Elastomer-Fluid
Compatibility
for Hydraulic Systems. A. Beerbower et al., ASLE Trans., 6 (I) (1963) 80-88; 5 figs., 3 tables, Ig refs. The elastomers used in sealing hydraulic and similar systems are frequently swollen or shrunk by prolonged contact with the fluids. The fundamental properties, especially the Hildebrand Solubility Parameter, of the fluid and elastomer components are related to these tendencies. Basically, the Solubility Parameter concept has been used to predict suitable elastomeric sealing materials for various fluids by avoiding close matches in solubility parameter. The present studies have shown that: (a) copolymer performance cannot always be predicted by averaging the properties of the homopolymers; (b) mixtures of solvents may not behave like an imaginary single fluid of average properties; and (c) chemical interactions, hydrogen bonding, and molecular shape factors introduce major complications. New correlations are proposed to enable the hydraulic engineer to obtain Solubility Parameters from the more common properties of heavy petroleum fractions.
7. SURFACE TREATMENT (no abstracts) 8. MACHINING AND TOOL WEAR Two Years of Finish-turning Research at the Technological University, Delft. H. J. Lambert, CIRP-Annalen, IO (4) (1961/
62) 24C-255; 25 figs., II refs. For many years the problem of finish-turning has been very real. The fact that the surfaces obtained are inferior to those predicted by theory is disconcerting. These poor results are due to the formation of grooves in the clearance face of the tool. The properties of these grooves were thoroughly studied, and several causes of groove formation were found. After stabilization, the left flank of the grooves always had the same direction as that of the chip flow. With this fact as a starting point, a basic study of the mechanism of chip formation was made. Factors determining stabilization were discovered.
It was shown that when the left flank of the groove had the same direction as that of the chip flow, the left flank was sheltered by the shear plane and was no longer exposed to the causes of wear, which are due to groove formation. This explained the mechanism of groove formation. Although no absolute remedy could be found, this explanation pointed to some ways of decreasing groove formation. In the first placelit) should) be possible to decrease the angle between chip flow and work-piece centre-line. It was also shown that, when an axial vibration was imposed, groove formation could be suppressed. The amplitude of the vibration has for this purpose to be greater than half the feed. With this arrangement remarkably good results were obtained.
Wear> 6 (‘963)
330-335
AND
vided. Autoradiographic and radiometric analyses were successful in determining the spatial distribution and the bleedout rates of impregnated oil in the various separators. This information is being utilized in the development and evaluation of new separator materials. Lubricant Evaluation for Bearing Systems Operating in Spatial Environments. P. Lewis et al., ASLE Trans., 6 (I) (1963) 6779; 14 figs., 4 tables, 7 refs. This paper presents a general summary of the results of several programs which were directed toward the selection of lubricants for rolling contact bearings operating in a spatial environment. The test procedures and results of evaporation tests on various lubricants and greases are described. In some of these tests, the effect of combined exposure to vacuum and radiation was determined. The problem of accelerating the tests in order to simulate long time exposure to spatial conditions was approached by using higher test temperatures to hasten evaporation. Several soft metal films and one plastic coating were evaluated as solid lubricants in instrument size bearings running at 3000 r.p.m. The results are summarized.
CURRENT
EVENTS
Predicting
335
Elastomer-Fluid
Compatibility
for Hydraulic Systems. A. Beerbower et al., ASLE Trans., 6 (I) (1963) 80-88; 5 figs., 3 tables, Ig refs. The elastomers used in sealing hydraulic and similar systems are frequently swollen or shrunk by prolonged contact with the fluids. The fundamental properties, especially the Hildebrand Solubility Parameter, of the fluid and elastomer components are related to these tendencies. Basically, the Solubility Parameter concept has been used to predict suitable elastomeric sealing materials for various fluids by avoiding close matches in solubility parameter. The present studies have shown that: (a) copolymer performance cannot always be predicted by averaging the properties of the homopolymers; (b) mixtures of solvents may not behave like an imaginary single fluid of average properties; and (c) chemical interactions, hydrogen bonding, and molecular shape factors introduce major complications. New correlations are proposed to enable the hydraulic engineer to obtain Solubility Parameters from the more common properties of heavy petroleum fractions.
7. SURFACE TREATMENT (no abstracts) 8. MACHINING AND TOOL WEAR Two Years of Finish-turning Research at the Technological University, Delft. H. J. Lambert, CIRP-Annalen, IO (4) (1961/
62) 24C-255; 25 figs., II refs. For many years the problem of finish-turning has been very real. The fact that the surfaces obtained are inferior to those predicted by theory is disconcerting. These poor results are due to the formation of grooves in the clearance face of the tool. The properties of these grooves were thoroughly studied, and several causes of groove formation were found. After stabilization, the left flank of the grooves always had the same direction as that of the chip flow. With this fact as a starting point, a basic study of the mechanism of chip formation was made. Factors determining stabilization were discovered.
It was shown that when the left flank of the groove had the same direction as that of the chip flow, the left flank was sheltered by the shear plane and was no longer exposed to the causes of wear, which are due to groove formation. This explained the mechanism of groove formation. Although no absolute remedy could be found, this explanation pointed to some ways of decreasing groove formation. In the first placelit) should) be possible to decrease the angle between chip flow and work-piece centre-line. It was also shown that, when an axial vibration was imposed, groove formation could be suppressed. The amplitude of the vibration has for this purpose to be greater than half the feed. With this arrangement remarkably good results were obtained.
Wear> 6 (‘963)
330-335