EFFECTS OF DIE SURFACE-ROUGHNESS ON LUBRICATING CONDITIONS IN THE SHEET-METAL COMPRESSION-FRICTION TEST

This study shows the influence of die surface roughness on friction under mixed lubrication conditions where the oil film thickness is comparable with the die surface roughness and the die pressures are high enough to deform the workpiece plastically. Experimental results obtained with widely different die surface roughnesses and mean oil film thicknesses are consolidated in terms of relative or effective oil film thicknesses, and the additional effects of sliding speed and lubricant properties are clarified. Effect of the direction of sliding relative to that of the die surface finish (grinding direction) is also discussed.