A quantitative lubricant test for deep drawing

A tribological test for deep drawing has been developed by which the performance of lubricants may be evaluated quantitatively measuring the maximum backstroke force on the punch owing to friction between tool and workpiece surface. The forming force is found not to give useful information regarding the lubricant performance, since it is not sensitive enough to reveal changes in the frictional contact, whereas the backstroke force is very sensitive to pick-up and galling even on micro-scale. Results from testing different lubricants with different performances are found to be consistent with visual judgement of the resulting surface of the drawn cups.