Development of 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 due to sliding friction between tool and work piece 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 performance are found to be consistent with qualitative evaluations by visual judgment of the resulting surface of the drawn cups. Hence, the quantitative method is found to enable a detailed ranking of lubricants performance.