Frictional mechanisms in mixed lubricated regime in steel sheet metal forming

The friction is of critical importance to sheet metal forming operations. It affects the flow of material in the tool and thereby the scrap rate and final quality of products. In the experimental work the frictional response was measured in a bending under tension (BUT) test under mixed lubricated conditions. The study includes stainless steel, but previous research on carbon steels, coated and uncoated, are discussed also. The experimental results could be explained by the theory of pad bearings. The frictional response showed a correlation to the surface topography, e.g. the amplitude parameter (Sq) and texture aspect ratio parameter (Str). When predicting the frictional response of surfaces with multi-component distributions, the standard deviation of the distribution above the mean line could be used.