Frictional characteristics of steel sheets used in automotive industry

In this paper the results of experimental tests aimed to determine the friction coefficient in sheet metal forming operations for various sheet metal materials and at different operative conditions are presented. The research has considered the frictional characterization of three kinds of drawing quality steels that are commonly used in automotive industry. These are a drawing quality steel (DQ), a deep drawing quality steel (DDQ), and extra deep drawing quality steel (EDDQ). For measurement of the sheet surface topography, a 3D stylus instrument Alicona InfiniteFocus was used. To determine the friction coefficient three tribological tests, i.e. a strip drawing test, a draw bead test and a pin-on-disc tribometer, have been conducted. The experimental results have ascertained several relationships showing the effect of sheet metal surface roughness, lubricant conditions and sheet orientation on the value of friction coefficient in sheet metal forming processes. The results further showed that the surface topography and sample orientation in the rolling direction of the sheet are significant factors that influence the friction coefficient. It was found that the tested steel sheets, selected from automotive industry applications, exhibit anisotropic resistance to the friction corresponding to the measured orientation in relation to the rolling direction of the sheet.