Evaluation of Friction Behavior of Automotive Steels With Different Test Methods

Friction and lubrication play important roles in sheet metal forming operations. They affect the working force required to produce a particular deformation, strain distribution, product surface quality, tool life, etc. These, in turn, control the incident of cracking or tearing failures and dimensional variability due to tooling deflection and workpiece springback. Consequently, careful control of friction and lubrication is essential for a successful metal forming operation. Friction behavior has been found deviate from test method to test method. To understand the true friction behavior of automotive steels in different forming modes, the Stretch forming Simulator (SFS) has been developed and evaluated on seven different zinc coated sheet steels. The results were compared to the test data obtained from a bending under tension (BUT) test and a draw bead simulator (DBS) test. The dome height test and deep draw cup test were also used to verify the test results.