Coefficient of Friction Determination


Our lab has the capability to determine the coefficients of friction under various forming modes.  The following tests are usually used to determine the interface friction behaviors between sheet metal and die/tool:

• Ninety Degree Bending - During the test, sheet metal is drawn over a die radius with controlled back tension (restraint force).  The coefficient of friction can be calculated using this test.  Tests can be performed using different radii, speeds, back tensions, die materials and lubricants.  One special feature of this test is that it can heat the die radius (up to 400^oF) during testing to simulate the die's heating during production.
   
• Dome Test - This test simulates the sheet metal forming in the stretch mode.  The coefficient of friction is not available for this test.  This test can be used for a relative comparison among different materials and lubricants.
   
• Draw Bead Simulator - This test simulates the sheet metal drawn over a draw bead.  The coefficient of friction can be calculated using this test.  The test can be performed using different speeds, die radii and tool temperatures.
   
• Stretch Forming Simulator - This test simulates the sheet metal stretched over a tool surface (stretch forming).  The coefficient of friction can be calculated using this test, and the coefficient of friction may be changed with the amount of stretching.  The test can be performed using different speeds, speed profiles, radii and die materials.
   
• Strip Draw Test  - This test simulates the sheet metal moving in the relative flat die/punch surface.  The coefficient of friction can be calculated using this test. The test can be performed using different speeds, normal pressure and tool temperatures.