A Tensile Strip Test for Evaluating Friction in Sheet Metal Forming

A tensile strip test has been developed for evaluating friction under conditions which simulate the stretching of sheet over the punch corner radius in forming a shallow stamping in a typical draw die. Preliminary results are presented for the aluminum alloys 5182-0, 2036-T4, 6009-T4 and 6010-T4,which are used for automotive applications. Tests were conducted with various lubrication conditions, different corner radii and with prestrained sheet. For given friction conditions, the maximum strain obtained over the face of the punch was significantly affected by small amounts of prestrain or small changes in the tensile/yield ratio of the sheet.