Friction measurement by the tip test for cold forging

► We made an attempt to reduce the friction in the compression test. ► K and n values AL6061-O and 2024-O were dropped by 10.7% and 14.3%, and 7.5% and 20.8%, respectively. ► Shear friction factors were calibrated with the newly measured flow stress. ► A non-dimensional equation describing shear friction factor as a function of the non-dimensional tip distance was derived based on the tip test results available in the literature.