Comparisons of friction models in bulk metal forming

A friction model is one of the key input boundary conditions in finite element simulations. It is said that the friction model plays an important role in controlling the accuracy of necessary output results predicted. Among the various friction models, which one is of higher accuracy is still unknown and controversial. In this paper, finite element analyses applying five different friction models to experiments of upsetting of AA 6082 lubricated with four lubricants are presented. Frictional parameter values are determined by fitness of data of friction area ratio from finite element analyses to experimental results. It is found that calibration curves of the friction area ratio for all of the five chosen friction models used in the finite element simulations do fit the experimental results. Usually, calibration curves of the friction area ratio are more sensitive to friction at the tool/workpiece interface than those of the normal pressure.