Evaluation of friction using cylinder compression test: two novel approaches based on the barreling deformation and forging force

Abstract

In this paper, two novel and simple approaches are presented for the evaluation of friction in the metal forming processed. By employing the data obtained from a cylinder compression test in addition to the flow curve, the friction coefficient of the process can also be evaluated. Hence, no extra measurement is required. Two new exponential parameters are introduced, geometrical and force barreling factors which are defined based on the change in geometry and forging force of the deformed cylinder, respectively. Numerical simulations are carried out to determine friction calibration curve diagram of cylindrical samples under various friction conditions. Then, by plotting the experimental data on the calibration curve diagram, the coefficient of friction of the process is determined. The results of the friction coefficients obtained from the geometrical and force barreling approaches are the same. The conventional ring compression tests are also performed for the corresponding lubricants to validate the proposed approaches. It is observed that the friction coefficients predicted by the presented approaches are identical to those obtained from the ring compression test. Also, friction coefficients that are greater than 0.2 can be determined more precisely than the ring compression test due to the increase in the distance of the curves.

Keywords

• friction
• cylinder compression test
• barreling factor
• bulk metal forming