THE INFLUENCE OF THE STRAIN RATE ON THE VALUE OF FRICTION COEFFICIENT

The Male and Cockroft ring compression test stands as one of the methods utilized to determine the coefficient of friction in forming processes. This approach eliminates the need for force measurement. This study presents the outcomes of the Male and Cockroft ring compression test conducted on Hardox 450 material at varying strain rates, conducted without lubricant. The experiments were carried out using a ZD 40 hydraulic press, CFA-80 pneumatic die hammer and split Hopkinson pressure bar test at the Faculty of Mechanical Engineering of Brno University of Technology. The test results were documented on a calibration diagram, revealing a significant influence of strain rate on the coefficient of friction. Specifically, the findings indicate that as the strain rate increases, the coefficient of friction decreases.