Tool life prediction for the bolt forming process based on high-cycle fatigue and wear

In the present investigation an integrated model for predicting tool life in the cold forging process considering the high-cycle fatigue and wear is proposed in terms of mechanical properties of the workpiece. For calculating wear amount during cold forging, Archard's wear model was reformulated as an incremental form and implemented into the finite element code. Following a series of FE simulations, empirical equations for estimating the tool life based on wear and fatigue models were obtained. The present results showed that tool life due to high-cycle fatigue failure decreased significantly as the strength of material increased. Meanwhile tool life caused by wear also decreased as the strength of material decreased but the rate of tool life reduction was relatively small. This implies that tool life should be estimated using the fatigue failure model for cold forging of high strength steels. On the other hand, for cold forging of low strength steels, die life should be evaluated considering wear model as well.