Influence of the inaccuracy of thermal contact conductance coefficient on the weighted-mean temperature calculated for a forged blank

Modern software intended for the simulation of metal forging processes requires the use of a reliable database composed by physical parameters of materials. One of the most important and poorly studied parameter is the thermal contact conductance coefficient of the blank-die interface, which determines the thermal state of a blank in forging. The absence of information makes engineers use approximate or arbitrary values of the coefficient, without the possibility of estimating a simulation error. In this paper, a new approach to the calculation of the heat flux through the blank-die interface is shown. The values of thermal contact conductance coefficient which are typical for hot forging processes are given for the first time. The errors in determining of the weighted-mean temperature of a blank, caused by the inaccuracy of thermal contact conductance coefficient, are calculated. Some recommendations concerning the use of inaccurate values of this coefficient in the simulation are made.