Thermal Contact Resistance Estimation: Influence of the Pressure Contact and the Coating Layer during a Hot Forming Process

The application of hot stamping in the automotive industry has experienced a fast growth due to the need for higher passive safety and weight reduction. Today, it is absolutely necessary to have reliable and accurate simulation predictions in order to assess the forming feasibility of a part as early as possible during the car design phase. In this paper, an original experimental procedure developed to estimate the thermal conductance at the Part Tools interfaces during a hot stamping process, is presented. The tools set (punch and die) have been designed to form samples with an omega shape. Two types of material have been stamped. the Usibor 1500P (R) and the 22MnB5 galvanized steel. The object is to describe correctly the thermal boundary conditions at the Part-Tools interfaces; the adopted procedure consists in estimating accurately the thermal contact resistance TCR at different contact points for different contact pressure values.