Temperature conditions during ‘cold’ sheet metal stamping

• Friction and deformation-induced heating during stamping of AHSS steel were examined.
• Frictional heating is primary cause of peak die temperatures.
• High temperature generated (up to 180 °C) during ambient production-type conditions.
• Excellent correlation between developed thermo-mechanical FE model and experiments.
• Process speed and blank material strength strongly influence maximum temperatures.

This paper investigates the friction and deformation-induced heating that occurs during the stamping of high strength sheet steels, under room temperature conditions. A thermo-mechanical finite element model of a typical plane strain stamping process was developed to understand the temperature conditions experienced within the die and blank material; and this was validated against experimental measurements. A high level of correlation was achieved between the finite element model and experimental data for a range of operating conditions and parameters. The model showed that the heat generated during realistic production conditions can result in high temperatures of up to 108 °C and 181 °C in the blank and die materials, respectively, for what was traditionally expected to be ‘cold’ forming conditions. It was identified that frictional heating was primarily responsible for the peak temperatures at the die surface, whilst the peak blank temperatures were caused by a combination of frictional and deformation induced heating. The results provide new insights into the local conditions within the blank and die, and are of direct relevance to sheet formability and tool wear performance during industrial stamping processes.