Performance improvement of hot stamping die for patchwork blank using mixed cooling channel designs with straight and conformal channels

•A mixed cooling channel (MCC) is proposed for patchwork blanks.•Performance comparison between conventional channels and MCC is conducted.•The optimum mass flow ratio in the MCC is determined to be 10%.•The MCC exhibits higher cooling performance than conventional channels.•The MCC exhibits a 5.8–9.0% greater daily production than conventional channels.