Novel Experimental Set-Up to Investigate the Wear of Coatings for Sheet Metal Forming Tools

The use of Physical Vapour Deposition (PVD) and Chemical Vapour Deposition (CVD) coatings has increased significantly thanks to the improved tribological performances they offer in many metalforming processes. Nevertheless the proper coating selection for a specific forming operation is not well established yet, being mainly based on trails and error approaches. The use of FEM-supported analyses may represent an effective support in the optimization of process parameters, but the need of testing procedures and reliable models to describe the mechanical and tribological phenomena at the interface between the dies and the workpiece is still significant. The paper presents a novel experimental set-up for the evaluation of the wear resistance of coated dies in sheet metal forming operations. A progressive stamping process was taken as reference case and analysed by numerical simulation in order to evaluate contact pressures and sliding speed at tools-blank interface. A Diamond-Like-Carbon coating (Ti-DLC) was chosen as reference and deposited by PVD magnetron sputtering technique. The novel set up was designed and tested by using the parameters obtained from the numerical simulation. The results showed a good correlation with tribological and mechanical stresses applied on the reference industrial case, allowing the evaluation of the coating performances.