Thermoelectric currents and their impact on wear behavior of punches during embossing operations

Abstract

The profitability of forming processes strongly depends on tool life. On this account, the main goal is to minimize tool wear. During forming operations, the four main wear mechanisms adhesion, abrasion, tribochemical reaction and surface breakdown appear. Abrasion and surface breakdown depend on the stress conditions and normally occur after several strokes. Adhesion and tribochemical reaction can appear right from the first stroke and are mainly triggered by temperature. Beside the known mechanic parameters influencing wear behavior like the die clearance, there are other aspects insufficiently examined. Thermoelectric currents and voltages occur in every forming tool and their influence on wear behavior has already been proven in the field of machining. However, there are no investigations on these currents and their impact on wear behavior in a forming tool. In this report, thermoelectric currents during lubricated and dry embossing respectively blanking operations were measured. Furthermore, their impact on adhesion and tribochemical reaction was examined.