Physicochemical Analysis of Machine Hammer Peened Surface Structures for Deep Drawing: Determination of the Work of Adhesion and Spreading Pressure of Lubrication to Surface Structure

Increasing demands concerning the performance of tribological systems for metal forming due to ecological restrictions or increased process loads demand the development of innovative tribological solutions. In preliminary works, it could be shown that surface structures on deep drawing tools manufactured by the incremental forming process machine hammer peening (MHP) have the potential to reduce friction. The friction reduction can be observed in strip drawing when comparing different surface structures against a state-of-the-art reference. A subsequently conducted wear analysis showed an adhesive wear on the structures. This leads to the conclusion that the lubricant film breaks due to increased contact pressures. In order to optimize the wetting of the lubricant and to avoid film break-ups, the molecular interactions in terms of the work of adhesion and spreading pressure between lubricant and MHP tool surfaces are investigated from a physicochemical point of view in this research work. The investigation approach is based on the use of the drop shape analysis.