Effect of grain size on blank holder force of fine micro-blanking for Inconel 718 superalloy foils

Abstract. Regarding product miniaturization, there is a noticeable difference between micro-blanking and macro-blanking in terms of the quality of the parts and the metal deformation behavior. In this paper, fine micro-blanking simulations were conducted on Inconel 718 foils with a thickness of 100 μm and different grain size to investigate the effects of different blank holder force on the fracture length of blanking surface. The results showed that the empirical (macro) formula of blank holder cannot apply to fine micro-blanking. The fracture length gradually decreases with the increase of blank holder force. And as the grain growth, the blank holder force to obtain a micro-blanking surface with full burnish length and no fracture zone was smaller. Based on the effect of grain size and blank holder force, a revised empirical formula of blank holder force was established for fine micro-blanking. Then, the fine micro-blanking experiments of Inconel 718 superalloy foils were conducted to evaluate the feasibility for the revised empirical formula of blank holder force. This work may contribute to the selection of forming force for fine micro-blanking applications.