Self-aligning micro punch-die tool-system for high precision blanking of thin metal foils

Abstract:
In this paper we present a novel approach of self-aligning system to align monocrystalline silicon micro-punches centrically to corresponding openings in the die with punch to die clearance of less than 2micrometer. The centricity of the punch to the die is very important for the longer life time of the tool and high quality of the punched workpiece. In case of micropunching, the punch to die clearance lies in the range of few µm depending on the thickness of the workpiece and it becomes really difficult to align the punch centrically to the die by conventional methods like using CCD cameras etc. In this paper we report the self-aligning system by means of dedicated guiding elements, which are etched near to the punches with a larger height than the punch using a two-step anisotropic etching process and then using it as mold to fabricated the die by using electroforming of Nickel-Cobalt alloy. The fabricated die is separated from the parent silicon mold by etching away silicon in KOH solution. The punch-die The guiding elements being taller than punch are first guided in to their respective die holes which eventually results in eccentric alignment of the punch into the die.