Development and Application of Micro-metal Injection Molding (μ-MIM) Process for Mass Production of Complex Micro Parts

With the widespread trend in industry towards greater miniaturization, precision metal micro-parts are gaining importance. The successful fabrication and operation of micro-components provide opportunity to produce miniaturized machines and mechanical systems. Further commercialization of the microsystem technology requires cost effective microfabrication methods for mass production of micro-metal parts. Micro-metal injection molding (μ-MIM) is considered a promising process for high-volume, low-cost production of micro components especially with complex geometries. However, there are some limitations to apply conventional MIM feedstock to μ-MIM, such as incomplete filling of die cavity, powder-binder separation, insufficient demolding strength, low sintering density and dimension instability. In this paper, the development of new binder system and feedstock formulation with micro-sized 17-4PH stainless steel powders, optimization of injection molding, debinding and sintering steps to achieve stable geometry, dimension and microstructure is reported. The capability of μ-MIM is demonstrated by manufacturing of high precision micro-gears and micro-hinge capture products.