Injection molding of 316L stainless steel microstructures

Micro powder injection molding (muPIM) is a promising process for low cost fabrication of three-dimensional microstructures. The muPIM can be used for a wide range of metal and ceramic materials, combined with the potential for mass production. In this paper, initial study on the molding of 316L stainless steel microstructures was investigated. Three different micro-cavity shapes were used. Small powder with mean size of 4 mum was used with two multi-component binder systems. Microstructures with dimension as small as 35 mum could be injection molded. For successful molding, the binder system must provide high green strength to withstand ejection from the mold and suitable molding parameters used. For example, a high mold temperature is required and ejection speed must be reduced. The cross-sections of the microstructures are precisely replicated. The general shape in the depth direction is replicated although it is not as good as that for the cross-section. More work has to be conducted to realize the full potentials of the process.