Minimizing Contamination in Commercial Mass Production of Metal Injection Molded Pure Titanium

Abstract

Metal injection molding (MIM) has been used in manufacturing highly complex metal parts but has had far less application for titanium which is a reactive metal. The implementation of titanium MIM on a mass production scale still raises many difficulties due to the contamination from processes, especially in case of manufacturing titanium parts on existing steel-based part production lines. The effects of material contamination in commercially-pure (CP) titanium parts have been studied and the trial production of titanium parts on a commercial MIM production line has been carried out. Steel-based feedstocks gathering on titanium green parts diffused into the titanium giving rise to liquid phase sintering, which disfigured the appearance of the titanium products. The trial production of titanium parts on a steel-based mass production line resulted in products with poor mechanical properties compared with those produced under laboratory conditions. The contamination by steel during the process resulted in the formation of a Ti–Fe solid solution phase at localized areas in the parts, decreasing the elongation to below 4%. Methods to reduce contamination in the mass production line have been carefully applied and acceptable properties, e.g., elongation about 18%, of titanium parts successfully achieved. CP titanium parts can be manufactured via well-controlled production in the steel-based MIM factory.