The MIM process has highly evolved since its first invented in the 1920’s but has only been a commercial viable method since the 1970’s, with equipment manufacturers, researchers, and engineers creating significant advancements. The process starts with the combination of metal powders and a polymer binder, creating a feedstock for injection molding. Once introduced to the molding machine, the feedstock becomes viscous as the polymer binder is heated in the barrel of the molding machine. The feedstock is then injected into molds similar to how plastic parts are formed, creating a “green” part. Since the binder system is only required for the molding process, it is removed from the part by thermally or solvent extraction. After debinding has been completed, the parts are sintered at very high temperatures in vacuum or continuous furnaces. During the sintering process the powders consolidate to form a solid metal part approaching 96-98% of full density of the original metal.
Metal injection molding (MIM) is a hybrid technology which integrates the shaping capability of plastic injection molding and the flexibility of conventional powder metallurgy. MIM is preferred for mass manufacturing of small, intricate geometric components of a variety of materials as it can achieve 95% to 98% of its wrought materials properties at significantly lower costs. Metal Injection Moulding MIM is a recently developed process which has become refined by Castem. It enable metals component to be produced in a manner with which plastic parts have been produced. This is accomplished by combining ultra-fine metal powders and a polymer binder to create a feedstock suitable for injection molding. The polymer binders are later removed and the remaining metal powders are sintered (the process of coalescing a powdered material into a solid or porous mass by means of heating without liquefaction) to achieve final parts. MIM able to produce parts with complex geometries, low part mass, and medium to high production volumes. Because it is a molding process, MIM offers value in design flexibility that is often too expensive to achieve by machining.