Metal injection molding is a technology that combines metal powder technology with capabilities of plastic injection molding. It allows complex shapes to be created by "reassembling" powder into a solid part through injection molding. Compounding of these metal powders with "binders" creates the feedstock. The binder selected is critical. Some would say that the binder is the critical factor in the successful production of MIM components. SMP has multiple binder systems available to best couple the appropriate technology to your application.

Once the feedstock is compounded it is ready for molding. These feedstocks process like most thermoplastic resins since at this stage only the polymer melts providing the fluid mechanics necessary to transfer the powdered material into the desired shape. A standard injection-molding machine is employed utilizing standard injection tooling. Once molded a part that contains both the binder and powder is termed a "green" part.

After creating the desired shape the binding materials are no longer needed. Depending on the binder system selected for the application different debinding technologies are required. The determining characteristics of binder selection play to the applications economics, tolerance requirements, and geometrical size of the part. SMP has the capability for all debinding technologies whether it is catalytic, thermal or solvent. During debinding the strength of the component decreases markedly and care must be taken to handle the now termed "brown" part.

Once a part has gone through its primary debind cycle the "brown" part which has had approximately 90% of its total binder content removed will transfer to sintering. The remaining organics (now providing the part with its structural integrity) will be removed thermally by elevating the temperature to around 600( C at which time the organics pyrolize and the structural integrity transfers to pre-sintering or interparticle welding.

When all of the binder system has been removed, the part enters the final stage called sintering. Sintering is the name given to the heating process in which the separate particles weld together and develop the final mechanical properties. These properties are not significantly, if at all, below those of wrought metal of the same composition. The ability of these powdered metal components to rival the properties of wrought materials is in part due to the high density of the final shape very closely approaching theoretical, or greater than 98%. During this process stage, the voids created by the binder removal close and the part shrinks up to 20% depending on the binder and base material of choice.

Our philosophy at SMP is to engineer novel solutions to your manufacturing requirements. While MIM components can be post processed by any variety of traditional methods (i.e. HIP, EDM, Polish, Mill, Grind, Coin, Coat, Weld etc.) we strive to deliver a net shape component ready for use. Over 90% of our components are manufactured this way by utilizing unique tooling and processing methods eliminating the need for costly secondary operations. When requirements exceed process capabilities we work with you to develop the most cost-effective solution.