Metal injection moulding, a near-net-shape forming process for metal parts, includes the combination of ultra-fine metal powder and polymer binder system to produce materials that suitable for injection moulding. The polymer binder is then removed and sinter the remaining metal powder to obtain the final part with needed geometry and material chemical properties. MIM is suitable for parts with complex geometry and high production. MIM’s value is in terms of design flexibility, which is often too expensive to be got by machining.

After decades of elaborate design, excellent equipment manufacturers, researchers and engineers have made significant progress in the process. Starting from the combination of metal powder and polymer binder, MIM provides raw materials for injection moulding. In the moulding machine, the raw material becomes sticky, when the polymer binder is heated in the moulding barrel. Then the raw material is injected into the mould, which is similar to the formation of plastic parts. Since the adhesive system is only used in the forming process, it needs to be removed from the parts. This can be achieved by heat treatment or solvent extraction. After degreasing, the parts are sintered in vacuum or continuous furnace at very high temperature about 1600°. During sintering, the parts density can reach 96-98%.