Metal injection molding (MIM) is a process in which finely powdered metal is mixed with binder material to create a solidified feedstock and shaped using injection molding. The molding process allows high volume of high-density complex parts to be shaped in a single step. The metal injection molding MIM parts process is used to fabricate complex parts economically in structural metals; it can provide a significant cost saving to the manufacturers and reduce parts per cost.
The MIM process starts with mixing the feedstock, which is basically a combination of metal powder and binder. The binder is material, which is a mixture of plastic and wax materials that melt and hold the metal particles in position while the stock flows in the mold cavity. The feedstock is heated into a mold cavity. Then parts are removed from the mold, and these parts are the shape of the final parts.
The next step is called debinding; this removes almost all the binders from the parts by heating it or by chemically removing it with solvents. After that you will have the parts which only contain 40% to 30% of the binder in it, which is good because it is used to help the parts maintain their shape and form.
Furnace the parts
The final step is to furnace the parts by placing them on the ceramic tray and then placing them in a furnace to remove the last of the binder and sinter the parts. The temperature of the furnace rises until the metal particles reach 90% of their melting temperature, at which they join together. After that, the parts end up at 95% to 98% percent of full density and have a smooth surface finish.