Metal injection molding (MIM) is a metalworking process in which finely-powdered metal is mixed with a binder material to create a “feedstock” that is then shaped and solidified using injection molding. The molding process allows high volume, complex parts to be shaped in a single step. After molding, the part undergoes conditioning operations to remove the binder (debinding) and densify the powders. Finished products are small components used in many industries and applications.
The behavior of MIM feedstock is governed by rheology, the study of sludges, suspensions, and other non-Newtonian fluids.
Due to current equipment limitations, products must be molded using quantities of 100 grams or less per “shot” into the mold. This shot can be distributed into multiple cavities, making MIM cost-effective for small, intricate, high-volume products, which would otherwise be expensive to produce. MIM feedstock can be composed of a plethora of metals, but most common are stainless steels, widely used in powder metallurgy. After the initial molding, the feedstock binder is removed, and the metal particles are diffusion bonded and densified to achieve the desired strength properties. The latter operation typically shrinks the product by 15% in each dimension.
Powder metallurgy (PM) is a term covering a wide range of ways in which materials or components are made from metal powders. Powered mental is used to create many of the other materials we use at Tecton. PM processes can avoid, or greatly reduce, the need to use metal removal processes, thereby drastically reducing yield losses in the manufacture and often resulting in lower costs.
Powder metallurgy is also used to make unique materials impossible to get from melting or forming in other ways. A very important product of this type is tungsten carbide (WC). WC is used to cut and form other metals and is made from WC particles bonded with cobalt. It is very widely used in industry for tools of many types and globally ~50,000t/yr is made by PM. Other products include sintered filters, porous oil-impregnated bearings, electrical contacts and diamond tools.
Since the advent of industrial production–scale metal powder-based additive manufacturing (AM) in the 2010s, selective laser sintering and other metal AM processes are a new category of commercially important powder metallurgy applications.
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