WHAT IS METAL INJECTION MOLDING?

Metal injection molding (MIM) is a proven, innovative technology that offers the capability of mass producing complex-shaped metal parts consistently and reliably. It is used to manufacture products ranging from golf clubs and fuel injector nozzles to cell phone components and complex surgical tools. You’ll find MIM parts used in aerospace and defense, medical & dental, electronics, agriculture, automotive, and many other markets.

ADVANTAGES OF METAL INJECTION MOLDING

A few key advantages of the metal injection molding process include:

  • its capability to produce excellent mechanical properties, including properties not obtainable by other processing technologies;
  • the ability to produce high-precision components to net-shape;
  • nearly unlimited shape and geometric-feature capabilities;
  • high-production rates due to the efficiency of the processing equipment compared with other metal forming technologies;
  • the feedstock is re-useable if it is not processed after molding;
  • high-material utilization with minimal material loss.
Rack of MIM Parts

A BRIEF OVERVIEW

Injection Mold
  • The MIM process utilizes fine metal powders that are custom formulated with a binder into a feedstock which is granulated and then fed into a mold/tool cavity (or multiple cavities) of a conventional injection molding machine.
  • The molded or “green” part is then cooled and ejected from the mold.
  • Next the first stage binder is removed using a solvent, thermal furnace, or catalytic process. The resulting part is called a “brown” part and is in a porous state.
  • The remaining second stage binder is thermally removed during a debinding segment of the sintering process. This segment is normally a hold at a temperature in which the binder evaporates out of the part through the pores that were created by evacuating the first stage binder.
  • Next the parts in the furnace are ramped up to a sintering temperature to close the voids between the metal powder particles, thereby increasing the density of the part. The end-product metal has mechanical and physical properties similar to annealed parts made using conventional metalworking methods.

The MIM process is very similar to plastic injection molding and high-pressure die casting, and it can produce much the same shapes and configuration features. Metal injection molding is typically geared towards highly complex parts that otherwise would require extensive finish machining or assembly operations if made by any other metal-forming process, but can also produce simple parts as well, when cost effective. Additional processing enhancements include increased savings due to high material utilization, shorter manufacturing times, and a smaller manufacturing footprint.

WHERE CAN I FIND MIM?

Metal injection molded products are all around you. It’s used in:

  • the medical and dental markets for surgical tools, implants, etc.;
  • the automotive market (engine, transmission, and chassis applications);
  • the military and defense markets (firearms);
  • the aerospace market (engines);
  • the lawn and garden market;
  • the recreation and hand tools markets (golf club parts);
  • the off-highway and agricultural equipment markets;
  • and the lifestyle markets (watches, glasses, jewelry, etc.).

For working examples, please visit the case studies section of this website.