History of MIM and Future Trend
MIM can be traced back to the earliest MIM preparation of ceramic spark plug in 1920s。In the following decades, powder injection molding mainly focuses on ceramic injection molding. Powder injection molding gradually transformed to metal injection molding oriented until 1979 Parmatech established by Wiech achieved two awards for MIM products, and Wiech and Rivers acquired patents. MIM companies were set up one after another, after Parmatech transferred out several patents. In 1980, Wiech established Witec, however, it was acquired by Brunswich which entered into MIM industry in 1982. Subsequently, Brunswick registered subsidiaries like Omark,Remington and Rocky. In 1986, a Japanese company Nippon Seison brought in Witec technology.
Process Introduction of Powder Injection Molding
Injection mold is main process of MIM technology, which can be divided into the following important steps:
Before injection molding, set screw speed and pressure in the barrel, tightly close mold and contract ejectorbeam. In the during of injection, injection nozzle close to the runner, screw forward. At this moment, locking ring on the front of the screw is closed, in order to ensure feeding extruded from feed cylinder under pressure, filling mold cavity. When head of feed cylinder has enough feeding to inject into mold cavity, screw stops running.
MIM is main development direction of future powder metallurgy technology
Metal injection molding is a new powder metallurgy near net forming technology through modern plastic injection molding technology.its basic processing is: mixing up metal porder and organic binder and form feeding,in the heating and plasticizing state（～150℃）, puting feed to mould cavity in injection machines to get the green parts, consider the green parts have plastic,we used chemically or pyrolysed way to remove 98% plastic get the brown parts, the finaly step is sintering to remove the rest of 2% plastic and get the sintered parts. Compare with traditional process, its process have high precision, good performance, low cost and etc characteristic