Metal Injection Molding
Metal injection molding utilizes a metal and resin mixture to create molded metal products. In the industry it is referred to as MIM. There are four distinct steps in manufacturing MIM products: feed stock, molding, debinding, and sintering. The first step is creating the metal powder and resin feed stock. The metals that can be made into this feed stock are stainless steel, low alloy steel, copper, nickel, chrome, bronze, and tungsten. Second, the heated feed stock is injected into the mold. The resulting cast is referred to as a green mold. Third, green molds are placed in a debinding oven. This causes the resin or binding agent mixed in the feed stock to melt away. The resulting cast is called a brown part. The final step is called sintering. The fragile brown part is put into a sintering furnace where remaining binder is removed. The high heat specified to the metal’s melting point causes the brown part to shrink by about 20%. This is because the heating process binds the metal back together without any space from the binder while keeping the molded shape. This process produces detailed metal parts that cannot be cast in traditional metal working. A few examples of industries that use this molding process are automotive, computer component, aerospace, firearms and hardware.