Blackening of MIM Parts

While plating small parts for a client, EPi's lab discovered a solution to blackening MIM parts. A solution that provides long lasting, durable, and estetically pleasing black finish of a MIM part. 

Metal injection molding (MIM) is the process of solid metal parts employing the injection molding technology.  The process is also know as powder injection molding (PIM).  MIM imposes few restrictions on the part design, produceses less waste and scrap, is less expensive than machining. MIM can be performed on a wide range od metals.  Although, the process gives a good finish, the finish can be further enhanced.  And  that is where we at EPi come in.

While blackening parts made of MIM alloy, such as 4605, containing iron, molybdenum, carbon, silica, chrome, nickel and tungsten elements we noticed that using the traditional black oxide chemistry for steel blackens the parts with a reddish mahogany color. Due to the nature of the MIM manufacturing process, parts experience different amounts of pressure in the mold, leading to differing hardness within the parts. In some cases, the MIM parts are also heat treated to obtain harder properties and other characteristics.  Therefore, we decided to try our Ultra-Blak 404L product. The results were unbelivable - true black finish. There were no color changes detected after using Ultra-Blak 404L product on the parts.