MIM Design Principles
Component Surface Finish
If a matte surface finish is acceptable (approximately 32 RMS can be achieved through standard processes), then MIM requires no secondary polishing after sintering. This is a significant cost benefit over other production technologies. Lustrous surface finishes are possible by polishing. The time required to achieve a high polish is shorter for MIM versus casting. Thus, high polish conditions are possible. The surface finish advantage with MIM is two-fold. First, the time is shortened by the small amount of material removed after sintering. But more significant, especially in areas of great aesthetic concern, jewelry, watches, computer logos, designer eyeglasses, and designer luggage, is the fact that no subsurface pores are exposed in MIM. This is not the case in casting, where larger residual pores can lie just below the surface and are opened in polishing, making the component useless.