the mold surface roughness is a very important technical parameter in mold making, because the surface finish of the molding area directly affects the surface roughness of the plastic part. A range of polishing tools is used to meet a different surface finish requirement. The society of plastics industry classifies mold surface finishes into 12 grades in 4 categories:

A—mirror image, it is typically polished with diamond paste, it’s surface finish Ra is 0—0.0001mm, applicable for plastic parts whose surface should have high luster. In general, mirror image is further classified into A1, A2, and A3.

B—smooth, it is usually polished with sand paper. It’s surface finish is between 0.0001—0.0002mm, applicable for plastic parts with a typical surface requirement. This category can be further classified into B1, B2, and B3.

C— is polished with whetstone. It’s surface finish is between 0.0002—0.0008mm, applicable for plastic parts without a specific surface finish requirement. This category is also further classified into C1, C2, and C3.

D—General. Sand blasting is commonly used. This category is also further classified into D1, D2, and D3.