Why do similar parts processed identically achieve different surface finishes? The answer lies in the material.

This case compares two parts with similar polygonal inner profiles: one made of C45 steel, the other of A7075 aluminum. Due to design constraints, EDM was chosen over CNC machining. However, the softer aluminum resulted in a rougher surface (exceeding Ra0.8), as post-EDM polishing was unfeasible due to tight pre-machined hole tolerances. Adding fillets for CNC machining was also impractical per design requirements. After discussion, the client retained the polygonal design but adjusted the finish requirement to Ra3.2.

Material selection critically impacts EDM outcomes—let us help optimize your design for precision.