... over 20 years in producing internal; cylindrical; centerless; high precision; cnc grinding machine(spare parts).Our machies mainly apply for: inner ... parts, shot shoot, ceramic and optical parts. MK215 is a CNC internal grinding machine with excellent grinding performance and perfect after ... (mm)0.002cylindricity(mm)0.002surface roughnessRa0.32 YiJi CNC internal grinding machine for metal (MK215)