40 size is more common in high power, heavy duty and metal cutting applications. HSK 50 and HSK 63 tool holders provide better cutting accuracy and reliability. Their only disadvantage is higher cost than comparable ISO tool holders. Their popularity is growing rapidly due to performance. Keep tool tapers, shafts and collets scrupulously clean.
Minor contamination can cause tool misalignment, out of balance, tool slip and poor quality cuts.
Tool slip leads operators to overtighten collet nuts and damage theads. This minimizes condensation as well as contaminants being drawn into the bearing supports. Do not apply load to a cold electric spindle. This allows bearings, supports and shaft to reach their designed dimensions. Applying load to a cold spindle will cause premature failure of bearings.