Drill.

摘要

The drill pin has a cylindrical shape with a basic cutting surface (G) together with a straight swarf groove. The swarf groove, in the cross-section, reaches as far as the centre of the drill bit. The bit may be made of a hard metal and has a diameter of 3 mm and a groove length of 15 mm. At a r.p.m. of 4200/min and a speed of 1500 mm/min., an exact hole with no swarf on the edges can be achieved.