chapter  9
24 Pages

Drilling techniques and drilling machines

The modern twist drill is made from a cylindrical blank by machining two helical grooves into it to form the flutes. The flutes run the full length of the body of the drill and have several functions:

• They provide the rake angle. • They form the cutting edge. • They provide a passage for any coolant/cutting lubricant. • They provide a passage for the swarf to leave the hole.