HSS Titanium Coated Twist Drill Bit Set

HSS Titanium Coated Twist Drill Bit 1.5-12mm Set A twist drill is a metal rod of a specific diameter that has two, three or four spiral flutes running most of its length. Two-flute drills are for primary drilling, whereas three- and four-flute drills are only for enlarging cast or punched holes in a production situation. The section between the two flutes is called the web, and a point is formed by relief grinding the web to an angle of 59° from the drill's axis, which is 118° inclusive. This forms a sloped cutting edge at the edge of the flute, which is called the lip. A twist drill is very inefficient at the point because the web leaves scant exit space for debris (called swarf) and because the point has a low surface speed compared to the periphery. For this reason, a good scheme for drilling larger holes is to first drill 1/4" or less and then follow with the drill of the desired diameter. Package & Shipping: Free shipping all over the world 13pcs Twist Drill Bit To Korea, Jap