step twist drill bit

DIN338 twist drill, hss twist drill, DIN 338 hss twist drill, DIN345 twist drill, DIN340 drill bit, HSS drill bit 8mm.

The twist drill is the most common type of drill. The shank of the drill is held by the machine tool, which in turn imparts a rotary motion. This shank may be straight or tapered. The body of the drill is typically made up of two spiral grooves known as flutes, which are defined by a helix angle that is generally about 30 degree  but can vary depending on the material properties of the work piece. The point of the drill generally form a 118° angle and includes a 10 degree clearance angle and chisel edge .The chisel edge is flat with web thickness of approximately 0.015 x drill diameter. This edge can cause problems in hole location owing to its ability to "walk" on a surface before engaging the work piece. In the case of brittle materials, drill point angles of less than 118 are used, while ductile materials use larger points angles and smaller clearance angles.

Favorite of both the DIY and industrial markets. The general purpose, 118 degree point, ideal for portable and machine drilling. Designed to perform in low and medium carbon steel, cast iron and wood. The 135 degree split point is self-centering and reduces thrust. Ideal for portable or machine drilling of low tensile strength alloy material, stainless steel, and other medium duty applications. Available in bright finish, black oxide, titanium nitride coated, bronze color oxide. More choices for consumer.