PROFI 24-pcs. twist drill set DIN 338 HSS-R 1,0 - 10,5 mm + 3,3 / 4,2 / 6,8 / 10,2 mm

PROFI 24pcs. Twist drill set din338 HSS-R 1,0 - 10,5 + 3,3 / 4,2 / 6,8 / 10,2 mm

Description: HSS R twist drills are roll-rolled twist drills with a 118 degree point angle.
 

Tolerance class: h8 for the diameter

Surface: burnished and black

The 24-piece twist drill set has drills from 1.0 to 10.5 mm. These rise in 0.5 mm intervals.

Point angle
Twist drills have different cuts on the drill bit tip for different materials. The rule is a Kegelmantelanschliff with an angle of 118 degrees. It makes the drill insensitive to impact and lateral forces, because the main cutting edges are robust.

For harder materials, a larger tip angle makes sense. Typical here is a point angle of 135 degrees and a Kreuzanschliff. It reduces the contact pressure due to the smaller cutting length.

main cutting edge
The main cutting edge takes over the actual drilling process. They are formed by flutes or rake surfaces as well as the rear grinding surfaces. There are two main cutting edges on the twist drill. They are connected by a chisel edge.

crosscutting
In the middle of the drill bit is the chisel edge. This is also the line of contact of the two Hinterschliffflächen. By certain grinding methods, one can reduce the size of the cross cutting edge. For larger drills, this is done by the so-called Ausspitzen or by a Kreuzanschliff. Thus, the friction of the drill on the workpiece is reduced and facilitates the feed.

The transverse cutting edge may have a Kreunzanschliff (Form C) - also called split-point or a pointed cross-cutting edge (Form A). The main differences can be seen in the graphic.