Why is the drill angle 118 degrees?
Standard angle has 118, 120, 130, 135, 140, processing material is different, drill top angle is not the same.
HSS high speed steel drill bit: vertex angle is generally 118 degrees, sometimes greater than 130 degrees, HM carbide drill bit: vertex angle is generally 140 degrees; straight groove drilling is often 130 degrees, three edge drill is generally 150 degrees.
It is the projection angle of the two main cutting edges in the middle section. The smaller the vertex angle is, the longer the main cutting edge is, the load on the cutting edge of the unit decreases, and the axial force decreases, which has a strong axial stability to the bit. And the knife edge at the outer circle is increased, which is beneficial to dissipate heat and improve the durability of the cutter.
