Thursday, 5 January 2017

DRILLING Point Angle (2β)

The point angle is selected to suit the hardness and brittleness of the material being drilled.
Harder materials have higher point angles, soft materials have lower point angles.
An increase in the drill point angle leads to an increase in the thrust force and a decrease in the torque due to increase of the orthogonal rake angle.
This angle (half) refers to side cutting edge angle of a single point tool.
     Standard Point Angle is 118°
   It is 116° to 118° for medium hard steel and cast iron
It is 125° for hardened steel
    It is 130° to 140° for brass and bronze
It is only 60° for wood and plastics

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