Function of Tool Features for Face Milling

Lead Angle (KAPR) and Cutting Resistance

Lead Angle (KAPR) and Cutting Resistance

* Principal force : Force is in the opposite direction of face milling rotation.
* Back force : Force that pushes in the axial direction.
* Feed force : Force is in the feed direction and is caused by table feed.

  • Lead Angle 90°

Back force is in the minus direction. Lifts the work material when work material clamp rigidity is low.

  • Lead Angle 75°

Lead Angle 75° is recommended for face milling of work material with low rigidity such as thin work material.

  • Lead Angle 45°

The largest back force. Bends thin work material and lowers cutting accuracy.
*Prevents work material edge chipping in cast iron cutting.

Lead Angle and Tool Life

Lead Angle and Chip Thickness

When the depth of cut and feed per tooth, fz, are fixed, the larger lead angle (KAPR) is, then the thinner chip thickness (h) becomes (for a 45° KAPR, it is approx. 75% that of a 0° KAPR). This can be seen in below. Therefore as the KAPR increases, the cutting resistance decreases resulting in longer tool life. Note however, if the chip thickness is too large then the cutting resistance can increase leading to vibrations and shortened tool life.

Lead Angle and Chip Thickness

Corner Angle and Crater Wear

Below shows wear patterns for different lead angles. When comparing crater wear for 90° and 45° lead angles, it can be clearly seen that the crater wear for 90° lead angle is larger. This is because if the chip thickness is relatively large, the cutting resistance increases and so promotes crater wear. As the crater wear develops then cutting edge strength will reduce and lead to fracturing.

Corner Angle and Crater Wear