FUNCTION OF TOOL FEATURES FOR TURNING

The side cutting edge angle reduces impact load and effects the amount of feed force, back force and chip thickness.

SIDE CUTTING EDGE ANGLE (LEAD ANGLE)

SIDE CUTTING EDGE ANGLE (LEAD ANGLE)

Effects of Side Cutting Edge Angle (Lead Angle)

  1. At the same feed rate, increasing the side cutting edge angle increases the chip contact length and decreases chip thickness. As a result, the cutting force is dispersed on a longer cutting edge and tool life is prolonged. (Refer to the chart.)
  2. Increasing the side cutting edge angle increases force a'. Thus, thin, long workpieces suffer from bending in some cases.
  3. Increasing the side cutting edge angle decreases chip control.
  4. Increasing the side cutting edge angle decreases the chip thickness and increases chip width. Thus, breaking chips is difficult.

END CUTTING EDGE ANGLE

The end cutting edge angle avoids interference between the machined surface and the tool (end cutting edge). Usually 5°–15°.

Effects of End Cutting Edge Angle

1. Decreasing the end cutting edge angle increases cutting edge strength, but it also increases cutting edge temperature.

2. Decreasing the end cutting edge angle increases the back force and can result in chattering and vibration while machining.

3. Small end cutting edge angle for roughing and large angle for finishing are recommended.

Effects of End Cutting Edge Angle

CUTTING EDGE INCLINATION

Cutting edge inclination indicates inclination of the rake face. During heavy cutting, the cutting edge receives an extremely large shock at the beginning of each cut. Cutting edge inclination keeps the cutting edge from receiving this shock and prevents fracturing. 3°–5° in turning and 10°–15° in milling are recommended.

Effects of Cutting Edge Inclination

  1. Negative (-) cutting edge inclination disposes chips in the workpiece direction, and positive (+) disposes chips in the opposite direction.

  2. Negative (-) cutting edge inclination increases cutting edge strength, but it also increases the back force of cutting resistance. Thus, chattering can easily occur.