5. Mechanical cracks. Mechanical cracks due to mechanical stress cause the cutting edge to break.

Reason: The cutting force is constantly changing and is affected by mechanical stress, causing cracks parallel to the cutting edge.

Solution: 1. Choose a grade with good toughness. 2. Reduce the feed per tooth. 3. Change the offset position of the tool to the workpiece. 4. Try to use down milling.

6. Plastic deformation. The cutting edge is subjected to high temperature and high pressure, causing plastic deformation.

Reason 1. Cutting speed is too fast. Solution: Reduce cutting speed.

Reason 2. The feed volume is large. Solution: Reduce feed per tooth.

Reason 3. The blade material is soft. Solution: Choose a wear-resistant blade grade.

7. Gap. The cutting edge is damaged by chip impact, resulting in poor finish.

Reason 1. The blade has poor wear resistance. Solution: Choose wear-resistant grades.

2. The surface of the workpiece is hard and contains inclusions. Solution: Blunt the edge of the blade and grind a negative chamfer. Or reduce the main deflection angle.

8. Built-up edge. When milling sticky materials, chipping occurs due to sticking to the tool, resulting in poor surface finish.

Reason 1. Cutting speed is too low. Solution: Increase cutting speed.

Reason 2. Negative rake angle is adopted. Solution: Use a positive rake angle.

Reason 3. The workpiece material is welded to the cutting edge. Solution: Use coated blades or polish the blade surface; no coolant is required.