Cause analysis:

 1. The cutting parameters are unreasonable and the workpiece surface is rough.

 2. The knife edge is not sharp.

 3. The tool clamping is too long and the blade avoidance is too long.

 4. Chip removal, air blowing and oil flushing are not good.

 5. Programming tool feeding mode (forward milling can be considered as far as possible).

 6. The workpiece has burrs.

Improvement methods:

 1. The cutting parameters, tolerance, allowance and feed speed should be set reasonably.

 2. The tool requires the operator to check and replace irregularly.

 3. When clamping the tool, the operator is required to clamp it as short as possible and the blade should not be too long.

 4. For the undercutting of flat knife, R knife and round nose knife, the speed feed setting should be reasonable.

 5. Workpiece has burr: it is directly related to our machine tool, cutting tool and cutting way. Therefore, we should understand the performance of the machine tool and repair the burr edge.