For mechanical parts, many require precision, but for a number of reasons, the surface roughness of the helical rack is different:
 

1. The precision of the machine tool transmission chain is not high. During operation, vibration or impact occurs, which affects the instability of the machine tool transmission.

2. The contact between the spindle of the table and the conical guide surface of the table is not satisfactory. The contact of the tapered guide surface is too hard, the table rotates heavily, and vibration occurs during operation, which causes errors in processing.

3. The knife mechanism is not working properly, and the knife is scraped onto the surface of the workpiece.

4. The quality of the toothed cutter is poor.

5. The feed rate is too large, causing the cutting of the rack to be not timely, which results in rough surface of the rack.

6. The rack blank is not installed properly, and vibration occurs during cutting.

7. The cutting fluid is dirty or rushed into the cutting groove, causing the surface quality of the rack to be unqualified.