Holes are caused by the vibration of the drill bit during the machining process. The vibration of the collet can greatly harm the precision of diameter and hole positioning, so it is necessary to replace the collet immediately when it is severely damaged. When machining small round holes on the deep holes of the heat exchanger tube plate, the measurement and adjustment of the vibration are quite difficult, so it is advisable to use a coarse shank small diameter drill bit with good parallelism between the blade and the shank. When using re-grind drill bits for machining, the reasons for the reduction in hole precision are often due to the uneven shape. Controlling the blade slope can control the cutting and expansion of the hole.

Drilling on Inclines and on Surfaces with Slopes

When the cutting edge or the penetration surface of a drill bit is oblique, diagonal, or stepped, the positioning accuracy is weaker, as the drill bit then undergoes axial single-layer cutting, reducing the lifespan of the milling tool.

To enhance the positioning accuracy of deep-hole machining on heat exchanger tube plates, the following strategies can be adopted:

First, bore the center hole of the management center.

2. Machining hole seats with alloy milling cutters.

3. Utilizing drill bits with excellent entry and rigidity.

4. Decrease cutting speed.