1. The quality of the tap is not good
Main materials, tool design, heat treatment conditions, machining accuracy, coating quality, etc. For example, the size difference at the transition of the tap section is too large or the transition fillet is not designed to cause stress concentration, and it is easy to break at the stress concentration during use. The cross-section transition at the junction of the shank and the blade is too close to the welding port, resulting in the superposition of complex welding stress and stress concentration at the cross-section transition, resulting in a large stress concentration and causing the tap to break during use.
For example, improper heat treatment process. During the heat treatment of the tap, if there is no preheating before quenching, overheating or overburning of quenching, untimely tempering and premature cleaning, it may cause cracks in the tap.
2. Improper selection of taps
For tapping parts with too much hardness, high-quality taps should be used, such as cobalt-containing high-speed steel taps, carbide taps, coated taps, etc. In addition, different tap designs are used in different workplaces. For example, the number, size, angle, etc. of the flute of the tap have an impact on the chip removal performance.
3. The tap does not match the processed material
This problem has been paid more and more attention in recent years. In the past, domestic manufacturers always thought that imported products were good and expensive products were good, but in fact they were suitable. With the continuous increase of new materials and difficult processing, in order to meet this need, the variety of tool materials is also increasing. This requires selecting the appropriate tap product before tapping.
4. The diameter of the bottom hole is too small
For example, when processing ferrous metal material M5×0.5 thread, the cutting tap should use a drill with a diameter of 4.5mm to make a bottom hole. If a 4.2mm drill is used to make a bottom hole by mistake, the part that the tap needs to cut during tapping will inevitably increase. , and then break the tap. It is recommended to select the correct diameter of the bottom hole according to the type of tap and the material of the tapping part. If there is no fully suitable drill bit, you can choose a larger one.
5. The material problem of tapping parts
The material of the tapping part is impure, and there are local hard points or pores, which cause the tap to lose its balance and break instantly.
6. The machine tool does not meet the precision requirements of the tap
The machine tool and clamping body are also very important, especially for high-quality taps, only a certain precision machine tool and clamping body can exert the performance of the tap. The common thing is that the concentricity is not enough. At the beginning of tapping, the starting position of the tap is incorrect, that is, the axis of the spindle is not concentric with the center line of the bottom hole, and the torque is too large during the tapping process, which is the main reason for the breakage of the tap.
