Watch parts use medium frequency induction heating power for heat treatment. What brittle fracture defects can be easily caused if improper operation is performed?

Watch parts have many requirements on the accuracy and surface quality of the parts. After parts are heat treated by medium frequency induction heating power supply, various defects will occur due to various reasons. After a defect occurs in a part, the cause of the defect must be correctly analyzed and preventive measures and solutions must be proposed.

Watch parts use medium frequency induction heating power for heat treatment. If not operated properly, the following brittle fracture defects may easily occur:

1. Balance shaft Common brittle fractures of the balance shaft include cracking of the grinding journal, fracture of the riveted seat, twisting of the grinding journal, etc. The causes and solutions of the brittle fracture are as follows:

1) If the quenching temperature is high, the martensite structure will coarsen and the brittleness will increase. Therefore, when performing specific heat treatment processes, we must strictly control the quenching temperature.

2) The automatic feeding mechanism of the grinder is worn and broken during the feeding operation. For this reason, we should repair the grinding wheel in time, and the diamond grinding wheel particle size should be selected reasonably.

3) The riveting machine is not precise enough, causing the seat to break. In view of this, the accuracy of the riveting machine must ensure the process requirements.

2. Escape wheel. The brittle fracture of the escape wheel includes broken teeth caused by rolling and throwing the locking surface or grinding the teeth, and cracking of the wheel spokes during electroplating after assembly and riveting. The causes and solutions are as follows:

1) The quenching temperature is relatively high, therefore, we should strictly process the heat treatment.

2) Electroplating is hydrogen embrittled. Therefore, a stress relief treatment is required before electroplating.

3. The common brittle fracture of the stem is breakage. The causes and solutions are as follows:

1) The quenching temperature is too high, we should strictly follow the process quenching operation.

2) Stress concentration at the change of cross-section. The solution is to use arc transitions as much as possible at cross-section changes, and no sharp angles are allowed to reduce stress concentration.