In order to improve the use performance of the mold, many manufacturers will process the mold properly. Mold processing refers to the processing of the forming and blank making tools, in addition to the cutting mold and die-cutting mold. But in many cases, the processing defects will also be reflected after the mold processing, resulting in the decline of the mold performance. How to prevent the quenching crack in the mold processing?
1. The shape effect is mainly caused by design factors, such as too small fillet R, improper hole location and bad section transition.
2. Overheating (overburning) is mainly caused by improper temperature control or temperature running, nonstandard and unreasonable vacuum heat treatment process, especially inadequate tempering. The preventive measures include maintenance, calibration of temperature control system, correction of process temperature, adding sizing block between workpiece and furnace bottom plate, etc.
3. Decarburization is mainly caused by overheating (or overburning), unprotected heating of air furnace, small machining allowance, residual decarburization layer in forging or preparation heat treatment, etc. the preventive measures are controlled atmosphere heating, salt bath heating, vacuum furnace and box furnace adopting case protection or using anti-oxidation coating material; machining allowance is increased by 2-3mm.
4. Improper cooling is mainly caused by improper selection of coolant or supercooling. It is necessary to master the cooling characteristics of quenching medium or tempering treatment.
5. The structure of raw materials is poor, such as serious carbide segregation, poor forging quality, improper preparation heat treatment method, etc. the preventive measures are to adopt correct forging process and reasonable preparation heat treatment system.