Eight points reveal the specific cause of the mold burst(1)

Due to different stamping procedures and different working conditions, the causes of die burst are various. The following is a comprehensive analysis of the causes of die burst in terms of the design, manufacture and use of the die, and find out the corresponding improvement measures.
    1. The mold material is not easy to be broken in subsequent processing
    The mold life of different materials is often different. To this end, two basic requirements are imposed on the material of the working parts of the die:
    ① The use performance of the material should have high hardness (58 ~ 64HRC) and high strength, and have high wear resistance and sufficient toughness, heat treatment deformation is small, and there is a certain degree of heat hardness;
    ② Good process performance. The manufacturing process of punching parts is generally more complicated. Therefore, it must have adaptability to various processing technologies, such as forgeability, machinability, hardenability, hardenability, sensitivity to quench cracking, and grinding processability. Generally, according to the material characteristics, production batches, precision requirements, etc. of the stamping parts, a mold material with excellent performance is selected, while taking into account its processability and economy.
 2.Heat treatment: distortion caused by improper quenching and tempering process
    Practice has proved that the thermal processing quality of the mold has a great impact on the performance and service life of the mold. From the analysis of the reasons for the failure of the mold, it can be known that the 'accident' of mold failure caused by improper heat treatment accounts for more than 40%. The quenching deformation and cracking of the working parts of the mold, and the early fracture in the use process are all related to the hot working process of the mold.
    Forging process: This is an important link in the manufacturing process of mold working parts. For molds of high-alloy tool steels, technical requirements are usually imposed on the metallographic structure such as the carbide distribution of the material. In addition, the forging temperature range should be strictly controlled, the correct heating specifications should be formulated, the correct forging force method should be used, and slow cooling or timely annealing after forging should be used.
Pretreatment heat treatment: Depending on the material and requirements of the working parts of the mold, pretreatment heat treatment processes such as annealing, normalizing or quenching and tempering should be used to improve the structure, eliminate the structural defects of the forging blank, and improve the processability. High-carbon alloy mold steel can eliminate networked secondary cementite or chain carbide through proper preliminary heat treatment, spheroidize and refine carbides, and promote uniformity of carbide distribution. This will help to ensure the quality of quenching and tempering and improve the life of the mold.