Points for Attention in Heating Process of Plastic Injection Mold
1. Forging process. This is an important link in the manufacturing process of injection mold working parts. For the injection mold of high alloy tool steel, technical requirements are usually put forward for the metallographic structure such as carbide distribution of the material. In addition, the forging temperature range should be strictly controlled, the correct heating specification should be formulated, the correct forging force method should be adopted, and the slow cooling or timely annealing after forging should be adopted.
2. Preparatory heat treatment. Preparatory heat treatment processes such as annealing, normalizing or quenching and tempering should be adopted according to the different materials and requirements of the working parts of the injection mold to improve the microstructure, eliminate the microstructure defects of the forging blank and improve the processing technology. High carbon alloy die steel after proper preparation heat treatment can eliminate the network secondary carburized body or chain carbide, make carbide spheroidization, refinement, and promote the uniformity of carbide distribution. This is conducive to ensuring the quality of quenching and tempering and improving the life of the die.
3. Quenching and tempering. This is the key link in mold heat treatment. If overheating occurs during quenching and heating, it will not only cause greater brittleness of the workpiece, but also cause deformation and cracking during cooling, which seriously affects the life of the die. Special attention should be paid to preventing oxidation and decarburization during quenching and heating of punch. The heat treatment process specification should be strictly controlled, and vacuum heat treatment can be used when conditions permit. Tempering should be timely after quenching and different tempering processes should be adopted according to technical requirements.
4. Stress relief annealing. After processing parts of injection mould, stress relief annealing treatment should be carried out to eliminate internal stress caused by rough machining so as to avoid excessive deformation caused by quenching.
