Stresses include thermal stresses and mechanical stresses, mainly due to mechanical, chemical, and operational shocks. Heat is specifically produced in the following ways.
1. In the process of die casting production
(1) The cooling temperature control system should be set to keep the working temperature of the mold within a certain range.
(2) During the production process, the mold temperature is continuously increased. When the mold temperature is overheated, the mold is easily generated, and the moving parts are broken, resulting in damage to the mold surface.
(3) The mold should be preheated to a certain temperature before production. Otherwise, when the high temperature molten metal is filled, chilling occurs, which causes the temperature gradient of the inner and outer layers of the mold to increase, forming thermal stress, causing the surface of the mold to crack or even crack.
2. During the mold processing
(1) The stress generated during quenching of steel is the result of the superposition of thermal stress during cooling and the structural stress during phase change. Quenching stress is the cause of deformation and cracking. Solid must be tempered to eliminate stress.
(2) Improper heat treatment will cause the mold to crack and prematurely scrap, especially the quenching and tempering, no quenching, and then the surface nitriding process, surface cracking and cracking will occur after several thousand die casting.