In the use of die-casting mold, thermal stress has a great influence on die-casting mold, so what is the specific effect? Let’s take a look at the effect of thermal stress on die-casting molds.
Die-casting molds indicate that thermal stress is the main cause of cracks on the surface of mold forming parts. In the production process of each die-casting part, in addition to the high-speed and high-pressure erosion of the molten metal, the surface of the formed part also absorbs the metal released during the solidification process. Heat produces heat exchange. In addition, due to the thermal conductivity of the mold material, the temperature of the surface layer of the molded part rises sharply, and a large temperature difference is generated with the inside, thereby generating internal stress.
When the molten metal fills the cavity, the surface layer of the cavity first reaches a high temperature and expands, while the mold temperature of the inner layer is lower, and the relative expansion is small, which causes the surface layer to produce compressive stress. After the mold is opened, the surface of the cavity is in contact with air, and is chilled by compressed air and paint to generate tensile stress. This alternating stress increases with the continuation of production. When the fatigue limit of the mold material is exceeded, the mold surface layer will be plastically deformed and cracks will occur.