How to choose the material for the aluminum alloy die-casting mold?
The working conditions of aluminum alloy die-casting molds are different from other molds, generally working at about 500 °C. In addition to being subjected to high pressure, it is also subjected to the influence of high temperature. Therefore, for the die steel of aluminum alloy die-casting mold, the selection of aluminum alloy die-casting factory still needs to have certain requirements.
1. Excellent machining performance
In addition to CNC machining, most aluminum dies casting molds to require some cutting and fitter repairs. Plastic molds must be made of steel with appropriate hardness so that the service life of the tool can be extended, the cutting performance can be enhanced, and the surface roughness can be reduced to avoid excessive consumption of tools in the aluminum alloy die-casting plant.
2. Good thermal stability
Aluminum alloy die-casting mold parts often have complex shapes, so parts with good thermal stability should be selected as much as possible because, after quenching, the processing difficulty will be greatly increased. The coefficient of linear expansion of the aluminum alloy die-casting mold after heat treatment will be smaller, and the heat treatment will also have smaller deformation, the dimensional change rate caused by temperature difference will also be smaller, and the metallographic structure and mold size are stable, which can be reduced or not. Reprocessing can ensure mold dimensional accuracy and surface roughness requirements.
3. Good polishing performance
High-quality aluminum alloy die castings require small surface roughness of the cavity. Therefore, the cavity must be polished in the aluminum alloy die casting plant, so that the surface roughness can be reduced. For this reason, it is required that the selected steel has fewer impurities, a uniform microstructure, no fiber orientation, and there should be no pitting or orange peel defects during polishing.
4. Sufficient surface hardness and wear resistance
The heat-treated mold should have sufficient surface hardness to ensure sufficient rigidity of the mold. During the working process of the mold, since the filling and flow of the aluminum alloy liquid have to bear a lot of pressure and friction, the mold is required to keep the shape accuracy and dimensional accuracy stable, so as to ensure that the mold has a sufficient service life. The wear resistance of the mold depends on the chemical composition of the steel and the heat treatment hardness. Therefore, increasing the hardness of the mold is beneficial to improve its wear resistance.
In addition, when selecting materials, it is necessary to consider protection against wear and gluing. If there is relative motion between the two surfaces, try to avoid selecting materials with the same tissue structure. In special cases, one surface can be electroplated or nitrided, giving the two surfaces different surface structures.