The Air Cooler Mould usually needs to work in a high-temperature environment of 150 to 200 degrees Celsius when producing plastic products in an injection moulding machine. Therefore, great attention should be paid to the selection of raw materials in the process of manufacturing the mould. This will play a crucial role in determining the overall service life of the mould and the quality of the plastic products produced in the later period. What performance requirements should be met when selecting the steel materials for the air cooler mould?
1. Sufficient surface hardness and wear resistance.
The hardness of the injection mould is usually below 50-60HRC. The heat-treated mould should have sufficient surface hardness to ensure the mould has sufficient rigidity. During the operation of the mould, due to the filling and flowing of the injection mould, the mould must bear relatively large compressive stress and friction force, which requires the mould to maintain the stability of shape accuracy and dimensional accuracy to ensure the mould has sufficient service life. The wear resistance of the mould depends on the chemical composition of steel and the heat-treated hardness. Therefore, enhancing the hardness of the mould is conducive to enhancing its wear resistance.
2. Excellent machinability.
In addition to EMD processing, most injection moulding dies need certain cutting processing and fitter repair. In order to prolong the service life of cutting tools and enhance cutting performance, injection moulding dies reduce surface roughness, and the hardness of steel used in injection moulding dies must be appropriate.
3. Carbon steel has certain strength and wear resistance. After quenching and tempering, it is mostly used for mould frame materials, high carbon tool steel and low alloy tool steel. After heat treatment, it has higher strength and wear resistance and is mostly used for forming parts. However, high carbon tool steel is only suitable for forming parts with small size and simple shape due to its large heat treatment deformation.
4. Good thermal stability.
Parts of injection mould are often complicated in shape and difficult to process after quenching. Therefore, it is necessary to try to choose the one with good thermal stability. When the two-color mould is processed after heat treatment, the linear expansion coefficient is small, the heat treatment deformation is small, the dimensional change rate caused by temperature difference is small, the metallographic structure and the mould size are stable, and the processing can be reduced or stopped, thus ensuring the mould size accuracy and surface roughness requirements.
5. Good polishing performance.
For high-quality two-color injection moulded products, the roughness value of the cavity surface is required to be small. For example, the roughness value of the cavity surface of the injection mould is required to be less than Ra 0.1 ~ 0.25, and the optical surface is required to be Ra<0.01nm. The cavity must be polished to reduce the surface roughness value. For this reason, the selected steel requires less miscellaneous injection processing quality, fine and uniform structure, no fiber directionality, and no pitting or orange peel defects during polishing.
There are many ways to operate the heat treatment process, including blocking holes, binding holes, mechanical fixing, suitable heating methods, accurate selection of the cooling direction of the mould and the movement direction in the cooling medium, etc. A reasonable tempering heat treatment process is also an effective measure to reduce the deformation of the mould for household products.
