The working conditions of the Trash Can Mould are diffe […]
The working conditions of the Trash Can Mould are different from those of the cold stamping mould. Generally, the mould must work at 150℃ to 200℃, and besides being subjected to pressure, it must also bear the influence of temperature. According to the different service conditions and processing methods of trash can mould, the basic performance requirements of steel for trash can mould are roughly summarized as follows:
Excellent machinability: Most plastic moulding dies need cutting and fitter repair besides EMD machining. In order to prolong the service life of cutting tools, enhance cutting performance and reduce surface roughness, the hardness of steel for trash can mould must be appropriate.
Good thermal stability: the shape of the parts injected into the trash can mould is often complex and difficult to process after quenching, so it should be selected as far as possible with good thermal stability. When the two-color mould is formed and 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, and the metallographic structure and mould size are stable, which can reduce or stop processing, thus ensuring the dimensional accuracy and surface roughness requirements of the mould.
Good polishing performance: High-quality two-color injection moulded plastic products require small roughness of cavity surface. For example, the surface roughness value of injection mould cavity should be less than Ra 0.1 ~ 0.25, and the optical surface should be Ra<0.01nm. The cavity should be polished to reduce the surface roughness value. For this reason, the steel selected requires less impurities, fine and uniform microstructure, no fiber directionality, and no pitting or orange peel defects during polishing. Adequate surface hardness and wear resistance: the hardness of plastic mould is usually below 50-60HRC, and the heat-treated trash can mould should have sufficient surface hardness to ensure the mould has sufficient rigidity. Because of the filling and flowing of plastic, the mould has to bear great compressive stress and friction force, which requires the mould to keep the stability of shape accuracy and dimensional accuracy, and ensure the mould has enough service life. The wear resistance of mould depends on the chemical composition and heat treatment hardness of steel, so enhancing the hardness of mould is beneficial to enhance its wear resistance.