Since mechanical polishing is mainly done manually, polishing technology is still the main reason affecting polishing quality. In addition, it is also related to the mold material, the surface condition before polishing, and the heat treatment process. High-quality steel is a prerequisite for obtaining good polishing quality. If the surface hardness of the steel is uneven or there are differences in characteristics, polishing difficulties will often occur. The types of debris and pores in the steel are not conducive to polishing.
1. The influence of different hardness on the polishing process
2. The increase in hardness increases the difficulty of grinding, but the roughness after polishing decreases. As the hardness increases, the polishing time required to achieve a lower roughness increases accordingly. At the same time, the hardness increases and the possibility of over-polishing decreases.
3. The influence of the surface condition of the workpiece on the polishing process
During the crushing process of cutting machining, the surface of steel will be damaged due to heat, internal stress or other factors. Improper cutting parameters will affect the polishing effect. Therefore, high-speed CNC finishing is required, and the cutting amount is controlled within 0.05-0.07mm.JN The surface after EDM is more difficult to grind than the surface after ordinary machining or heat treatment. Therefore, before the end of EDM, it should be trimmed with precision EDM, otherwise the surface will form a hardened Pu layer. If the electric spark trimming rules are not selected properly, the depth of the heat-affected layer can reach 0.4mm. The hardness of the hardened layer is higher than the basic hardness and must be removed. Therefore, a rough grinding process is added to completely remove the damaged surface layer and form an evenly rough metal surface, which provides a good foundation for polishing process.