There are usually two reasons for the steel grain phenomenon in the mold: one is the problem of the mold steel itself, many mold makers choose poor quality (cheap) steel to make the mold in order to save cost, resulting in the surface of the mold after the mold polishing to appear grain, and some fine lines. At the same time, under the light will lead to distortion of the light, mold polishing can only reduce the phenomenon of mold steel grain. Secondly, the skill of the mold polisher is not good. If you choose Fushun Special Steel, the quality can be guaranteed, and the phenomenon of steel grain on the surface of the mold can be avoided due to the lack of skill of the mold polishing technician.
Mould surface polishing is not only affected by polishing equipment and technology, but also affected by the mirror of the mold material. Mirror mold material is not only the chemical composition of the problem, more importantly, the smelting requirements of vacuum degassing, argon protection casting ingot, vertical casting and rolling, soft forging and a series of advanced technology. Mirror mold steel internal defects, impurities, fine particle size, high degree of dispersion, fine metal grain size, good uniformity and a series of advantages to meet the polishing to mirror.
The effect of mold steel smelting on mirror polishing process
Non-metallic inclusions in steel, bubbles, oxides, sulfides, etc. is the main reason for the formation of pinholes and holes in the mold steel mirror polishing and grinding. Therefore, where the surface roughness requirements of high plastic mold, generally shall not be used to add sulfur free cutting steel; even if it is not a free cutting steel, if the steel in the oxides, sulfide inclusions content is higher, in the grinding process is also easy to fall off the formation of pinholes. Therefore, the use of vacuum smelting or electroslag remelting process, will effectively improve the purity of the steel, thereby improving the polishing performance of the steel. Die steel in the organization of unevenness is also another reason to affect the polishing performance. Uneven organization of the micro-area, plus banded segregation, etc. may make the steel in the mirror processing of very fine hairline and grinding spots, pits and other defects, in order to prevent segregation, we must master the steel after the pouring technology and the crystallization of the quality of the ingot, in addition to full forging to ensure that the steel’s densification, if you can be carried out to homogenize the heat treatment or electroslag remelt smelting, but also effective in reducing the segregation, thus Improve the polishing performance of the steel.
Impact of Polishing Technology on Mirror Polishing Processing
Polishing technology also plays a major role in order to obtain a demanding mirror polish finish. During pre-grinding the surface should be protected from temperatures that may cause changes in the organization. Therefore, in addition to sufficient cooling, the selection of the correct oil stone is very important. Grinding pressure plays a large role here and can be increased unexpectedly when the stone is coated, which can cause an increase in temperature. A better solution is to always change the direction of grinding when polishing a surface. Avoid excessive pressure on the surface joints when polishing, otherwise the softer substrate will be eroded, with the result that the carbides will break away, subsequently cracking and leaving defects.
