4. Reasons for the formation of "pitting" on the surface of the workpiece
Due to some non-metallic impurities in the steel, usually hard and brittle oxides, which are pulled out from the surface of the steel during the polishing process to form micro-pits or pitting, the main factors causing "pitting" are as follows:
(1) The polishing pressure is too large and the polishing time is too long.
(2) The purity of the steel is insufficient and the content of hard impurities is high.
(3) The surface of the mold is rusted.
(4) Black leather material is not removed.
5. Measures to eliminate pitting corrosion of the workpiece
(1) Carefully re-grind the surface, the grit size is slightly thicker than the previously used particle size, and the final step of grinding is performed with soft and sharp oil stone before the polishing process.
(2) When the sand size is less than 1mm, the softest polishing tool should be avoided.
(3) Use the shortest polishing time and the minimum polishing force as much as possible.