(1) Over-polishing The biggest problem encountered in the daily polishing process is “over-polishing”, which means that the longer the polishing time, the worse the quality of the mold surface. There are two types of over-polishing: “orange peel” and “pitting.” Excessive polishing often occurs in mechanical polishing.
(2) The reason for the “orange peel” on the workpiece
Irregular and rough surfaces are called “orange peels”. There are many reasons for “orange peeling”. The most common cause is carburization caused by overheating or overheating of the mold surface. Excessive polishing pressure and polishing time are the main causes of “orange peel”.
For example: polishing wheel polishing, the heat generated by the polishing wheel can easily cause “orange peel”.
Harder steels can withstand greater polishing pressures, while relatively softer steels are prone to overpolishing. Studies have shown that the time to overpolish varies depending on the hardness of the steel material.
(3) Measures to eliminate the “orange peel” of the workpiece
When it is found that the surface quality is not well polished, many people will increase the polishing pressure and prolong the polishing time, which often makes the surface quality better. the difference. This can be remedied using:
1. Remove the defective surface, the grinding particle size is slightly coarser than before, use the sand number, and then grind again, the polishing strength is lower than the last time.
2. Stress relief is carried out at a temperature lower than the tempering temperature of 25 ℃. Before polishing, use fine sand to grind until a satisfactory effect is achieved, and finally lightly press and polish.
(4) The reason for the formation of “pitting corrosion” on the surface of the workpiece is that some non-metallic impurities in the steel, usually hard and brittle oxides, are pulled off from the steel surface during the polishing process, forming micro-pits or pitting corrosion.
lead to “
The main factors of “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 not enough, and the content of hard impurities is high.
3) The mold surface is rusted.
4) The black leather is not removed
Post time: Nov-25-2022