Over-polishing The problem of prohibited words 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 phenomena of over-polishing: "orange peel" and "pitting". Excessive polishing occurs mostly in mechanical polishing.
The reason for the "orange peel" of the workpiece. The irregular and rough surface is called "orange peel". There are many reasons for the "orange peel". The most common reason is that the mold surface is overheated or carburized, and the polishing pressure is too high. Too much polishing time is the main reason for "orange peel". For example: polishing wheel polishing, the heat generated by the polishing wheel will easily cause "orange peel". Harder steels can withstand greater polishing pressure, and relatively softer steels are prone to over-polishing. Studies have shown that the time for over-polishing will vary depending on the hardness of the steel.
Measures to eliminate the "orange peel" of the workpiece When the surface quality is found to be poorly polished, many people will increase the polishing pressure and prolong the polishing time. This practice often makes the surface quality worse. The following methods can be used to remedy:
(1) Remove the defective surface, the grinded grain size is one level coarser than the previous sand number, and then grind, the polishing force is lower than the previous one.
(2) Perform stress relief at a temperature of 25 ℃ lower than the tempering temperature, use the finest sand number to grind before polishing until a satisfactory result is achieved, and finally polish with a lighter force.