How to solve common problems in Medical mold polishing?
Date: October 17, 2024
(1) Excessive polishing
The biggest problem encountered in the daily polishing process is “excessive polishing”, which means that the longer the polishing time, the worse the quality of the mold surface. There are two phenomena of excessive polishing: “orange peel” and “pitting”. Excessive polishing often occurs in mechanical polishing.
(2) The reason for the appearance of “orange peel” on the workpiece
Irregular and rough surfaces are called “orange peel”, and there are many reasons for the formation of “orange peel”. The most common reason is due to overheating or excessive carburizing of the mold surface. Excessive polishing pressure and long polishing time are the main reasons for the formation of “orange peel”. For example, when polishing with a polishing wheel, the heat generated by the polishing wheel can easily cause “orange peel”. Hard steel can withstand higher polishing pressure, while relatively soft steel is prone to over polishing. Research has shown that the time for over polishing to occur varies depending on the hardness of the steel.
(3) Measures to eliminate “orange peel” on workpieces
When the surface quality is found to be poor, many people increase the polishing pressure and prolong the polishing time, which often makes the surface quality worse.
The following methods can be used to remedy the situation:
1) Remove the defective surface, grind it to a slightly coarser particle size than the previous sand grade, and then grind it with a lower polishing force than before.
2) Stress relief is carried out at a temperature 25 ℃ lower than the tempering temperature. Before polishing, the finest grit is used for grinding until satisfactory results are achieved. Finally, polishing is carried out with lighter force.
(4) Reasons for the formation of “pitting corrosion” on the surface of workpieces
Due to some non-metallic impurities in steel, usually hard and brittle oxides, they are pulled out from the surface of the steel during polishing, forming micro pits or pitting corrosion. The main factors causing “pitting corrosion” are as follows:
1) The polishing pressure is too high and the polishing time is too long.
2) The purity of steel is insufficient, and the content of hard impurities is high.
3) The surface of the mold is rusted.
4) The black leather material has not been removed.
(5) Measures to eliminate pitting corrosion on workpieces
How to solve common problems in Medical mold polishing?
1) Carefully regrind the surface with slightly coarser sand particles than previously used, using soft and sharp oilstone for the final step of grinding before proceeding with the polishing procedure.
2) When the sand particle size is less than 1 mm, the softest polishing tool should be avoided.
3) Use the shortest possible polishing time and minimum polishing force.
The polishing of the cavity in the mold manufacturing process is a very important process, which is related to the quality and service life of the mold, and also determines the quality of the product. Mastering the working principle and process of polishing, choosing a reasonable polishing method, can improve the quality and lifespan of molds, and thus enhance the quality of products.
