Polishing processing methods can generally be divided into wet research, dry research and semi-dry research 3 categories. ①Wet research: also known as sand polishing, the liquid polishing agent is successively injected or coated in the metal polishing and surface, the abrasive between the workpiece and the grinding tool to continuously improve the sliding and rolling, constituting a cutting speed movement. ② Wet polishing can generally be used for coarse polishing, the particle size of the micronized abrasives used coarse than W7. ③ Dry polishing: also known as embedded sand polishing, the abrasive quality evenly in the pressure embedded in the grinding tool surface layer, polishing only a small amount of stearic acid on the surface of the grinding tool as a mixture of grease and other auxiliary teaching materials. Dry polishing is often used for fine polishing, the particle size of the micronized abrasive used is finer than W7.④ Semi-dry polishing: similar to wet polishing, the polishing agent used is a paste polishing paste. Polishing techniques can be managed by hand or by personnel on a polishing press with magnetic influence. Before polishing the workpiece must first use some other business processing methods to obtain a high degree of precision in pre-processing operations, the polishing time required to leave a margin of 5 – 30 microns in general.
The polishing tool is a tool to polish and shape the workpiece. The hardness of the polishing agent carrier should be lower than the hardness of the workpiece, and has a certain degree of wear resistance. The microstructure of wet grinding tool consists of ferrite magnetic polisher and uniform fine pearlite. Mild steel grinding tools are usually used for polishing threads below m5 and small and fluffy workpieces. When polishing small holes and soft metal materials, brass and copper abrasives are mainly used. The grinding tools should have good rigidity and their working surfaces should have high geometric accuracy. The grinding tools are also cut and worn during the polishing process. Smooth running of the grinding tool can improve the accuracy, so that the workpiece can be machined with higher accuracy than the initial accuracy of the grinding tool.
Correct handling of the trajectory of the magnetic polishing machine is an important condition to improve the quality of polishing. In plane polishing, the general plea: (1) the polishing stroke length of each point on the workpiece should be as close as possible; (2) the trajectory of the workpiece should be uniformly distributed over the entire surface of the abrasive tool to facilitate uniform wear of the abrasive tool; (3) the curvature change of the trajectory should be small to ensure the smooth movement of the workpiece; (4) the trajectory of any point of the workpiece should be avoided as far as possible. Less cutting heat, polishing is generally carried out at low pressure and low speed. Rough grinding pressure is less than 0.3 MPa, fine grinding pressure is generally 0.03-0.05 MPa. rough grinding speed is generally 20-120 m / min, fine grinding speed is generally 10-30 m / min.