1. Mechanical polishing
Mechanical polishing is a polishing method that removes the polished convex part by cutting and plastic deformation of the material surface to obtain a smooth surface. Generally, oil stone strips, wool wheels, sandpaper, etc. are used, and manual operations are mainly used. Special parts such as the surface of a rotating body can be polished. Using auxiliary tools such as turntables, ultra-fine grinding and polishing methods can be used for high surface quality requirements. Ultra-fine polishing is to use a special abrasive tool, which is pressed tightly on the surface of the workpiece to be processed in the polishing liquid containing abrasives for high-speed rotation. Using this technology can achieve a surface roughness of Ra0.008, which is the highest among various polishing methods. Optical lens molds often use this method.
2, chemical polishing
Chemical polishing is to make the microscopic convex part of the surface of the material dissolve preferentially compared with the concave part in the chemical medium, so as to obtain a smooth surface. The main advantage of this method is that it does not require complex equipment, can polish workpieces with complex shapes, and can polish many workpieces at the same time, with high efficiency. The core problem of chemical polishing is the preparation of polishing fluid. The surface roughness obtained by chemical polishing is generally tens of microns.
The basic principle of electrolytic polishing is the same as that of chemical polishing, that is, to make the surface smooth by selectively dissolving the tiny protrusions on the surface of the material. Compared with chemical polishing, it can eliminate the influence of cathode reaction, and the effect is better. The electrochemical polishing process is divided into two steps.
① The macroscopically leveled dissolved product diffuses into the electrolyte, and the surface roughness of the material decreases, Ra>lum.
② Microscopic flat anodic polarization, improved surface roughness, Ra<lum.
4, ultrasonic polishing
The workpiece is put into the abrasive suspension and placed together in the ultrasonic field, and the abrasive is ground and polished on the surface of the workpiece relying on the oscillation of the ultrasonic wave. Ultrasonic machining has a small macroscopic force and will not cause deformation of the workpiece, but it is difficult to manufacture and install tooling. Ultrasonic machining can be combined with chemical or electrochemical methods. On the basis of solution corrosion and electrolysis, ultrasonic vibration is applied to stir the solution, so that the dissolved products on the surface of the workpiece are separated, and the corrosion or electrolyte near the surface is uniform; the cavitation effect of ultrasonic waves in the liquid
It can also inhibit the corrosion process. It is beneficial to surface brightening.
5, fluid polishing
Fluid polishing relies on the high-speed flowing liquid and the abrasive particles carried to scour the surface of the workpiece to achieve the purpose of polishing. Commonly used methods include abrasive jet processing, liquid jet processing, hydrodynamic grinding, etc. Hydrodynamic grinding is driven by hydraulic pressure, so that the liquid medium carrying abrasive particles flows back and forth across the surface of the workpiece at high speed. The medium is mainly made of a special compound (polymer-like substance) with good fluidity under relatively low pressure and mixed with abrasives. The abrasives can be silicon carbide powder.