Mechanical polishing, electrolytic polishing, chemical polishing - Introduction to several classifications of polishing

 Feature Articles     |      2018-08-27 21:26

1. Mechanical polishing is a polishing method that removes the polished convex portion by plastic deformation on the surface of the material to obtain a smooth surface. Generally, oil stone strips, wool wheels, sandpaper, etc. are used, and manual operations are mainly used, and special parts such as the surface of the rotating body are used. Auxiliary tools such as turntables can be used, and the method of superfine polishing can be used with high surface quality requirements. Ultra-fine grinding and polishing is a special-purpose grinding tool. In the polishing liquid containing abrasive, it is pressed against the machined surface to perform high-speed rotary motion. With this technology, the surface roughness of Ra0.008 can be achieved, which is the highest among various polishing methods. This method is often used in optical lens molds.

2. Chemical polishing is to make the material slightly swelled in the chemical medium, and the concave portion is preferentially dissolved, thereby obtaining a smooth surface. The main advantage of this method is that it can polish a workpiece with complex shapes without complicated equipment, and can polish many workpieces at the same time with high efficiency. The core issue of chemical polishing is the formulation of the polishing fluid. The surface roughness obtained by chemical polishing is generally several tens of micrometers.

3. The basic principle of electropolishing is the same as chemical polishing, that is, by selectively dissolving tiny protruding portions on the surface of the material to make the surface smooth. Compared with chemical polishing, the effect of the cathode reaction can be eliminated, and the effect is better.

4. Ultrasonic polishing The workpiece is placed in the abrasive suspension and placed together in the ultrasonic field. The ultrasonic vibration is applied to the abrasive surface of the workpiece. Ultrasonic machining has a small macroscopic force and does not cause deformation of the workpiece, but it is difficult to manufacture and install the tooling. Ultrasonic processing can be combined with chemical or electrochemical methods. On the basis of solution corrosion and electrolysis, ultrasonic vibration is applied to stir the solution to dissociate the dissolved products on the surface of the workpiece, and the corrosion or electrolyte near the surface is uniform. The cavitation of the ultrasonic wave in the liquid can also inhibit the corrosion process, which is beneficial to surface illuminating.

5. Fluid polishing relies on high-speed flowing liquid and abrasive particles carried by it to wash the surface of the workpiece for polishing. Common methods include abrasive jet processing, liquid jet processing, and hydrodynamic grinding. Hydrodynamic grinding is driven hydraulically to allow the liquid medium carrying the abrasive particles to flow back and forth across the surface of the workpiece at high speed. The medium is mainly made of a special compound (polymeric substance) having a good fluidity at a relatively low pressure and is doped with an abrasive, and the abrasive may be a silicon carbide powder.