The basic principle of electropolishing is the same as that of chemical polishing, that is, the surface is smooth by selectively dissolving the small protruding part of the material surface. Compared with chemical polishing, the effect of cathode reaction can be eliminated and the effect is better. The electrochemical polishing process is divided into two steps: (1) macro leveling solution diffuses into the electrolyte, and the geometric roughness of the material surface decreases with RA > 1 μ M. (2) The results show that the surface brightness is improved and RA is less than 1 μ M.
1.4 in ultrasonic polishing, the workpiece is put into the abrasive suspension and placed in the ultrasonic field together, and the abrasive is ground and polished on the surface of the workpiece by the oscillating action of the ultrasonic wave. The macro force of ultrasonic machining is small, which will not cause deformation of workpiece, but it is difficult to make 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 to separate the dissolved products on the surface of the workpiece, and the corrosion or electrolyte near the surface is uniform; the cavitation effect of ultrasonic in the liquid can also inhibit the corrosion process and facilitate the surface lighting.
1.5 fluid polishing fluid polishing is to achieve the purpose of polishing by washing the workpiece surface with high-speed flowing liquid and abrasive particles. The common methods are abrasive jet machining, liquid jet machining, hydrodynamic grinding and so on. Hydrodynamic grinding is driven by hydraulic pressure to make the liquid medium carrying abrasive particles flow through the workpiece surface at high speed. The medium is mainly made of special compound (polymer material) with good flowability under low pressure and mixed with abrasive. The abrasive can be silicon carbide powder.
1.6 magnetic abrasive polishing magnetic abrasive polishing is the use of magnetic abrasive under the action of magnetic field to form abrasive brush to grind the workpiece. This method has the advantages of high efficiency, good quality, easy control of processing conditions and good working conditions. The surface roughness can reach ra0.1 μ m with proper abrasive.
The basic method of mechanical polishing in plastic mold processing is different from the surface polishing required in other industries. Strictly speaking, mold polishing should be called mirror processing. It not only has high requirements for polishing itself, but also has high standards for surface flatness, smoothness and geometric accuracy. Surface polishing generally requires only a bright surface. The standard of mirror machining is divided into four levels: Ao = ra0.008 μ m, A1 = ra0.016 μ m, A3 = ra0.032 μ m, A4 = ra0.063 μ M. due to the fact that it is difficult to accurately control the geometric accuracy of parts by electrolytic polishing, fluid polishing and other methods, and the surface quality of chemical polishing, ultrasonic polishing, magnetic abrasive polishing and other methods can not meet the requirements, so the mirror processing of precision mold is mainly mechanical polishing.
About the author