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There are many methods for polishing stainless steel, including mechanical polishing, chemical polishing, electrolytic polishing, magnetic polishing, etc.
1. Mechanical polishing
Mechanical polishing is a polishing method that obtains a smooth surface by cutting and plastic deformation of the material surface to remove the convex parts after polishing. Generally, oilstone strips, wool wheels, sandpaper, etc. are used. For special parts such as the rotating surface, auxiliary tools such as turntables can be used. For those with high surface quality requirements, ultra precision grinding and polishing methods can be used. Ultra precision polishing is the use of specially designed grinding tools, which are pressed tightly onto the surface of the workpiece being processed in a polishing solution containing abrasives, and undergo high-speed rotational motion. This process can achieve a surface roughness of Ra0.008 um, which is commonly used in optical lens molds.
2. Chemical polishing
Chemical polishing is the process of allowing the micro protruding and concave parts of a material to dissolve preferentially in a chemical medium, resulting in a smooth surface. The main advantage of this method is that it does not require complex equipment, can polish workpieces with complex shapes, can polish many workpieces at the same time, and has high efficiency. The core issue of chemical polishing is the preparation of polishing solution. The surface roughness obtained by chemical polishing is generally around 10um.
3. Electrolytic polishing
The basic principle of electrolytic polishing is the same as chemical polishing, which relies on selective dissolution of small protrusions on the surface of the material to make the surface smooth. Compared with chemical polishing, it can eliminate the influence of cathodic reactions and achieve better results. The electrochemical polishing process is divided into two steps:
(1) Macroscopic leveling, diffusion of dissolved products into the electrolyte, and reduction of geometric roughness on the material surface, Ra＞1um 。
(2) Micro light leveling, anodic polarization, and increased surface brightness, Ra＜1um。
4. Ultrasonic polishing
Place the workpiece in an abrasive suspension and place it together in an ultrasonic field, relying on the oscillation of ultrasonic waves to grind and polish the abrasive on the surface of the workpiece. Ultrasonic machining has low macroscopic force and will not cause deformation of the workpiece, but it is difficult to manufacture and install the fixture. 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, causing the dissolved products on the surface of the workpiece to detach and the corrosion or electrolyte near the surface to be uniform; The cavitation effect of ultrasound in liquid can also suppress the corrosion process and promote surface brightening.
5. Fluid polishing
Fluid polishing relies on the high-speed flow of liquid and the abrasive particles carried by it to wash the surface of the workpiece to achieve the purpose of polishing. Common methods include abrasive jet machining, liquid jet machining, fluid dynamic grinding, etc. Fluid dynamic grinding is driven by hydraulic pressure, which causes the liquid medium carrying abrasive particles to flow back and forth at high speed over the surface of the workpiece. The medium is mainly made of special compounds (polymer like substances) with good flowability at lower pressures and mixed with abrasives, which can be made of silicon carbide powder.
6. Magnetic grinding and polishing
Magnetic grinding and polishing is the process of using magnetic abrasives to form abrasive brushes under the action of a magnetic field for grinding and processing workpieces. This method has high processing efficiency, good quality, easy control of processing conditions, and good working conditions. By using appropriate abrasives, the surface roughness can reach Ra0.1 um.
