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, oil stone strips, wool wheels, sandpaper, etc. are used, and manual operation is the main method. Special parts such as the surface of a rotating body can use auxiliary tools such as a turntable. For high surface quality requirements, ultra-fine grinding and polishing can be used. Ultra-fine grinding and polishing use a special grinding tool, which is pressed tightly on the surface of the workpiece in a grinding and polishing liquid containing abrasives and rotates at high speed. This technology can achieve a surface roughness of Ra0.008μm. This method is often used in optical lens molds.

2. Chemical polishing
Chemical polishing is to make the microscopic convex parts of the material surface in the chemical medium dissolve preferentially compared to the concave parts, thereby obtaining 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 is highly efficient. The core issue of chemical polishing is the preparation of the polishing liquid. The surface roughness obtained by chemical polishing is generally several 10μm.

3. Electrolytic polishing
The basic principle of electrolytic polishing is the same as that of chemical polishing, that is, it selectively dissolves the tiny protrusions on the surface of the material to make the surface smooth. Compared with chemical polishing, it can eliminate the influence of the cathode reaction and has a better effect. The electrochemical polishing process is divided into two steps: (1) Macro leveling: The dissolved product diffuses into the electrolyte, and the geometric roughness of the material surface decreases, Ra>1μm. (2) Micro-brightness leveling: Anode polarization, surface brightness increases, Ra<1μm.

4. Ultrasonic polishing
Put the workpiece into the abrasive suspension and place it in the ultrasonic field together. Relying on the oscillation of the ultrasonic wave, the abrasive is ground and polished on the workpiece surface. Ultrasonic processing has a small macroscopic force and will not cause deformation of the workpiece, but the tooling is difficult to make and install. Ultrasonic processing can be combined with chemical or electrochemical methods. Based on solution corrosion and electrolysis, ultrasonic vibration is applied to stir the solution to separate the dissolved products on the workpiece surface and make the corrosion or electrolyte near the surface uniform; the cavitation effect of ultrasonic waves in the liquid can also prevent the corrosion process and facilitate surface brightening.

5. Fluid polishing
Fluid polishing relies on high-speed flowing liquid and the abrasive particles it carries to flush the surface of the workpiece to achieve the purpose of polishing. Common methods include abrasive jet processing, liquid jet processing, fluid dynamic grinding, etc. Fluid dynamic grinding is driven by hydraulic pressure so that the liquid medium carrying abrasive particles flows 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 low pressure and mixed with abrasives. The abrasive can be made of silicon carbide powder.

6. Magnetic grinding and polishing
Magnetic grinding and polishing uses magnetic abrasives to form abrasive brushes under the action of a magnetic field to grind the workpiece. This method has high processing efficiency, good quality, easy-to-control processing conditions, and good working conditions. With suitable abrasives, the surface roughness can reach Ra0.1μm.

7. Chemical mechanical polishing
Chemical mechanical grinding technology combines the advantages of chemical grinding and mechanical grinding. It is a commonly used polishing method. Even mobile phone cases, card removal pins, buttons, etc. are polished with surface grinders. While ensuring the material removal efficiency, a more perfect surface can be obtained. The flatness obtained is 1-2 orders of magnitude higher than that of the two types of grinding alone, and the surface roughness from the nanometer level to the atomic level can be achieved. Moreover, the mirror effect of polishing is very bright, without faults, and has good flatness. 

1. Mechanical Polishing
When polishing the inner wall of the steel pipe, you need to put the grinding wheel into the steel pipe and polish the inside of the steel pipe through high-speed rotation. If you feel that the stainless steel pipe is not bright enough, you can also add polishing paste during the polishing process, which can improve the brightness of the steel pipe.
Mechanical polishing can remove a thin layer of metal on the surface of the stainless steel pipe. If there are very deep scratches on the surface of the steel pipe, it is difficult to remove the scratches of the steel pipe only by mechanical polishing. When polishing, it is also necessary to add concentrated polishing liquid and apply appropriate pressure. These operations will increase the polishing time.

2. Electrolytic Polishing
To polish using this method, you need to put the steel pipe in an electrolytic cell first, where the anode is a stainless steel pipe and the cathode is an insoluble metal. After the electrolytic cell is passed through direct current, the tiny bumps on the surface of the stainless steel pipe can be dissolved, making the surface smoother.

3. Chemical Polishing
Put the stainless steel pipe in the polishing liquid to dissolve the raised or sunken parts on the surface of the steel pipe, making the surface of the steel pipe smoother. This polishing method does not require complex mechanical equipment. You only need to configure the polishing liquid to polish multiple stainless steel pipes at the same time, which is more efficient.

4. Ultrasonic Polishing
Soak the stainless steel pipe in the grinding suspension in advance, and then put it into the ultrasonic field together. The stainless steel surface is polished by the back-and-forth oscillation of the ultrasonic wave. Polishing with this method will not cause the stainless steel pipe to deform, but it is very difficult to install. Now combine the ultrasonic and electrochemical methods, put the stainless steel pipe in the chemical solution, and add ultrasonic back-and-forth oscillation while electrolyzing to accelerate the separation of the surface material of the stainless steel pipe.

5. Fluid Polishing
This method mainly uses fast-flowing liquid and abrasive particles to flow rapidly on the surface of the stainless steel pipe to achieve the effect of polishing. The flowing liquid used is a special substance with good fluidity, and the abrasive is the silicon carbide powder that is more common in processing.

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