How to polish metal to a mirror surface

Polishing metal into a mirror surface has the following four methods:

1, chemical polishing

Chemical polishing and electrochemical polishing process, compared with its biggest advantage is that it does not require DC power supply and special fixtures, can polish the shape of complex parts, high productivity. In terms of functionality, chemical polishing in addition to physical and chemical cleanliness of the surface, but also remove the surface of the mechanical damage layer and stress layer, to get the mechanical cleanliness of the surface, which is conducive to preventing localized corrosion of the parts, improve mechanical strength, extend the service life of parts.

The basic composition of chemical polishing solution includes corrosive agent, oxidizer and water. Corrosive agent is the main ingredient, if dissolved in the solution, polishing can not be carried out. Oxidizers and additives can inhibit the process, so that the reaction in the direction of polishing. Water regulates the concentration of the solution and facilitates the diffusion of reaction products.

2, electrolytic polishing

Electrolytic polishing is a special anodic process, in the entire anodic electrolytic polishing process, the surface at the same time, two contradictory processes, that is, the metal surface oxide film is constantly generated and dissolved.

But the product surface of the raised parts and depression parts of the chemical film into the passive state of the conditions are not the same, and due to anodic dissolution, the anode area of the metal salt concentration continues to increase in the stainless steel products on the surface of the formation of a high-resistivity thick viscous film layer.

The thickness of the thick viscous film on the surface of the product at the micro-convex is not the same, and the anode micro-surface current is unevenly distributed.

Microscopic bumps at the current density is large, dissolve faster, so that the product surface burrs or microscopic bumps preferentially dissolved to achieve the leveling; pits at the current density is small, dissolve also slower. Due to the different distribution of current density, the surface of the product with different rates of film formation and dissolution.

The anode surface at the same time two opposite processes, film formation and dissolution, passivation film generation, dissolution, so that the surface is leveled to achieve a high degree of smoothness and glossy appearance, to meet the purpose of the surface polishing and finishing.

3, fluid polishing?

Fluid polishing is based on the * high-speed flow of liquid and its abrasive particles carried by the workpiece surface to achieve the purpose of polishing. Commonly used methods are: abrasive jet processing, liquid jet processing, fluid power grinding. Fluid power grinding is driven by hydraulic pressure, so that the liquid media carrying abrasive particles of high-speed reciprocating flow over the surface of the workpiece. The media is mainly used in the lower pressure flow through the good special compounds and mixed with abrasives made of abrasive can be used silicon carbide powder.

4, magnetic grinding and polishing

Magnetic grinding and polishing is the use of magnetic abrasives in the magnetic field under the action of the formation of abrasive brushes, the workpiece grinding process. This method of processing efficiency, good quality, easy to control the processing conditions, good working conditions. Using the right abrasive, the surface roughness can reach Ra0.1μm.

Extended information:

Factors affecting the polishing

1 、Gear before shaving Accuracy of the shaving processed after the accuracy of the impact is very large, the general situation before shaving gear accuracy requirements should be lower than after shaving one, and the requirements of the pitch is relatively high, because shaving because the machine tool is not a transmission chain is not a forced transmission, the ability to correct the cumulative error of the pitch is relatively poor, so in general, shaving process as far as possible using hobbing and not using the insertion of gears.

2, stay shaving margin should be appropriate. Stay shaving margin is too small, the accuracy does not meet the requirements, but the margin is too large, but also affects the efficiency of shaving. Some people have done experiments, M4.5 gear, relatively speaking, 0.18mm - 0.22mm is most suitable. In the pre-shaving process accuracy to do a better job in the case can be reduced to stay shaved margin.

3, shaving the cutting amount on the finish also has a great impact. Generally speaking, the reasonable speed is 90-110 m / min, a reasonable knife is 70-120 mm / min, finishing stroke 6-8 times is most appropriate.

4, shaving tooth shape error also affects the finish. After the actual processing experience can be seen, the tool is the correct involute, after shaving the gear is not easy to get the correct involute, there is an error. Relatively speaking with straight razor machining helical gears, the error is smaller than the use of helical razor machining helical gears (to ensure that the angle of intersection of the shaft in the premise of 10-15 degrees). Because it is not yet possible to calculate the size of the shaving error, so the general tooth shape needs to make constant corrections to achieve the correct requirements.

Baidu Encyclopedia - Stainless Steel Polishing