Polishing - what is it? The essence of the process, description, types

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Polishing is a process by which all impurities and irregularities are removed from the surface of the metal and it regains its original luster.

Execution Methods

Currently, there are several types of grinding of metal surfaces:

• The first and most simple and common method is hand polishing. Most often, this method is used when carrying out repair work at the facility.
• The next method is more professional and is called semi-mechanical grinding. This method is carried out using a polishing machine, on which special polishing wheels are put on.
• The third method is machine. It is used in large industrial enterprises. All grinding operations for metal products are carried out by machines in automatic mode.
• The last type is waterjet grinding, carried out on special machines. This method is used only if the volume of metal products that need to be processed is quite large. It should be added that plasma, as well as chemical-mechanical processingcarried out according to the same principle.

Tools and polishing methods

The polishing process is an action that requires certain tools. Moreover, depending on the method of performing this operation, the inventory used also changes. The most commonly used tools are:

• polishing machine;
• grinder;
• electric sharpener;
• drills with latch.

It is worth highlighting the mechanical method of surface treatment, as it has a number of advantages. The first plus worth noting is the ability to control the speed of the machine's circles. This has a positive effect on the entire metal surface treatment process. Polishing is a very delicate process, and therefore, for example, polishing machines can be equipped with a variety of attachments. The material from which these additional elements are made can be wool, leather, fabric.

Special processing method

Surface polishing can be done using combined methods. A combination of several processing methods is most often required when the metal surface is not prepared for work, and is also characterized by the presence of a rough surface. With such shortcomings, most often, before proceeding with the polishing itself, a long-term electrolytic-plasma preparation is carried out. During this step, a large amount of metal is removed.

It is worth noting that this particular method of processing the product is used as a last resort, when it is necessary to restore the luster of the metal coating in a very short time. The disadvantages of this particular processing process include the fact that the energy costs at the initial stage are 100% higher than when processing by other methods. It can be added that polishing occurs in two stages: on the first, the surface is degreased, but on the second, the grinding itself begins.

Hand polished

Today, there are various polishing materials that will help restore the original luster of the metal surface without the use of any special machines. There are three groups of such substances.

The first includes water pastes. Such substances do not contain fats in their composition, but at the same time they are quite capable of cleaning the metal surface from contamination.

The second group is organic substances. The composition of these pastes includes paraffin, as well as several different oils. In addition, such products are further diluted with other types of oils or fatty acids before use.

The third group is diamond pastes, which are considered a revolutionary solution at the present time. Products from this category are able to quickly and effectively clean any metal surface from any contamination.

Polishing with diamond paste

Diamond paste is very good, for example, for polishing cars. Tosuccessfully complete the operation, you must have lappings and several tubes of paste. To start work, it is necessary to apply the paste in an even layer on a rag or any other work surface of the object that will be polished. During practical tests, it was found that in order to achieve greater polishing efficiency with diamond paste, it is worth adding olive or castor oil to it. During the same tests, it was found that the best ratio of paste and oil would be 40 and 60%, respectively. After the mixture has been thinned, it must immediately be applied to the surface to be polished. Recommendations from experts suggest that it is best to start with larger grains, and then gradually move on to abrasive products.

Sanding or polishing?

Nowadays, when people say "grinding" and "polishing", they mean the same thing. However, these two operations have slightly different purposes, meaning they do not mean the same thing.

When talking about grinding a metal surface, it means that the surface cleanliness and its brilliance will be achieved by removing a thin layer of metal. For this, a rough grinding method is most often used. An element subjected to this method of cleaning will be really clean as a result, but it will be impossible to see a reflection in it, for example.

The polishing process removes the mostsmall surface irregularities, making it perfectly smooth. In the process of carrying out this type of work, a very small amount of metal is removed. The result that high-quality polishing will give will be so shiny that it will be almost impossible to tell the difference between it and using lapping.

Chemical polishing

The implementation of chemical polishing of the surface is carried out by the action of the solution on the metal. There it is combined with galvanic vapors, which forms a passivating oxide film on the surface of the product. As a result of using this method, you can get rid of the smallest microroughnesses on the surface of the metal, give it a shine. This happens at the same time as the top layer of the element dissolves.

It is important to note here that the quality of polishing with this method is highly dependent on how fast the film was formed and how quickly it dissolved in water. The best result, i.e. the best gloss of the metal surface, can be achieved if the minimum film thickness is reached, and this should be sufficient to prevent etching of the metal. To achieve this result, it is necessary to balance the rates of formation and washout of the oxide surface.

Electrochemical method

Electrochemical polishing is a process that reduces the surface roughness of a metal and gives it a mirror finish. In order to make this process a reality,it is necessary to place the part, which is the anode in this situation, in a bath with a substance called an electrolyte. An anode is an electrode that is connected to the positive pole of a current source. Since a second electrode is required for the polishing process, cathodes made of copper are used as this consumable item.

Since the composition of the electrolyte is selected according to a special scheme, and the conditions for the course of the entire process are also created in advance, it is possible to carry out electrochemical polishing in an uneven way. This allows you to dissolve first those places that protrude the most. This eliminates roughness while creating the perfect sheen on the metal surface.