What is the important role of the coating on the oil film bearing?

Nov 13, 2024

The coating on the oil film bearing plays a vital role in industrial production. Oil film bearings are common key components in mechanical equipment and are widely used in rolling mills, internal combustion engines and other equipment. It reduces friction and wear by forming a thin layer of oil film, thereby improving the operating efficiency and reliability of the equipment. However, with the increase in equipment load and speed, the performance requirements for oil film bearings are also getting higher and higher. Therefore, plating a layer of special materials on the surface of oil film bearings has become an important means to improve bearing performance.

The role of coating

1. Improve corrosion resistance

Oil film bearings operate in harsh working environments and are often corrupted by moisture, salt, acid and alkali substances. These corrosive substances will damage the surface of the bearing, resulting in a decrease in bearing performance and even premature failure. By plating a layer of materials with excellent corrosion resistance, such as nickel, chromium, etc., on the surface of the bearing, a protective film can be formed to effectively block the erosion of corrosive substances, thereby improving the corrosion resistance of the bearing.

Specifically, the coating can prevent the residual moisture, salts and certain compounds in the lubricating oil from oxidizing to form organic acids and peroxides, which will accelerate the corrosion process of the bearing. At the same time, the coating can also prevent the fuel in the oil and its combustion products from penetrating the bearing, further protecting the bearing from corrosion. For example, in the sliding bearing of an internal combustion engine, the coating can significantly improve the corrosion resistance of the bearing and extend its service life.

2. Improve wear resistance

During the high-speed operation of the oil film bearing, the surface will be subjected to strong friction and wear. This wear will not only reduce the accuracy and performance of the bearing but also accelerate the failure of the bearing. By coating the surface of the bearing with a layer of materials with excellent wear resistance, such as cemented carbide, carbide, etc., the wear resistance of the bearing can be significantly improved.

The coating can form a hard protective layer and reduce the direct contact between the bearing surface and the friction pair, thereby reducing the friction coefficient and wear rate. At the same time, the coating can also effectively prevent cracks and peeling caused by wear on the bearing surface, further improving the reliability and durability of the bearing. For example, in rolling mill oil film bearings, coatings can significantly improve the wear resistance of bearings and extend their service life.

3. Improve anti-seizure performance

Under heavy load and low-speed conditions, oil film bearings are prone to seizure, that is, adhesion between the bearing surface and the friction pair due to friction. This phenomenon can cause poor operation of the bearing, temperature rise, and even failure. By coating the bearing surface with a layer of material with excellent anti-seizure performance, such as soft metals or alloys such as copper and lead, the occurrence of seizure can be effectively prevented.

The coating can reduce the friction coefficient and adhesion between the bearing surface and the friction pair so that the bearing can maintain a good lubrication state during operation. At the same time, the coating can also absorb and disperse the heat generated by friction, reduce the operating temperature of the bearing, and further improve the anti-seizure performance of the bearing. For example, in internal combustion engine sliding bearings, coatings can significantly improve the anti-seizure performance of the bearing and improve its operating stability under heavy load and low speed conditions.

4. Improve compliance and embedding

Oil film bearings need to withstand complex loads and deformations during operation. By plating a layer of material with excellent compliance and embedding properties, such as lead-tin alloy, on the surface of the bearing, the compliance and embedding properties of the bearing can be significantly improved.

The plating can absorb and disperse the stress caused by load and deformation on the surface of the bearing so that the bearing can maintain a good contact state and lubrication state during operation. At the same time, the plating can also effectively prevent cracks and peeling caused by stress concentration, further improving the reliability and durability of the bearing. For example, in the rolling mill oil film bearing, the plating can significantly improve the compliance and embedding properties of the bearing so that it can better adapt to complex working conditions.

5. Improve fatigue strength and load-bearing capacity

The oil film bearing will be subjected to periodic loads during long-term operation and is prone to fatigue damage. By plating a layer of material with high strength and good toughness, such as high-strength alloy, on the surface of the bearing, the fatigue strength and load-bearing capacity of the bearing can be significantly improved.

The plating can enhance the fatigue resistance of the bearing surface so that it can better withstand the effects of periodic loads. At the same time, the plating can also improve the overall strength and stiffness of the bearing so that it can better withstand the effects of heavy loads and impact loads. For example, in the sliding bearings of internal combustion engines, the coating can significantly improve the fatigue strength and load-bearing capacity of the bearings and extend their service life.

6. Reduce energy loss

The oil film bearing will generate certain friction loss and energy loss during operation. By coating the bearing surface with a layer of smooth and wear-resistant materials, such as metals or alloys such as chromium and silver, the friction loss and energy loss on the bearing surface can be significantly reduced.

The coating can reduce the friction coefficient and contact area between the bearing surface and the friction pair, thereby reducing friction and friction loss. At the same time, the coating can also improve the smoothness and precision of the bearing surface so that it can better adapt to the formation and maintenance of the lubricating oil film. All of these help to reduce energy loss and improve the efficiency of the entire system. For example, in the rolling mill oil film bearings, the coating can significantly reduce energy loss and improve the production efficiency and economic benefits of the rolling mill.

Types and selection of coatings

The types of coatings on oil film bearings are varied, including metal coatings, alloy coatings, hard coatings, etc. When choosing the appropriate type of coating, the following factors need to be considered:

The working environment of the bearing, including temperature, humidity, corrosive substances, etc. These factors affect the corrosion and wear resistance of the coating.

Bearing load and speed: Heavy-loaded and high-speed bearings need to have higher strength and wear resistance. Therefore, these factors need to be considered when choosing the type of coating.

Bearing material and precision: Bearings of different materials and precisions have different requirements for coatings. For example, high-precision bearings need to have better surface quality and precision retention.

Economic efficiency: The cost of the coating is also one of the factors that need to be considered when choosing. It is necessary to reduce the cost as much as possible while ensuring performance.

Commonly used coating types include nickel, chromium, silver, gold, palladium, tungsten and other metals and their alloy coatings. These coatings have different properties and characteristics and can be selected according to specific application requirements. For example, chrome plating has the characteristics of high hardness, good wear resistance and strong corrosion resistance; silver plating has the characteristics of good conductivity, good thermal conductivity and high reflectivity.

In summary, the coating on the oil film bearing plays an important role in improving bearing performance, extending service life and optimizing overall system efficiency. By selecting the appropriate coating type and processing conditions, the corrosion resistance, wear resistance, seizure resistance, compliance and embedding resistance, fatigue strength and load-bearing capacity of the bearing can be significantly improved. At the same time, the coating can also reduce energy loss and improve the efficiency of the entire system. Therefore, when designing and manufacturing oil film bearings, the role and selection of the coating should be fully considered to ensure that the performance and reliability of the bearing meet actual needs.