Grease Classification
Grease Classification
2022年3月19日
Rust Prevention Method
Rust Prevention Method
2022年3月19日

Lubricating Oil Composition

Lubricating oil is generally composed of base oil and additives. Base oil is the main component of lubricating oil, which determines the basic properties of lubricating oil. Additives can make up for and improve the performance of base oil and give some new properties. They are an important part of lubricating oil.Lubricating Oil Composition

A. Lube base oil,Lubricating Oil Composition

For example, Huyou base oil is mainly divided into mineral base oil and synthetic base oil. Mineral base oil is widely used and used in a large amount (more than 95%), but in some applications, the products prepared by synthetic base oil must be used, so the synthetic base oil has developed rapidly. Mineral base oil is refined from crude oil. The main production processes of lube base oil include atmospheric and vacuum distillation, solvent deasphalting, solvent refining, solvent dewaxing, clay or hydrorefining. In 1995, the current standard of lubricating base oil in China was revised, the classification method was mainly modified, and two special base oil standards of low pour point and deep refining were added. For the production of mineral lubricant base oil, it is important to select the crude oil.Lubricating Oil Composition

The chemical composition of mineral base oil includes high boiling point, high molecular weight hydrocarbon and non hydrocarbon mixture breaing. Its composition is generally alkanes, cycloalkanes, aromatics, oxygen-containing, nitrogen-containing and sulfur-containing organic compounds, colloids, asphaltenes and other non hydrocarbon compounds.

B. Additive

Additives are the essence of modern high-grade lubricating oil. Correct selection and reasonable selection can improve its physical and chemical properties, endow lubricating oil with new special properties, or strengthen its original properties to meet higher requirements. According to the required quality and performance of lubricating oil, careful selection, careful balance and reasonable allocation of additives are the key to ensure the quality of lubricating oil.Lubricating Oil Composition

 Commonly used additives include: viscosity index improver, pour point reducer, antioxidant, detergent dispersant, friction moderator, oily agent, extreme pressure agent, antifoam agent, metal passivator, emulsifier, anti-corrosion agent, antirust agent and demulsifier.Lubricating Oil Composition

(1) Hydrocracking is a refining process of class III base oil introduced in China in recent years. The exact term “hydrocracking” should be called “hydroisomerization” technology, which is also an advanced technology for refining base oil in the world. From the perspective of technological development, lubricating oil hydrogenation technology has experienced hydrofining, hydrocracking and catalytic dewaxing. At present, it is an advanced hydroisomerization process. Hydrofining only removes sulfur and nitrogen from the base oil and saturates some aromatics to improve the oxidation stability of the base oil. Hydrocracking has two functions of hydrogenation and cracking, which not only improves the oxidation stability of the base oil, but also improves the low-temperature fluidity of the base oil.Lubricating Oil Composition

Lubricating Oil Composition

Hydroisomerization enables the selective reaction of n-alkanes and transforms valuable wax with high viscosity index into isomeric alkanes with high viscosity index and excellent low-temperature performance, so as to give new performance to lubricating products. The base oil can meet the API (American Petroleum Institute) class II and III oil standards.

Using this technology can more effectively remove all kinds of chemical impurities in ordinary mineral oil, especially high-pressure hydrogenation, reconstruct the molecular structure, and greatly increase the proportion of components conducive to improving the performance of oil products, such as branched alkanes, so as to improve the performance state of base oil. The base oil made by “hydrocracking” technology has low volatility, higher viscosity index, good low-temperature performance and further improved oxidation stability.Lubricating Oil Composition

In 2004, uni president introduced hydrocracking class III base oil to mix and produce engine oil, which comprehensively upgraded the quality of engine oil in China, that is, the “hydrogenation storm” referred to in the media, made up for the gap that China could not prepare engine oil of corresponding quality due to the absence of class III oil, and made the high-end engine oil of domestic engine reach or exceed the imported engine oil, which is of far-reaching significance.Lubricating Oil Composition

(2) What is the difference between mineral oil and synthetic oil?Lubricating Oil Composition

Lubricating oils for various purposes are prepared by mixing base oils with different grades of viscosity and several additives in different proportions. The main difference between mineral oil and synthetic oil lies in the difference of base oil. The base oil of mineral oil is refined from the residual tower bottom oil after fractionating useful light substances (such as aviation oil, gasoline, etc.) in the process of crude oil refining. In essence, it uses the poor components in crude oil. There are thousands of different mixture molecules in crude oil. Even if the refining technology is refined, it can not remove all the bad substances and impurities. In contrast, the base oil of synthetic oil is ethylene and propylene dispersed from gas or natural gas in crude oil, and then refined into a base liquid composed of macromolecules through complex chemical reactions such as polymerization and catalysis.Lubricating Oil Composition

 In essence, it uses the better components in crude oil, which are chemically reacted and achieve the expected molecular morphology through artificial control. Its molecules are arranged neatly and have a strong ability to resist external variables. Therefore, synthetic oil has a better constitution, and its ability to thermal stability, antioxidant reaction and viscosity change is naturally much stronger than mineral oil. In addition to the above, the mineral oil cannot completely remove the impurities contained in the refining process, so the flow point is high and is not suitable for cold zone operation. Synthetic oil contains no impurities, and its flow point can be below – 50 ℃ If there is a great difference in climate and temperature in aircraft, spacecraft, submarines and other occasions, synthetic oil must be used.Lubricating Oil Composition

(3) What is the difference between single-stage engine oil and multi-stage engine oil?

As we have already introduced, the viscosity of engine oil plays a very important role in the lubrication protection of engine parts. Temperature is closely related to viscosity. Usually, when we decide the viscosity of engine oil, we will consider two different environments: low temperature and high temperature. When the engine is at low temperature (that is, when it is cold), we need thinner and lower viscosity oil for lubrication; Because if the oil is too thick and the viscosity is too high, it will not flow completely and freely, resulting in insufficient lubrication. On the contrary, when the engine reaches high temperature (that is, after the hot car), we need oil with high viscosity to lubricate and protect the engine parts; Because if the viscosity is too low at this time, it will also cause engine damage due to insufficient lubrication. Therefore, the general single-stage engine oil may meet the requirements at low temperature, but with the operation of the engine and the gradual increase of the ambient temperature, its viscosity will continue to decrease, so it can not achieve lubrication. Vice versa, if only considering the viscosity at high temperature, it will not meet the low temperature environment. However, multi-stage oil is different. Although in a wide range of temperature changes, its viscosity change rate is not very large, so it can meet the viscosity requirements that it will not be too thick at low temperature and too thin at high temperature, so that the engine can be fully lubricated and protected.

(4) What are the benefits of using synthetic oil? Can it extend the oil change mileage?

First of all, let’s review the advantages of synthetic oil over mineral oil in properties. It has good thermal stability and oxidation stability, cold start fluidity, wear protection and fuel saving performance (at the same viscosity level). Therefore, basically, when we use synthetic oil, we can get the following benefits:

1. Engine speed increases

2. The engine sound goes down

3. The engine oil is not easy to deteriorate and there is no sludge

4. Save fuel

5. Extended engine life

Lubricating Oil Composition

Impact on vibration and noise:

Influence on Vibration: NSK bearing test results show that cleanliness seriously affects the vibration level of rolling mill bearing, especially the vibration in high frequency band. The bearing with high cleanliness has low vibration speed, especially in high frequency band.The Cleanliness of NSK Bearing is Important to Heating

c. Effect on lubrication performance:The Cleanliness of NSK Bearing is Important to Heating

The decline of NSK bearing cleanliness will not only affect the formation of lubricating oil film, but also cause the deterioration of lubricating grease and accelerate its aging, which will affect the decline of lubricating performance of lubricating grease.The Cleanliness of NSK Bearing is Important to Heating

Under popular conditions, the filling amount of NSK bearing grease always exceeds the practical demand of direct intervention lubrication, fills the cavity on the holding frame and the bearing cover of the rolling mill, and forms a contour on the periphery of the rolling element. During this process, the bearing temperature rises rapidly due to the resistance of excess grease. Although most of the excess grease is squeezed out at the initial stage of operation, and the grease squeezed in the accessories of the raceway may still be migrated and transformed into the rolling element and brought into the raceway.

In the initial stage of rolling mill bearing operation, most of the lubricating grease is quickly squeezed out of the raceway (less than one minute), and the accumulated lubricating grease is discharged in a small amount one after another in the cycle of bearing migration and transformation.

At this time, the bearing temperature continues to rise until all the excess grease is discharged, which can be called the running in stage of grease.

According to the quality and filling amount of grease in the bearing structure of the rolling mill, this period may last for more than ten minutes or even several hours.

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