What are the performance indicators of grease?

With the rapid development of science and technology, greases are constantly being updated. In the 1950s and 1960s, the first generation of greases: calcium-based grease and sodium-based grease were used; in the 1970s and 1980s, the second-generation greases were used: lithium-based grease, complex aluminum-based grease, and lithium complex-based grease. In the past 20 years, various countries have successively developed high dropping point greases. There is a urea-based grease that is better than lithium-based grease in all aspects. The proportion of urea-based grease application can measure the level of industrial development of a country in the 21st century.

Grease is composed of base oil, thickener and additives. The properties of grease are determined by its composition and structure.

Base oils are divided into two categories: mineral oil and synthetic oil. About 85% to 93% of the world's grease market is mineral oil grease.

Thickeners determine a range of properties of grease. Divided into four categories: soap-based, hydrocarbon-based, organic and inorganic thickeners. Soap base: mainly fatty acid metal salts; hydrocarbon-based thickeners are mainly paraffin and ozokerite, commonly known as petroleum jelly; inorganic thickeners include bentonite, silica gel, boron nitride and carbon black; organic thickeners mainly include: amide, polyurea , fluorocarbon, etc.

In addition to the base oil and thickener, a third component—additives—is often added to the grease composition to improve certain properties of the grease. Such as: scaling improvers, antioxidant additives, anti-rust additives, anti-wear and extreme pressure additives, etc.

Cone penetration - is an indicator to measure the consistency of grease. The larger the value, the softer the fat, and vice versa.

The cone penetration is the depth at which a cone of a certain mass is released from the cone penetration meter at 25°C and the cone falls into the sample to be measured within 5 seconds. According to the degree of cone penetration, grease is divided into 9 grades.

Working cone penetration is the first indicator to be considered when selecting grease. Usually based on the working conditions of the friction parts and the method of filling grease. to select the appropriate grease consistency.

For general rolling bearings, when the speed factor DN value (bearing inner diameter mm × rotation speed r/min) is 15000~30000, choose No. 2 grease or No. 1 grease; if the DN value is greater than 30000 but less than 50000, choose No. 3 grease Grease is more suitable; if centralized grease supply lubrication is used, No. 0 grease or No. 1 grease is more suitable; in some gearboxes, No. 00 or No. 000 or even thinner grease is more suitable.

Dropping point

The grease is heated under specified conditions, and the grease softens as the temperature increases. The temperature of the first drop dropped from the grease cup is the dropping point. The dropping point of a grease is a rough measure of its maximum operating temperature. Generally speaking, the maximum operating temperature limit of grease should be 30~50℃ lower than its dropping point. However, for low-speed use, the maximum operating temperature limit of grease can be 15~30°C lower than the dropping point.

It should be noted that the dropping point is not the only parameter that determines the maximum operating temperature limit of a grease. To determine the maximum operating temperature limit of a grease, in addition to the dropping point, you should also refer to parameters such as the consistency of the grease at high temperatures, the antioxidant capacity of the base oil and thickener, and the colloid stability at high temperatures.