a. When choosing grease, temperature (working temperature and ambient temperature) is an important factor. Liquid loss and liquid shrinkage caused by high temperature are the main reasons for the high temperature failure of grease. If the working temperature is close to or exceeds the dropping point of grease, it will cause the deterioration of grease, evaporation of mineral oil, oil separation and loss; and at low temperatures, The starting torque of the machine is extremely large, and it is often difficult to start, so the minimum temperature of the grease must be considered.

    Therefore, when using it at a higher temperature, a grease with a cone penetration and high temperature resistance should be used. Such as sodium-based grease, lithium-based grease, compound calcium-based or compound aluminum-based grease, bentonite grease, silicone oil compound calcium-based grease and so on.

    The temperature of general grease should be 10~20℃ lower than the dropping point (synthetic grease should be 20~30℃ lower than the dropping point). When working at low temperature (-20~-60℃), generally use grease with low viscosity mineral oil with proper penetration and good low temperature performance, such as No. 2 low temperature lithium base grease, ester oil-lithium Base grease, silicone oil compound calcium base grease, etc.

　　B. The degree of cone penetration of the load grease is related to the ability to bear the load during use. Greases with a small cone penetration can bear larger loads than those with a large cone penetration.

    Therefore, on the friction surface that bears heavy load or shock vibration load, grease with small penetration should be selected; on the friction surface with light load, grease with large penetration can be selected. On the friction surface working under boundary lubrication conditions, grease with extreme pressure additives should be selected.

　　C. Due to the poor heat dissipation of the grease, the shaft temperature of high-speed bearings is likely to rise, so grease with a large penetration should be selected from low-viscosity lubricants. On the contrary, for the friction parts running at low speed, grease with a small penetration should be used.

　　D. Environmental conditions The working environment of mechanical friction parts is also closely related to the application of grease. In the wet working environment or in places where there is a lot of contact with water, in order to prevent the washing of water and the mixing of moisture and steam into the grease to emulsify and deteriorate the grease, calcium-based grease, lithium-based grease and aluminum-based grease with strong water resistance should be selected However, sodium-based grease cannot be used because of poor water resistance and easy emulsification.

     In the occasions where water acid gas and other corrosive gases are more serious, grease or hydrocarbon-based grease with anti-corrosion additives should be selected. The chemical stability of hydrocarbon-based grease is better than soap-based grease. In the case of heavy dust, thick grease containing graphite can be used.

　　③Select according to the conditions of use of grease:

　　 For the grease used in the centralized lubrication system, in order to facilitate the transportation, the grease with larger penetration and better pumpability should be selected.

    In order to reduce consumption and prolong the service life of the grease, it is generally necessary to select a grease with good stability during use and storage, no layering of oil soap, good viscosity-temperature performance, and no corrosion to mechanical parts.