Selection and management of grease

Conditions of use of grease

    There are many types and grades of grease with different performances. In order to make the mechanical parts lubricate well, it is very important to choose the grease reasonably. The following factors must be considered when selecting the grease:

  • The function of the grease is required, whether it is lubrication or protection.

    • Temperature, load, speed and lifetime of lubricated parts.

• Centralized pump lubrication, regular grease or use without replacement for a long time.

• Whether the working conditions are intermittent or periodic, with or without shock load and vibration.

    • Whether the ambient temperature and humidity are in contact with corrosive media.

    The main factors are the four aspects of working environment conditions, temperature, operating speed and load. They have a greater impact on grease in use. The main purpose of selecting grease is to be able to use it for a long time to ensure the normal lubrication of the equipment.

    (1) Temperature

    The temperature conditions and the magnitude of changes in the bearing or friction parts have a significant effect on the lubrication and service life of the grease.

    Grease is a colloidal dispersion system. Its plasticity and similar viscosity change with temperature. When the temperature rises, the base oil of the grease will evaporate, oxidize and deteriorate, and the colloidal structure of the grease will change to accelerate the oil separation. When the temperature reaches the melting point of the grease thickener or the critical point at which the thickener fiber skeleton sustains the base oil, the colloidal structure is completely destroyed and the grease cannot be used further. If the temperature changes are large and the temperature changes frequently, the phenomenon of gel shrinkage and oil separation will be more serious. In general, the main causes of high temperature grease failure are due to gel shrinkage and evaporation of the base oil. When the base oil loss reaches 50% to 60%, the grease loses its lubricating ability.

Generally, the higher the temperature, the shorter the service life of the grease. The relationship between the service temperature and the service life of most greases is that when the bearing temperature reaches a certain value, the service life of the grease decreases by 1/2 every time the temperature rises by 10 ° C to 15 ° C.

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