What to Consider When Choosing a Lubricant

The key criterion for selecting grease is the appropriate viscosity. Due to the varying properties of grease thickeners, they exhibit very different characteristics. Depending on the usage conditions, some require water resistance, others heat resistance, and some require both. Therefore, it is essential to first decide on the type and variety of grease, while also selecting the appropriate viscosity.

The base oil of grease is a primary factor determining the grease's antioxidant properties, evaporation loss, low-temperature fluidity, and lubricating performance. The temperature range for the use of soap-based grease primarily depends on the type of thickener, the grease's phase transition temperature, and its drop point; whereas the temperature range for grease with non-soap-based temperature-resistant thickeners is mainly determined by the base oil's temperature resistance, necessitating the selection of an appropriate viscosity of mineral oil or synthetic oil based on the operating temperature.

3. The viscosity index of lubricating oils greatly affects the length of soap fibers formed within grease. In practice, lubricating oils with a viscosity index of 60 to 80 are required for automotive hub bearing grease; for automotive underbody grease used in cold regions, it is necessary to use lubricating oils with excellent low-temperature performance.

4. Selecting the right grease with appropriate viscosity is crucial to form an oil film between friction parts, capable of withstanding certain loads without being extruded. Additionally, it must possess good adhesion to firmly adhere to the friction surface and not be shed by the shearing force generated by movement.

5. If the mechanical temperature is known, it is essential to select a lubricant that can reach that temperature; otherwise, severe oil shedding or loss may occur. When using at low temperatures, consider that the bearing should not generate high starting and rotational torques upon activation, and also take into account seasonal variations and other factors.

6. For lubrication points that are not regularly changed, the selected lubricating grease must have good oxidation stability, rust prevention, and mechanical stability.

7. If the friction area frequently comes into contact with water or is exposed to humid conditions, it is essential to choose a lubricant with good water resistance to prevent emulsification and loss of the lubricant or structural damage due to rapid interaction with water or moisture.

8. When grease is used in areas with a significant amount of dust or sand, it's best to opt for a thicker, harder grade (i.e., a higher viscosity number) for better sealing properties and to prevent contaminants from mixing with the friction points.

For components such as bearings with significant rotation, high viscosity naphthenic oil or mixed-base oil thickened composite soap base lubricating grease is generally preferred due to the requirement for good adhesion and vibration reduction properties.

When applying in areas where contact with chemicals or solvents is present, select a specialized lubricant.