What to take into consideration when greasing your electric motors.

Viscosity refers to the measure of a fluid’s resistance to flow. It determines how thick or thin a fluid is? When a fluid has high viscosity, it flows slowly, while a fluid with low viscosity flows more quickly. In the context of grease for electric motor bearings, viscosity is an important property because it affects how well the grease can flow into the bearing and provide lubrication to the moving parts. The appropriate viscosity of grease depends on factors such as operating temperature, speed, load, and the size of the bearing.

Consistency– what is the grease consistency for electric motor bearings? It depends on factors such as operating conditions, bearing type, speed, load, and temperature range. Proper consistency ensures that the grease stays in place within the bearing, provides adequate lubrication, and protects against wear and friction. A good reference is National Lubricating Grease Institute (NLGI) grade, which ranges from 000 to 6. Generally, NLGI 2 grade greases are used in electric motor applications involving horizontal shaft configurations, while NLGI 3 grade greases may be more appropriate for motors supporting vertical shaft configurations.

Oxidation resistance – Lubricants with good oxidation resistance are formulated to withstand these high-temperature conditions and resist the formation of harmful oxidation by-products. They maintain their viscosity and lubricating properties over extended periods, thus helping to prolong the life and efficiency of electric motors. You can find additional resources under American Society for Testing Materials (ASTM) high temperature grease life test results give a good indication of oxidation resistance when operating under extreme conditions.

Anti-wear – are specifically formulated to form a protective film or boundary layer between contacting surfaces, reducing metal-to-metal contact and minimizing wear. By using such grease you can create a protective barrier on metal surfaces, reducing friction and preventing the formation of wear particles.

Dropping point– corolates with the temperature at which the grease undergoes a significant change in consistency. More precisely, it’s the temperature at which the grease changes from a semi-solid or solid state to a liquid state. The dropping point of grease used in electric motors indicates its thermal stability and suitability for high-temperature applications, helping to ensure reliable lubrication and extended motor life.

Shear Stability – because of various moving parts such as bearings, gears, and shafts are subjected to mechanical stress and frictional forces. These forces can cause the lubricant to undergo shear, where it experiences a change in viscosity or consistency due to the deformation of its molecular structure. It is is crucial for ensuring effective lubrication and optimal performance of electric motors by minimizing wear, reducing friction, and preserving energy efficiency throughout the motor’s operational life.

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