Performance Selection And Principle Of Bearing Lubricating Oil And Grease

What do we need to know when we choose bearing oil and grease for lubrication? Xinbohao told you, first of all, we need to know what kinds of bearing lubricants are. Secondly, we need to know the selection of lubricant performance. Secondly, we need to understand the principle of using bearing lubricants. Finally, we need to choose lubricants. In this way, the bearing can ensure the most reasonable lubrication effect.

Common lubricants for bearings:

Lubricating oil – liquid, the most widely used;

Grease – semi-solid, generally used for medium and low speed;

Solid lubricants are mainly used as oil and grease additives, but also can be used alone.

Performance selection of lubricating oil:

Viscosity – characterizes the internal friction resistance in a flowing liquid. Is the most important performance indicator, but also the main basis for the selection of lubricants.

Oiliness, also known as lubricity, characterizes the adsorption performance of polar molecules in oil on metal surfaces. If the oil property is good, the friction coefficient is small.

The freezing point reflects the low-temperature working performance of lubricating oil.

Flashpoint reflects the high-temperature working performance of lubricating oil.

Selection principle of lubricating oil:

1. High viscosity oil should be selected when working under high pressure or under shock and variable load conditions;
2. When the speed is high, the oil with low viscosity should be selected to reduce the friction loss;
3. When the working temperature is high, the oil with high viscosity should be selected, because the viscosity will decrease with the increase of temperature.

Performance selection of grease:

Penetration – characterizes the consistency of grease, similar to the viscosity of oil;

Dropping point – the high-temperature resistance of lubricating grease.

Selection principle of grease:

1. Working environment with water vapor, choose calcium grease;
2. High working temperature, choose sodium grease;
3. If there is water vapor and the working temperature is high, lithium grease should be selected.

Solid lubricant: in order to prevent and protect the friction surface from damage and reduce its friction and wear, the powder or film solid used on the surface is called solid lubricant. Solid lubricant is a kind of special lubricant because of its wide temperature range, strong bearing capacity, good anti-stick-slip performance, high vacuum resistance, radiation resistance, wide conductivity range, anti-corrosion, and dust prevention. Its disadvantage is that the friction coefficient is generally larger than that of lubricating grease, and the energy loss is large; It can’t cool down; The filmmaking process is complex.