The Affect of Temperature, Loading and Contamination on Bearings

While modern engineering reduces the size and weight of assets, and increases their compactness, operating speed and energy-efficiency, the trade-off is higher-temperature operation. The excess heat may be generated internally – from the motor, for example – or externally from adjacent components in the same equipment or assembly.

The heat is on

When operating temperatures rise above 100°C, the effect on standard bearings can be significant. Dimensional changes can cause the bearing ring to rotate slowly in relation to its seating – which can result in scoring, noise, vibration, wear and ultimately, premature bearing failure. 

At these high temperatures, seals and lubrication also degrade rapidly. Standard Nitrile rubber seals used in deep groove bearings have a maximum operating temperature of about 110°C, and standard lubricant greases often have a similar limit.

NSK’s solution is a package of measures.

To reduce the potential for inner ring creep, NSK offers two grades of heat-treated steel which improve the dimensional stability of the bearing at elevated temperatures. X26 for operation up to 150°C, and X28 for applications up to 200°C.

Complementing these steel grades are two NSK rubber seals – made from Fluorine and Silicone – and metal shields, offering excellent performance up to 200°C.  Used in conjunction with specially-developed NSK high temperature greases (reliable up to 250°C) they ensure that however heated things get, NSK bearings keep their cool. 

Loads longer life

High radial loads reduce bearing life. So NSK has developed a range of High Performance Standard (HPS) spherical roller bearings. 

Ideal for use in aggressive loading conditions, these bearings resist seizure and wear, in spite of constant vibration, misalignment and shock loads. They maintain dimensional stability, and can support not only high radial loads but also moderate axial loads. 

Performance enhancements include extremely tight radial clearance tolerance, extra precision on the bore and outside diameter, and super-finished, specially heat-treated rollers with superior shock load capacity. 

The result is an operating life of up to twice the industry standard and up to 20% higher limiting speed.

Talking dirty

80% of premature bearing failures are the result of high contamination levels and poor lubrication. 

Contamination is introduced to a bearing system either as dry particulates or part of a fluid – usually water. These contaminants are particularly prevalent in the kind of aggressive environment found in the mineral preparation, separation and enrichment industry, and NSK has been driving innovation for machinery in the sector.  

Advances in sealing and material technologies – from high-performance DDU rubber seals to Molded-Oil solid lubrication – help to create NSK bearings which resist contamination ingress, and the spalling, flaking, wear and seizure caused by contamination damage.

If you operate machinery in an aggressive environment where temperature, loading and contamination are issues, then perhaps a little TLC– in the shape of NSK bearing solutions – won’t go amiss.