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Bearings in Rotating Machinery: What you need to know

Although small in stature, the bearing plays a crucial role in the optimal running of rotating machinery. This makes it essential that everyone who works with such assets has a basic knowledge of their function and the best practices when it comes to maintenance and use.

To fully understand their importance its first necessary to go back to basics and detail the core reasons why bearings are used in the first place.

These are:

  • To reduce friction between moving parts
  • To reduce heat generation
  • To reduce power consumption
  • To support heavier applied loads at higher speeds with more accuracy
  • To constrain the relative motion only to the required motion.

Therefore, the health of the bearings is paramount to the running of the machinery. The following aspects are essential to ensure this:

  1. Bearings are of the proper specification to the machine and load
  2. The correct application
  3. Cleanliness
  4. Constant lubrication
  5. They work within the correct range of both speed and temperature.

Bearings are of the proper specification to the machine and load

It’s essential that the fit of the bearing is appropriate for the machinery. Each is precision-made and their fit is often to tolerances that are less than 0.001. Before employing a bearing within machinery it’s necessary to know its load rate – something that’s based on the stresses of the load and speed to which it’s subjected. The correct fitting tools should be used to mount them, and it’s vital to makes sure the bearing mountings are clean, concentric and measured precisely with a gauge or micrometre.

The correct application

Bearings are designed to have various roles and therefore created in many guises. While these might look same they have very distinct differences, making it essential that they’re only used for the task for which they’re intended – not simply because the bearing might fit.


Because bearings are machine precision components, it makes sense that they are stored and mounted in the cleanest of environments. Dirt damages bearings, leading to reduced longevity in the best case scenario, through to catastrophic breakdown in the worst. This makes it crucial to not only ensure the bearings themselves are kept clean, but that of the environment, work surfaces, and tools, as well as the hands and gloves of users.

Constant lubrication

Metal on metal requires constant lubrication. However, all lubes are not made equal – each is very specific in terms of operating temperature, viscosity, weight, additives and quantity needed. In addition, the lubrication must be untainted, therefore the correct methods of applying it to the bearings should always be adhered to.

They work within the correct range of both speed and temperature

The friction and speed applied to the bearings during use cause them to heat up. As this happens they expand. This expansion is taken into account during the design state, as the clearances within the bearing changes. This makes it crucial that the right bearing is used for the task which it’s intended, as each has its limits in speed, temperature and load.

The bearing and housing should be able to correctly disperse heat. Cooling systems should be correctly maintained, as should any lubricant reservoir.

The requirement for appropriate usage and maintenance of all parts of rotating machinery can’t be overstressed. Such good practices determine the effectiveness of the assets to carry out the tasks they’re meant to, reducing downtime and expensive, unexpected repairs.


Specialist equipment and maintenance tool supplier, Nexxis, are well aware of how costly such breaks in output can be. Their industry specialists actively work with their customers to not only supply the correct technical equipment, but with a unique flexible approach that allows for the inevitable changes in requirements that occur.

Combining this ‘flexible adaptability’ with the latest high quality equipment, full training on use and maintenance, plus packages that allow for sales, lease and hire of all our products and the ultimate in technical support has a huge impact on base line profits.

To discover how this refreshingly alternative approach can benefit your operation, call contact us now.

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