SKF India Blogs

Bearing Remanufacturing: The efficient way to make your bearings work more for you

Bearings are at the heart of all machines with rotating applications, and take a lot of punishment due to uneven forces generated inside the machine under practical operating conditions.

However, under correct lubrication conditions and actual applied loads being under the bearing’s stress fatigue limit, bearings should last beyond their predicted life.

Bearing life is considered as the period until the first sign of fatigue appears. The bearing life is the function of the number of revolutions performed by the bearing and the magnitude of load applied. Fatigue is the result of shear stresses cyclically appearing immediately below load carrying surface of the ring and rolling elements.  After a time, these stresses cause cracks underneath the surface that gradually extend to the surface.

Wear, rust, indentations, microcracks and certain application conditions – like contamination or sporadic metal–to-metal contact in the rolling contact zone - are the major reasons of damage to the bearings. As a result, the service life of a bearing is often shorter than the calculated rating life.

During operation a lot of stresses get developed under the subsurface area of raceways.

Usually bearings are either replaced during planned maintenance when nearing the end of their operation life or after unplanned breakdowns. Depending on the bearing type, replacement can be expensive and may take long time to repairs, hampering the manufacturing cycle time.

Naturally it may have negative impact on a company’s profitability.

Which leads us to the question - How we can increase the service life of bearings in order to decrease downtime, reduce costs and scrap?

The market trend shows that people are going for cheaper make of bearings to reduce the cost but this is not a long term solution. The real, sustained solution lies in a systematic approach with Remanufacturing of bearings.

A controlled remanufacturing process before the occurance of any major damage or bearing failure occurs, can substantially extend the service life of the bearing in question, reducing costs and lead times. And since it requires less energy than manufacturing a new bearing, it is better for the environment as well. A controlled remanufacturing process means having controlled measurements, specific tools for grinding and polishing by trained personnel, apart from having all internal components checked thoroughly by competent personnel.

Most importantly, Remanufacturing is not only "rework to original specifications", it can in fact be an improvement. For instance; at extremely low operating speeds, in applications like casters,  "Aggressive Polishing" improves the service life of the bearing. The slightly rougher raceways make it easier for lubricants to hold on to it so that the lubricating film is continued and keeps the metal parts seperated from each other. As a result, the stresses also get reliveived during remanufacturing.

An extensive damage statistics analysis by SKF gives indications for corrective actions, e.g. change to a different lubricant, improvement in the sealing arrangement, balancing or alignment.

With systematic approach we can use the same bearing up to three times at an average, with changing of new loads.

The cost benefit analysis shows that potential cost savings of between 50% to 80% of the cost of a new bearing can be achieved by remanufacturing – depending on bearing size / type and the bearing condition.

Apart from the cost benefits mentioned above, the Remanufacturing process also reduces CO2 emissions. In fact, remanufacturing 100 kgs of used bearings leads to a reduction of about 350 kg of CO2 emission. In todays’s age, when going green and reducing carbon footprints has become excessively important, this kind or reduction in carbon footprints is exactly what the customers are looking for.

Additionally, Bearing Remanufacturing is a green process requiring minimal energy input and thus significantly reducing raw material consumption when compared to manufacturing of new bearings.

All these factors make a strong business case for customers to consider Bearing Remanufacturing as a viable process to be included in their machine life cycle, to save costs effectively and imporve operational efficiency and performance.
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