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Extend asset life by remanufacturing large size and specialised bearings

24 April 2020

Instead of discarding and replacing worn components, consider remanufacturing them. This can help reduce total cost of ownership and enhance reliability, while delivering those environmental benefits that responsible companies continue to seek.

UK industry faces many challenges as it adapts to fast-changing markets, particularly those affected by the current climate of uncertainty. That old adage, ‘make do and mend’ has new resonances for companies planning for the future and who may be having difficulties deciding which is wisest in these uncertain times: to restore existing production assets or reinvest in them? Also, whether asset restoration is always the best policy, no matter what the markets may be dictating.

Regardless of how well they may be engineered and cared for in service, all rotating, reciprocating or otherwise moving mechanical components will eventually wear and will need to be replaced. Let’s take bearings as a prime example; here, the question arises: should a worn bearing be replaced by a completely new, identical one or would the better option be to recondition or repair the existing unit?

A condition-based maintenance programme will help to predict the point at which a bearing begins to exceed its specified operational parameters, giving maintenance staff the opportunity to schedule in a replacement at a time that will cause least disruption to production schedules. But then we come back to our question: to replace or repair? Both options clearly have a cost.

Where small bearings are concerned, replacement is probably best. Smaller bearings can be remanufactured, but here costs are only likely to be mitigated if large volumes of units can be remanufactured in batches. However, for medium to large or specialised bearings, the cost of remanufacturing a single unit is significantly less than the cost of a new replacement. Moreover, the amount of energy needed to complete a repair job will be considerably less than that needed to manufacture from scratch, up to 90% less, depending upon the amount of remanufacturing required. Also, larger, specialised bearings are likely to involve long manufacturing lead times should a replacement be the chosen option.

Remanufacturing is possible in over 50% of applications and it may also be possible to remanufacture a bearing, particularly older bearings, to a higher standard of quality, enabling them to perform better, and for longer, than the original part. Even more compelling, it is also possible to save as much as 80% of the cost of a new bearing by remanufacturing it rather than replacing it with a new unit.

Typical candidates for remanufacturing come from a very wide range of heavy industries and include medium to large sized bearings of most types, such as caster bearings, backing bearings, slewing bearings and railway bearings. In addition, bearing housings can be remanufactured.

There are several stages in assessing whether or not a bearing is suitable for remanufacture. First, the installation needs to be inspected to come to some understanding of why the bearing became worn or, indeed, failed in the first place. A replacement or remanufactured bearing will be subject to the same conditions on reinstatement and may suffer similar problems in service, unless the root cause of the problem is identified, and remedial action taken.

The next stage is to disassemble the bearing in order to assess the degree of damage to its component parts. A variety of specialist tools are available to facilitate this, including visual inspection and crack detection, surface hardness measurement and dimensional gauging. Ultrasound testing may be needed to detect otherwise invisible subsurface micro-cracks.

A remanufacturing expert, such as SKF, would subsequently issue a report on these detailed inspection stages, which would provide estimations of remedial work required, how long the job would take, and the costs involved. Of course, it may be judged that the bearing is beyond repair and should be recycled and a replacement advised. The remanufacturing procedure itself will be dictated by the severity of the damage and will range from simple polishing and the reuse of existing components, to the wholesale replacement of the bearing’s rolling elements and the regrinding of its raceways.

Bearing remanufacturing, especially if used in conjunction with techniques such as condition-based monitoring, can play an important role in helping manufacturers to reduce their costs, cut their carbon footprint and improve return on investment. Just as importantly, the relatively short lead times of a remanufacturing project mean that, with careful planning, bearings can be remanufactured during normal line shutdown, thereby minimising any loss of productivity.



Industry Connections: SKF (UK) Ltd

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