Remanufacture your bearings
29/08/2013 SKF (UK) Ltd
Even the best bearings will wear out eventually but many are being scrapped when they could be remanufactured to reduce plant costs and boost sustainability, says Phil Burge, Communication Manager for SKF.With energy an increasingly precious and expensive resource, we are all seeking ways to boost plant efficiency. To this end, the leading engineers behind today's advanced bearing technology are enabling customers to apply significant efficiency gains by remanufacturing bearings instead of replacing them.
Take, for example, the bearings that run for long hours on a paper machine. In this type of application, bearings often do not reach their potential service life because the environment in which they operate is subject to high levels of contamination. As a result, a dent created by an over-rolled hard particle will disturb the load distribution along the roller/raceway contact surface, causing stress to be locally increased, which accelerates fatigue. However, if a bearing is judged to be suitable for remanufacture, then the service life can be increased by removing such surface damage.
So how is a bearing assessed for possible remanufacture? The process begins with disassembly and cleaning. This is followed by both a visual and a microscopic inspection, a measurement of ring hardness and a dimensional inspection. The customer is then presented with a report and a recommendation for treatment.
Recommendation for reworking is categorised into classes, from Class I – Reclassification, which encompasses all of the operations of inspection described above and any appropriate additional work such as buffing, polishing, grinding of scratches and grooves, and demagnetisation, through to Class IV, with each stage adding further levels of component replacement and refurbishment to the remanufacturing process.
Any readers who may at this point be wondering if all this is worthwhile should consider the following figures: Cost-benefit analysis has shown that remanufacturing can exact a saving of as much as 80% against the cost of a new bearing. What's more, a programme of bearing remanufacture can significantly extend component lifespan and maximise efficiency if coupled with a robust predictive and preventative maintenance regime. There are also significant environmental benefits to be considered: SKF estimates that the remanufacturing of 100 kg of used bearings leads to a reduction of about 350 kg of CO2 emissions.
With this in mind, let's take a closer look at the remanufacturing process that takes place following the assessment phase. Remanufacturing can involve the grinding or polishing of bearing side faces, bore diameter and outside diameter. It may also involve the application of a nickel or chrome plating to allow the surfaces to be reground or polished to their original dimensions; this can result in a surface finish that is even better than that specified by the original blueprint. Bearings are then typically refitted with new rolling elements, while cages are inspected for cracks and potentially remanufactured by replating.
As these examples illustrate, there are many pathways to take in remanufacture, depending upon the bearing and its condition, and there are further options available where larger bearings are concerned. Here, a deeper grinding of inner and outer ring raceways, along with further machining methods such as hard turning can achieve excellent results. Superficial damage is removed by these processes, and the stressed material volume is modified.
By using a partner with expertise in bearing technology, bearings can be remanufactured to a high level of performance to offer significantly longer operating life. For example, SKF's Remanufacturing Services employ the same high-quality materials, methods and machinery to rework bearings as those that are used in the original manufacture, resulting in a remanufacturing process that significantly reduces costs and environmental impact.
In the on-going global recession, the focus of most engineering companies remains on protecting operating margins, while maintaining the quality of products and services. Options for managing costs are limited as raw material and energy prices continue at high levels, while the need to meet ever tougher environmental legislation adds to the cost base. However, remanufacturing bearings offers a new avenue by which efficiency can be enhanced and sustainability can be supported.
For further information, please contact: Phil Burge, Communication Manager, SKF (U.K.) Limited T: +44 (0)1582 496433 M: +44 (0)7770 647591 phil.burge@skf.com or visit: www.skf.com.
Print this articleShare article:
Process and Control Today are not responsible for the content of submitted or externally produced articles and images. Click here to email us about any errors or omissions contained within this article.