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Remanufacturing cuts lifecycle costs and environmental impact

Remanufacturing cuts lifecycle costs and environmental impact

In the correct circumstances, repairing – or remanufacturing – a failed bearing makes more economic and environmental sense than replacing it with a new one, as the experts at SKF explain.

Ordinarily, when a component such as a bearing fails, it is automatically replaced with a new one. The old bearing is then disposed of. While this process is more sustainable than it was, thanks to improved recycling processes, it still makes for a lot of bearings.

There is now increasing focus on the concept of remanufacturing, in which a bearing is repaired rather than replaced. This does not work in all circumstances: very small bearings – such as those in an electric motor – cannot be repaired and replaced economically, for instance. However, other types – even those as small as a spherical roller bearing – can be remanufactured, from both an economic and ecological standpoint.

Remanufacturing can reduce the life cycle cost of industrial equipment by extending its operating life and reducing maintenance costs. It also helps companies reduce consumption of natural resources and energy, to lessen their environmental impact – which is increasingly important in both society and industry.

Many factors – from poor lubrication to contamination – can reduce the service life of a bearing. Rusting, indentations and microcracks can all cause expensive bearing failure. However, if a problem is identified early enough – before irreparable damage occurs – the bearing can be removed, remanufactured and returned to ‘factory condition’.

Remanufacturing is not always the most appropriate approach, and this will be picked up when the bearing is inspected. Bearings that have suffered heavy damage, fractures or sub-surface initiated fatigue should be replaced. This is because the damage is too serious to repair. However, bearings that have suffered some form of surface-initiated fatigue can often be restored using techniques such as honing or grinding.

Many other types of bearings lend themselves to remanufacturing, as long as the damage is not too serious. The remanufacturing process is typically more appropriate in heavy industries, such as metals, mining, cement, pulp and paper, and marine.

In a real-world example, the operator of a coal-fired power station found that six wheel bearings needed overhauling to bring a pulverizer back online. The pulverizer is critical to maintaining peak power output.

The cost of new bearings was around €17,000, with a lead time of around seven months. Remanufacturing the bearings took six weeks, and cost around €11,000. This led to a direct saving of around €6,000 in new bearing purchases and related costs. More importantly, the faster repair avoided more than five months of potentially reduced power production – which would have led to €1 million in lost revenue.

Remanufacturing process

Remanufacturing may be seen as a ‘slower’ option than replacement – as a part must be disassembled, shipped for repair, then returned and reinstalled. However, the process can be relatively fast. In one case, SKF remanufactured a large bearing for a paper manufacturer inside 10 days. Often, these short lead times can be contained within normal line shutdowns – so there is no loss in productivity. In some cases, remanufacturing can be completed in a few hours.

Work begins with cleaning, degreasing and disassembling bearings. All components are then inspected. Then, a detailed bearing analysis report is issued. Those bearings that are not damaged beyond repair can be restored using appropriate procedures – including polishing, grinding and component replacement. As a rule of thumb, any bearing with more than 30% of its calculated service life remaining is worth remanufacturing. For this reason, the cost savings that can be generated through remanufacturing are substantial.

There are several advantages to remanufacturing – and the most significant one is cost. It is normally much cheaper to repair a damaged bearing than it is to install a new one. This helps manufacturing plants retain more of the investment in their existing bearings. Overall, remanufacturing can deliver cost savings of up to 50% compared to manufacturing a new bearing.

At the same time, a remanufactured bearing consumes around 10% of the energy of a new bearing. It can also deliver an 80% reduction in CO2 emissions. This improvement in sustainability is critical in the modern manufacturing environment. There are also associated savings in resources (no need for new steel, for instance) and waste.

At the same time, remanufacturing breathes new life into a bearing, helping to extend operating life beyond its original expected lifespan. The process can add 50% or more to the useful life of a bearing. Remanufacturing can actually be carried out more than once – if the type of damage allows it – which can further extend bearing life.

Linked to this, the process can increase the uptime of a production line by boosting asset reliability. A remanufactured bearing will also be supplied with a warranty for the components and workmanship. Remanufacturing also brings associated benefits, such as reduced maintenance costs.

Once remanufacturing has been carried out, it is important to prevent the original damage from happening again. This can be done by using predictive maintenance, which provides information about the ongoing status of plant machinery using techniques such as vibration analysis. Suppliers can offer root-cause failure analysis to identify the reasons behind bearing damage – and devise a ‘corrective action’ plan to stop problems from returning.

 

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