Michelin in the fast lane for tyre recovery

Bringing old tyres back to life is big business at Michelin - it not only makes environmental sense but helps maximise customer assets, as Maxine Perella finds out

Michelin is one of the world’s most recognised brands. With 800 million vehicles on the road it’s not hard to see why: nearly a quarter of these (180 million) are equipped with Michelin tyres. Around 18 million tyres are discarded every year and with vehicle numbers projected to double over the next 20 years, the end-of-life scenario for these rubber transporters will become critical.

The reuse and recovery potential of used tyres is something Michelin takes very seriously. As a company, it recently marked 10 years of its performance and responsibility (PRM) programme which is driving CSR at all levels of the business. The PRM framework was engineered in 2002 to provide a more strategic approach to sustainability – so far, it has paid off as environmental efficiency has improved by one-third across Michelin operations over the past six years.

On a wider level, Michelin is seeking to promote the development of reuse and recovery channels for used tyres through its work with the European Tyre & Manufacturers’ Association (ETRMA). Part of this involves drawing up a European standard for products made from end-of-life tyres (ELTs) to support their classification as a by-product rather than a waste. The ultimate aim is to reclassify scrap tyre rubber as a secondary raw material.

At the company’s tyre retreading plant in Stoke-on-Trent, Michelin’s environmental & risk prevention manager Ian Cowie refers to a French term ‘valorisation’ which basically means to extract value – in this case, out of ELTs. With its global headquarters based in the Auvergne region of France, Michelin is pretty heavy on French terminology.

“Valourisation for us means getting value back out of our tyres through reuse, recycling and recovery. We look to bring old tyres back to life where we can through our retreading process here at Stoke, but where we can’t the rubber crumb is sent for shredding and reused in other markets. It is a raw material that people want,” he says.

The retreading process is a highly engineered operation and involves rebuilding worn tyre treads so they effectively ‘mirror’ new ones. Maintaining quality is critical and not every tyre that gets sent back to the site can be re-engineered in this way, so Michelin has various recovery options for those that don’t make the grade. The beauty of rubber as a material is that is 100% recoverable, either as a secondary material or as fuel.

Once broken down as crumb, rubber can be remelted and used for filling material, road surface construction, railroad track crossties and noise abatement solutions among other things. According to Cowie, the retreading process generates a lot of rubber crumb waste which can be sent on for disposal and remanufacture, but the company is constantly looking to crunch down on this.

“Our main waste stream here in terms of manufacturing is the raw uncured rubber we generate, but our workshops have reduced this a lot by implementing simple measures. We were generating 60kg of scrap rubber a day but we have cut that down to 16kg a day. By working on improving the quality of a tyre, the operators not only save waste but money too,” he explains.

Cowie’s team also targeted solvents used in rubber solutions to help adhere the rubber to the tyre as this is a hazardous waste stream. They have invested in a machine that allows the elimination of these solvents – the next objective is to eliminate solvent use from the site entirely.
Where possible, any uncured rubber generated during the re-engineering stage is put back into tyre retreads, effectively closing the loop. However due to quality issues, strict regulations apply according to Michelin’s operations manager Neil Walker.

“The process constrains us somewhat,” he says. “We set reincorporation levels that we can put some uncured rubber by-product back in with the raw material, but we need to manage this because the by-product has aging constraints and uniformity is paramount to us, it can’t have a detrimental impact on the performance of the tyre. But the main thrust is reincorporation wherever possible, that’s been a focus of the company for the past 40 years.”

Continuous improvement is part of Michelin’s culture and the company recently invested £20m to refine its retreading operations. This includes developing more energy-efficient treads as the rolling resistance of a tyre can decline by up to 30% over the tyre’s tread life. Typically, 12 to 20% of the energy in a fuel tank is transmitted as mechanical energy to turn the wheels, a third of which is consumed by rolling resistance. On average a 10% reduction in rolling resistance equates to a 1-2% reduction in fuel consumption.

Consequently, fleet operators incur significant wastage of fuel by replacing tyres prematurely. It’s an issue that Walker is trying to address as running an additional 1mm on worn tyres can result in significant fleet savings.

“Every time we take in a tyre, we x-ray it to look for metallic damage, we measure the tread and feed this information back to our marketing teams. Sometimes tyres are coming into us with just 5mm of tread gone, where they could have taken another 1.5mm off before coming back to us. It’s about managing assets better – the more tread left on the tyres, the more waste we have to throw away.”

Maximising assets can yield big returns. Back in 2009, Michelin embarked on a reverse logistics project to reduce waste disposal costs as part of its PRM drive. Here a project team of senior managers from the company’s manufacturing, logistics and commerce operations together with official retail partner ATS Euromaster implemented a nationwide scheme return all ELTs back to Michelin’s two warehouse operational hubs for sorting and onward disposal.

Numerous benefits resulted from this, not least reducing disposal costs by a seven-figure sum. Less scrap is now stored at ATS outlets due to more frequent collections, and there have also been marginal cost improvements from maximising group assets. In addition, all scrap tyre is handled by members of the Tyre Recovery Association, who are audited by the Responsible Recycler Scheme.

Maxine Perella is Waste Market Editor at edie

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