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BEP’s steel and copper roll recycling/refurbishing service returns used or damaged chill rolls used in the plastics and lamination industries to their original finish and concentricity specifications.

The service is said to offer potential capital cost savings, production efficiency benefits and environmental benefits for manufacturers.

It can cost up to GBP30,000 to replace a large steel cooling roll and GBP60,000 for a new copper shelled chill roll, according to BEP, who refurbishes rolls of all sizes up to 1,500mm diameter and 10 tonnes in weight.

Refurbishment charges can amount to less than 30 per cent of the cost of purchasing a new roll from an OEM.

On large copper-shelled rolls, refurbishment can save over 80 per cent against new ones.

Precision rolls used in plastics-manufacturing processes generally work in sets of three and, because they can run with only microns separating them, concentricity is critical.

Coater rolls used in laminating processes require similarly fine tolerances.

BEP’s techniques guarantee maintenance of the structural integrity of rolls and repeatability of the original chrome finish, Ra (Roughness average) and TIR (Total Indicator Reading) specifications and tolerances to ensure that rolls work first time on reinstallation.

Another benefit is the reduction in down time, as refurbishment is considerably quicker than buying new.

BEP undertakes all the necessary processes in-house and can refurbish a roll in 15 working days, compared with 90 days for the manufacture of a new roll.

The extended lead time for new rolls is due in part to the availability of the special steels required for the manufacture of roll components.

Surface finish is a key performance factor for any roll and the company claims that it can replicate any surface, having developed its skills creating ultra-high-quality finishes for photographic papers.

In effect, the refurbishment service offered by BEP is a sustainable, closed-loop recycling system that helps to protect the environment by taking good worn or damaged products and returning them for use in their original application.

Refurbishment involves several processes.

Initially, rolls are inspected at the company’s manufacturing facility in Radcliffe, Manchester.

Reports detailing what work is required to bring them back to specification are prepared and, following agreement with the customer, various treatment steps are undertaken.

To restore rollers to their original thermal efficiency, internal waterways are cleaned with a temperature-controlled acid solution to remove corrosion.

Over time, waterways on cooling and heating rolls may becoming furred up with lime scale or rust.

Providing the waterways are not completely blocked and the rust has not corroded through the roll shell, they can usually be cleaned.

After cleaning, any residual acidity is neutralised and the roll is thoroughly washed out with water and flushed with a rust inhibitor.

Rolls are then chromium plated to hardnesses of between 900 and 1,150HV, which are retained up to 400C.

The finish also resists tarnishing above 300C and provides low co-efficient of friction, high resistance to wear and abrasion, plus resistance to most chemicals.

However, these characteristics can only be delivered consistently if the chrome is of the highest possible purity and, to achieve this, BEP has developed its own custom-designed high-level-purification plant.

At this stage, the company may also recommend that any roll operating above 30C be de-gassed.

The chrome-plating process introduces approximately 0.06 per cent hydrogen into the finish and, incorrectly managed during production, this can cause defects in the form of tiny bubbles that can result in reject product.

Although the gas disperses naturally during production, manufacturers can waste production time by pre-heating rollers in their machines to minimise the effect.

Alternatively, rolls can be de-gassed to remove occluded hydrogen from the chrome deposit.

The process involves heating rolls in a specially constructed, temperature-controlled oven to a precisely controlled thermal ramp.

To eliminate the risk of distortion, BEP hangs rolls vertically.

All temperature profile data is recorded.

Additional finishing work might also include a nickel coating under the chrome finish to provide corrosion protection to the steel or copper shell.

In every case the roll can be brought back to original size with copper or nickel as required.

Even rolls that have suffered indentations can be repaired.

Before the roll is re-surfaced to its original specification, impressions of the original surface will have been previously taken and analysed.

In-house techniques enable BEP to produce high-quality, mirror-polished, chrome-plated rolls with surface finishes as fine as Ra (Roughness average) 0.005um and with TIR and parallelity close to perfection, it claims.

Paper manufacturers and laminators typically require ultra-finish chrome rolls.

A range of matt, silk and various textured surfaces can also be produced by shot blasting and electrolytic techniques creating finishes from fine Ra 0.1um to rough Ra 15um.

Finally, if required, roll bearing journals can be restored to their original size by chrome plating and precision grinding.

BEP Surface Technologies

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