Extraction systems deal with oil mists and smoke

When Renishaw moved into 100,000 sq ft premises in Stonehouse, Gloucestershire, in January 2006, the company realised immediate benefits from a state-of-the-art extraction system from Kitagawa Europe – a specialist provider of tailored custom workholding and manufacturing systems. Renishaw is using Kitagawa's ODF2000HPS and ODF1000S systems that are claimed to outperform industry-standard centrifugal and ionised element units to achieve at least 99.97 per cent oil separation.

In addition to the £5million purchase cost of the factory, Renishaw invested a further £2.5million to transform it into one of the UK's most efficient precision engineering operations. The 70,000 sq ft machine hall in the new facility for the company's machining and piece part manufacturing operation houses an impressive line-up of equipment, including high-performance Citizen M32 sliding head and Mori Seiki mill turn lathes, and Mazak vertical machining centres.

Renishaw manufactures its precision parts in one process at high speeds to give a very fine surface finish. As the neat oil used as lubrication for cutting and cooling heats up, it gives off smoke – causing a health and safety hazard, both from reduced visibility and potential respiratory problems.

Smoke stops work

David Pilborough, senior development engineer, explains: "When we first installed the Citizens we found we could employ more aggressive machining strategies. The new-generation machines allow much faster processes, but also generate lots of smoke. The only solution when the atmosphere gets that bad is to switch off the machines – and that is obviously detrimental to productivity."

Renishaw approached this problem in the way it has always done when purchasing equipment. Appropriate filtration systems were investigated thoroughly in terms of operation, cost and servicing. Various technologies were considered: 'box' type, centrifugal (Renishaw already had some on other machines – but they had always been problematic) and electrostatic.

Centrifugal units that were being used for mist control purposes caused vibration that was transmitted through the mountings, resulting in a poor surface finish on components. Smoke was escaping from every crevice of the machines. This problem was the main driver behind the purchase of filtration equipment from Kitagawa.

Free trials

Pilborough says: "We accepted that we would have to adopt a filtration solution throughout the machine hall, especially in view of current HSE requirements. We also have our own internal standards to provide employees with a pleasant atmosphere to work in, so it was essential that we tackled this issue in the best way and as soon as possible."

Renishaw took advantage of free trial offers, talked to companies involved in similar manufacturing processes and asked searching questions of suppliers – carefully reviewing all available data.

Even so, with machinery standing idle or operating at reduced performance, there had to be a limit on the amount of time that could be spent on trials. While there were less expensive options available, technical data was a much more important consideration than the price. Nothing would be gained long-term from installing filtration equipment that did not do the job properly or required constant maintenance.

Available in both oil and dust filtration versions featuring an advanced design that is said to provide a far greater filter area than competitive products, Kitagawa's systems achieve at least 99.97 per cent oil separation. They also eliminate sub-viral sized particles and carcinogenic contaminants down to 0.1 microns diameter.

Risk management

Renishaw had previous experience in using Kitagawa's system since testing the ODF2000HPS for a 10-week period commencing September 2002. The first installation was a single unit servicing two Citizen M32 machines, but the company now has one ODF-1000S on each because of aesthetics and risk management issues.

Pilborough states: "We monitored the quality of the air output from the units – filtered down to micrograms – and measured the particle contaminants. We found the units extremely effective, having only this year changed the filters on the first Kitagawa units we installed back in 2002. The filters on other 'box' systems we have in the factory need to be changed with much greater frequency.

"By default we are specifying and using the Kitagawa systems with our Citizen M32 machines. Without question, they have proved to be the best solution where neat oil/smoke is affecting the atmosphere."

Filtration units from Kitagawa also solved the problem caused by Renishaw's six Mori Seiki lathes. These use water-soluble oil that generates a mist that is emitted when a ceiling shutter is opened to position the gantry robots into the machines. There are three ODF-2000 units on the line, each shared between two lathes.

All the units are linked to beacons via an electronic pressure sensor to indicate when they fail to do their job – but, as yet, they have remained at 'green'.

Pilborough adds: "For the most part, the efficiency of the filter systems depends on the quality of the installation. The fitters must understand how they work to ensure that the ducting, flanges, positioning, etc are correct and possible leakage points identified. It is worth paying that bit extra for peace of mind and the confidence that we can 'fit and forget'.

"The equipment from Kitagawa is very reliable – it gives us no problems whatsoever. To meet best practice as set out by the HSE, we are considering fitting the filtration units to all of our other machines - even those not causing any mist or smoke – because they vastly improve the air quality for our employees working in the factory."