Productivity and safety benefits
November 1st 2003

John Green, business manager, oil mists and filters looks at the influencing factors behind Nedermans new product range Anyone who has ever worked on a shop floor where multi spindle or single spindle automatic lathes are in use will remember one thing in particular. Slippery floors. No matter how good the general standard of housekeeping in these places, the necessity of using neat cutting oils to aid machining efficiency and the heat generated by the machining process ensure an atmosphere and every uncovered surface are lubricant rich. Although many companies have been able to replace neat oils with soluble and synthetic cutting lubricants, the presence of oil mist in machine shop atmospheres remains a problem. There remain plenty of factories where the combination of ice-rink-like walkways and contaminated air constitutes a two-pronged attack on the health and safety of personnel. Machining processes, which can generate a lot of heat, give rise to two types of oil or coolant based emission. The higher proportion is mist produced by the impact of pressurised coolant on surfaces within the machine. In addition there is localised evaporation of coolant, both in the vicinity of the cutting zone and from passive heating as the machine attains its ideal operating temperature. In addition processes where very high temperatures are attained will produce gaseous fumes caused by breakdown of the coolant or, in extremis, localised combustion. Injection moulding processes may also lead to flash evaporation of volatile constituents of the plastic. Albeit COSSH regulations have done a lot to help, managers are faced with the conundrum of identifying an effective filtration solution whose installation and running costs do not compromise competitiveness. It can be argued that some of the cost might be recouped through a reduction in the expenses associated with sick leave, workplace accidents slips, trips and falls account for around 80 per cent of workplace injuries cleaning and equipment breakdown arising from oil getting to where it isnt wanted. Moreover, heat is retained in the recirculated air so energy bills may reduce. However although the workforce will probably be happier when working in a cleaner environment it is fanciful to suggest that productivity will rise appreciably. In those manufacturing sectors where filtration makes the most difference productivity is determined by the capabilities of the equipment rather than the will of man. Many of the companies for whom the need is most acute are engaged in highly cost sensitive high volume manufacturing where fractions of a penny determine profit or loss on a contract. When formulating its range of oil mist filtration systems, launched early in 2003, Nederman took all of these factors into account. As with all of the companys workspace safety equipment the design aims centred on development of systems that would provide a highly cost effective solution. To that end the NOM filter range offers filtration efficiency up to almost 100 per cent and is designed specifically to recover accumulated filtrate to a collection tank or return it to the machine. The filtration options available to machine shops include cartridge types mechanical filters, rotating separators and electrostatic filters. Whilst the latter two formats are highly effective, for the NOM range Nederman opted for a two stage concept combining a washable mechanical pre-filter with the option of a HEPA cartridge filter. Air is drawn into the NOM filter and circulated radially by a turbulator fan; the pre-filter is around 90 per cent efficient and removes larger droplets and particles from the air stream. The semi-cleaned air is then drawn through the HEPA filter which removes most of the remaining droplet and particular contaminants. Overall efficiency of the combined filter system is around 99.97 per cent for oil mist; Nederman stresses that NOM is not a gas filtration system so processes giving rise to significant quantities of gaseous emissions need supplementary filtration. NOM filters are sized to cover a range of applications from stand-alone installations to centralised systems for up to six machine tools. This flexibility, combined with ease of installation, was instrumental in NOM gaining a major order from Bosch to equip a large automotive components factory in Poland with up to 50 NOM units. Key advantages of the NOM design are the self cleaning nature of the pre-filter, self-draining capabilities. They endow the systems with suitability for long periods of operation without need for maintenance. Moreover the washable pre-filter prolongs the service life of this consumable whilst low operating noise levels of less than 70dB help it to integrate into the work environment unobtrusively. Filter life is bound to be an issue with any system of this type and obviously depends on the duty cycle and the type of oil mist encountered. The ideal application is a lightly flowing oil emulsion that rapidly drops away from the first pre-filter into the drain. By contrast a higher viscosity filtrate may compromise the self cleaning properties of the pre filter. One option, highly useful where inconsistent conditions may be encountered, is a simple pressure gauge kit, that measures the pressure drop through the filters, providing timely warning of saturation and the need to wash the pre-filter.

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