Multi-stage filters maintain productivity

Traditional oil mist filtration equipment can sometimes struggle to cope with the demands of high productivity machining operations, but Absolent filter units are designed to satisfy.

The increased capabilities of latest generation machines and cutting tools, combined with customer demands for ever shorter lead times, continually push companies to increase speeds and feed rates in order to maximise their productivity.

But solving one set of problems, can sometimes lead to another.

The adoption of more aggressive machining regimes will often result in increased vaporisation of cutting fluids - producing a marked deterioration in employees' operating conditions and in turn, raising serious health and safety concerns.

Yet, as Wiltshire based David Hart Engineering found out, traditional oil mist filtration equipment can sometimes struggle to cope with the demands of high productivity machining operations.

Established more than 25 years ago in Downton, near Salisbury, David Hart Engineering specialises in producing high precision components for the telecommunications, automotive and aerospace sectors.

It is currently in the throes of a multi-million pound investment programme, which in some ways will see it go back to its roots - as its production facilities are geared up to attract a higher throughput of aerospace work.

When the company moved to a brand new manufacturing facility 18 months ago, the first thought was to equip each of its each new machine tools with a traditional centrifugal oil mist control unit.

But on closer investigation, it was found that the filters in mind could barely meet current health and safety requirements, let alone future needs.

"Because we operate round the clock and promote our ability to produce highly toleranced components on short lead times, we are always running our machines and cutting tools near their limit of performance," says Hart's Production Manager, Adrian Roberts.

"It is not uncommon for us to receive CAD models electronically from customers and, depending on their complexity, to turn them round as finished machined parts in 12 hours, if necessary.

"The downside to this is that the high speeds and feeds we use increase coolant vaporisation and the danger of releasing oil fumes and contaminants into the workshop atmosphere." Currently, Health and Safety regulations call for a maximum of 5 mg of contaminants per cubic metre of air, measured at ground level.

However, legislation in this area is moving steadily towards more stringent emission level standards.

"We employed traditional oil filtration equipment at our previous premises," reports Roberts.

"We knew it was capable of achieving a figure of around 2 mg/m3.

Even so, we were conscious that its performance was liable to deteriorate significantly over a period of time.

With the prospect of moving into a purpose-built new facility, we were doubly keen to maintain a clean and safe working atmosphere - and avoid the risk of any tell-tale brown stains building up on the walls or ceilings!" "Outdoor air will typically have a particulate value of around 1 mg/m3.

Our target was to reduce airborne contaminant levels in the factory to as close to zero as possible." After evaluating a number of options, Mr Roberts and his colleagues found that the performance of Absolent filter from Kitagawa Europe stood head and shoulders above the competition.

Units are available in both oil and dust filtration versions and feature an advanced design that provides a far greater filter area than competitive products - enabling them to achieve at least 99.97 per cent oil separation - to consistently outperform industry-standard centrifugal and ionised element units.

Systems will also eliminate sub-viral sized particles, as well as carcinogenic contaminants down to 0.1 microns diameter.

As a result of their study, eight off Absolent two and three stage filter units were specified for use with the 20 high-capability machine tools installed at the company's new manufacturing facility.

The performance of the filter units has been monitored regularly since their installation around 12 months ago, and according to Roberts: "readings from their exhaust consistently register virtually zero, showing that the re-circulated air is actually cleaner than so-called fresh air." "The Absolent units are also very quiet in operation and, unlike many other units, require only minimal routine maintenance, such as washing of the pre-filters, to keep them at peak efficiency." A high proportion of Hart's work involves machining components from aluminium, stainless steel or titanium.

However, a further benefit of the Absolent units comes to the fore when the company is called to produce parts from engineering plastics.

"Previously any machining operations on these materials would be associated with the distinctive smell of formaldehyde," says Roberts.

"But, now this has been completely eliminated, thanks to our Absolent units." Such has been the success of the filters that a further series will be employed when the company installs 20 more multi-axis machines in a second new manufacturing hall currently being built on site.

Due to be operational within the next three months, this latest phase of Hart's investment programme will incorporate a number of three, four and five axis milling machines, along with an eight-axis turning centre.

"We believe that choosing the best production machines and equipment gives us a significant competitive advantage; enabling us to provide a top quality service to existing and new customers alike," Roberts adds.

"In parallel, our continued expansion means we are always looking to recruit high quality, skilled production engineers." "The creation of a clean, modern and safe working environment can therefore only be an advantage when it comes to attracting and retaining the best candidates.".

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