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The Airbus plant at Broughton, Flintshire has eliminated coolant fouling and disposal problems and improved productivity since installing Alfapure Z3 coolant treatment systems from Alfa Laval.

The Broughton site is responsible for assembling wings for the whole range of Airbus aircraft.

Crucial components in the construction of each wing are the spars, which comprise the frame of the wing and the stringers that provide strength and flexibility.

These stringers vary in length from 15 to 21m and are machined from solid aluminium billets, 200mm wide and up to one tonne in weight, on a purpose-built Dorries Scharmann CNC machine.

In the process, 80 per cent of the aluminium is removed so that only the core material, offering the best strength and flexibility, is used.

Accuracy is crucial to the operation and, typically, component tolerances are accurate to 0 to150microns on the horizontal surface and +-3mm on a 21m length of material.

Machining a 15m billet of 20/26 aluminium requires approximately 4.5 hours of machine time.

A coolant cascade is used continuously over the workpiece and tooling to ensure tool life and cutting accuracy, and to maintain the operation at the correct temperature.

Castrol Alusol A is a soluble cutting fluid specifically formulated for machining aerospace aluminium alloys without the staining problems that are encountered with conventional soluble cutting fluids.

Airbus engineers have devised a special attachment that ensures that the bulk of the aluminium is removed in sections.

This reduces the volume of swarf produced and makes the job of scrap disposal much simpler.

However, during the cutting operation tramp hydraulic oils can become entrained in the coolant along with swarf and other metal fines.

Coolant and swarf are fed into a Mayfran coolant and swarf management system where the two elements are separated in a series of settling tanks.

Although this efficiently decontaminates the swarf and the solid scrap ready for disposal, it does not treat the coolant itself.

In the past, this led to severe problems with contaminated coolant.

Tramp oils entrained in fluid can lead to bacterial growth and represent a potential health hazard.

In addition, tramp oil tended to leave a film on the cylinders inside the CNC machine, which allowed foreign objects to adhere to them.

Dealing with these problems was both time and labour intensive.

The Airbus stringent health and safety rules meant that the whole line had to be shut down to enable the interior to be manually cleaned.

Personnel involved in this operation had to wear protective clothing and breathing apparatus.

Since the stringer production line is designed to operate continuously, except for scheduled maintenance periods, any unscheduled stoppage represented a significant loss of production.

To solve the problem, engineers at Airbus had to replace the coolant at frequent intervals.

This was expensive for two reasons.

First, the cost of the coolant and second because of the need to employ specialist contractors to handle the waste whose disposal is governed by strict environmental regulations.

Consequently, they investigated the possibility of recovering coolant to extend its life and eliminate disposal problems.

They researched a number of coolant recovery options before settling on the Alfapure Z3 system from Alfa Laval.

Based around a high speed centrifugal separator, the Alfapure Z3 cleaning module is a compact, mobile unit that occupies less than 3m2 of floor space.

Operation is via a PLC-based control system that uses a touch screen to provide a clear overview and touch control of all functions and efficient removal of tramp oil, grease and particles from coolants and other wash liquids.

Automatic in operation, the system requires no supervision.

Waste volumes are low and the self-cleaning separator is easy to service and maintain.

Continuous cleaning with an Alfapure Z3 prolongs the life of the service fluids.

In fact, the life of wash liquids can be extended by up to six times and, with topping up, coolants can last as long as 10 years.

Filter replacement and disposal costs are also reduced or eliminated.

It was this combination of features that attracted Alfapure Z3 to Airbus.

The machine installed in the stringer manufacturing shop continuously cleans 3,000 litres of Alusol A coolant per hour and returns it to the production line.

Since the machine was installed, according to Airbus engineers, they have eliminated the problem of contaminated coolant completely.

There is no more bacterial growth and, most important of all, no more extended and unscheduled breaks for clean-up operations.

The Alfapure Z3 has been operating for two years now and, in that time, the only additional coolant that Airbus has had to purchase has been needed to top up fluid lost to atmosphere or on workpieces or scrap.

A second Alfapure Z3 module is also in operation in the wing spar production plant, where it is used to clean and recycle a water-based coolant, Cimstar 560, which cools a large Ingersoll machining centre.

Alfa Laval's operations are based on leading global positions in the three key technologies of heat transfer, separation and fluid handling. Continuous product development is essential to strengthen competitiveness. About 2.7 per cent of total sales are invested annually in research and development, resulting in 25–30 new product launches a year.

Alfa Laval's products are sold in approximately 100 countries, 50 of which have their own sales organisations. The company has 20 large production units (12 in Europe, six in Asia and two in the US) and 70 service centres.

The customer's peace of mind depends on having the right service setup. For Alfa Laval, service is a total concept that covers everything from supplying the smallest spare part to being a lifetime performance partner. Alfa Laval has a global network with more than 200 skilled service specialists, a broad range of competitive service solutions, unique expertise based on more than 120 years in business and service centres in hundreds of locations in more than 50 countries.

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