Fast Machining Centres Produce Fighter Aircraft Parts More Efficiently

Compared with using older production equipment, the high-speed cutting capabilities of modern machine tools can increase productivity considerably. A good example is the latest Ecospeed F 5-axis machining centre from DS Technology (UK). Since the first one was installed at BAE Systems Samlesbury, it has been working around the clock manufacturing components for the Eurofighter Typhoon much more quickly and economically than other machines on site.

Compared with DS Technology's 'ACM' machining centres originally purchased by BAE Systems to fulfil this and other work, the Ecospeed F is twice as productive, according to Nigel Tuley, Facilities Engineer at Samlesbury.

Furthermore, the fixed-column machine is 25 per cent faster than the previous generation of Ecospeed moving-column machines, three of which were installed at Samlesbury between 2003 and 2005. These machines form the basis of a flexible manufacturing system (FMS) that includes two load stations and a rail-guided vehicle for the transfer of six pallets to the three machining centres.

Two of the FMS machines are devoted to producing aluminium front fuselage sections (bulkheads, cockpit and instrument panels, etc) for the Eurofighter Typhoon, while the other machine produces aluminium details for the rear fuselage of the F-35 Lightning II.

By the middle of 2006, BAE Systems had won additional Eurofighter Typhoon work, namely the production of the centre fuselage frames. It became clear that the increased workload combined with the projected two-thirds increase in Eurofighter Typhoon build rate to 60 aircraft per year within 12 months would require additional production capacity at Samlesbury, even with the ACM machines deployed on this work as well.

So an order was placed for the latest generation Ecospeed F, which took over the finishing operations on the three types of centre fuselage frame, while two ACM machines were retained for rough-machining the castings.

Whereas roughing of the frames removes about half of the material by weight, finishing of the 2 m x 1.5 m components removes only 2 to 3 mm of material in cycles that are approximately eight hours per side, giving an indication of their complexity. Large apertures for the air intake and wing attachment lugs are finish milled, but the majority of the work is pocketing to remove weight. There is a lot of thin wall machining at 40:1 depth-to-thickness ratio and some at 60:1.

Mr Tuley commented, "Not only is the Ecospeed F more productive, but accuracy and surface finish are better as well. This is partly due to the high dynamic stiffness of the machine, and partly due to the uprated control system with enhanced look-ahead capability.

"The former allows faster axis acceleration / deceleration and cutting feed rate, which at 1g and 50 m/min respectively are high for a machine of this size.

"The axes therefore respond more quickly to commands from the CNC, so the cutter is less likely to deviate from the programmed path when the contour changes direction.

"In addition, the tool reaches the designated feed rate more quickly, so it is cutting at its optimum parameters for longer, which also has the effect of improving accuracy and tool life."

He said that the improvement is particularly noticeable on the edges of the frames, where after both sides have been machined, the mismatch along the centre where the milled paths meet is now almost indiscernible.

The success achieved with the first of this new generation of Ecospeed led to two more, virtually identical machines being installed, one of which was delivered in December 2008 and the other in September 2009.

The first additional machine has joined the existing model in the centre fuselage machining cell and replaced the two ACM machines that were being used for roughing operations.

In future, both Ecospeed Fs will split the roughing and finishing duties between them, doing the work that currently requires three machines. Even so, the two-machine cell will have spare capacity while Eurofighter Typhoon build volumes increase, as the machines will be able to supply 72 aircraft annually. Meanwhile, from next year the cell will assist the FMS with production of front fuselage components as well.

The second additional Ecospeed F will extend the use of the new machining centre technology to aluminium component production for the F-35 Lightning II, helping the FMS to cope with anticipated rate increase on this contract as well.

In the case of all three Ecospeed Fs at Samlesbury, the installations were supplied by DS Technology (UK) as turnkey projects that involved the company taking responsibility for the extensive foundations.

One of the features that gives the Ecospeed F its high performance capability is DS Technology's kinematically-driven, 2-axis Sprint Z3 spindle head rated at 80 kW (continuous) / 30,000 rpm. The spindle traverses through ± 40 degrees in the vertical rotary A-axis as well as in the horizontal rotary B-axis, both of which can be interpolated with the three linear X, Y and Z axes for full 5-axis machining. Short cutters, solid carbide in the main, are able to reach most areas on the components, contributing further to vibration-free, high accuracy machining.

The 125-tool magazine holds sufficient cutters to complete the machining tasks on both sides of all the centre fuselage components for the Eurofighter Typhoon. An HSK63 taper is employed with an 80 mm flange to provide added rigidity. Machining is carried out with the pallet in the vertical position to ensure efficient swarf removal.

On behalf of:

DS Technology (UK) Ltd, 43/45 Phoenix Park,

Avenue Close, Nechells, Birmingham B7 4NU.

Tel: 0121 359 3637. Fax: 0121 359 1868.

Contact: Jon McDonald, Managing Director.


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