The use of a Scharmann Ecospeed horizontal machining centre has allowed specialist aerospace supplier Magellan Aerospace (UK) Ltd to slash machining times of Airbus A350 aluminium wing ribs at its Llay site near Wrexham and fulfil the commitments it made to its customer — achieving a saving in cycle time of more than 75% for a particular part.

Operations manager Adrian Young says that Magellan first investigated the potential of the Ecospeed when it began comparing the economics — and effectiveness — of machined aluminium wing ribs against composite wing ribs. “Our ‘new’ design of machined wing rib incorporates lots of pockets, so we needed a machine that would allow us to produce these most effectively.

"We knew about the Ecospeed’s ability to remove aluminium at a rate of 8,000cm3/min, but we wanted to compare it with other potential solutions for machining these high-value components, which can start life as four-tonne billets but weigh just 140kg when machined.

“It was subsequently clear that the high-speed Ecospeed — with feed rates up to 50m/min, an advanced CNC system and the Sprint Z3 machining head — was the machine for the job. When machining, the speed of change of direction and ramp-up seemed to be the Achilles heel of the other machines we looked at. Moreover, the superior jerk functionality available via the Ecospeed’s Siemens 840D CNC meant there was no significant loss of speed and accuracy when pocketing.”

Novel head actuation

Notable features of the Ecospeed F2060 — supplied by Birmingham-based Starrag UK Ltd (www.starrag.com) — include its fixed column and Sprint Z3 machining head. This head uses three equally spaced parallel linear axes mounted radially in the headstock. The spindle platform is connected to each drive via rigid levers with a pivot at one end and a ball joint at the other.

Synchronised motion of the three Z axes allows the spindle to follow any path within a circular cone of ±40deg at a maximum speed of 80deg/sec. Equal and simultaneous motion of all three axes results in a straight-line movement of the spindle in Z; if the three axes move differentially, the spindle platform will be tilted in the A/B planes.

The Ecospeed also features a 120kW 30,000rev/min spindle, a work envelope of 6,300 x 2,500 x 670mm, and a twin-pallet automatic changer (with a change time of 210sec) for pallets of 2,000 x 6,000mm that accommodate payloads (component and work-holding) of 5,000kg and measuring up to 2,000 x 6,000 x 370mm.

A rack-type automatic tool-changer/magazine houses up to 129 tools and offers a chip-to-chip time of 9sec. Other features include minimum-quantity lubrication and mist extraction, in-process component probing, tool breakage control and a vacuum supply for component clamping.

When in 2008/09 Magellan tendered for the A350 wing rib package (for ribs up to 6m long), Mr Young already had the Ecospeed in mind.

“Part cost is at the heart of every contract we tender for, and contracts are usually based on fixed prices — except for material costs — over a number of years, so it is essential that we calculate the cost of each capital investment against realistic cycle times based on often very lengthy forward order forecasts. It’s a complicated ‘balancing’ act, and it’s one we have to get right every time if we’re to stay in business.

“That said, the Ecospeed machine has been working ‘flat out’ — and reliably —- for the past 12 months. It has also attracted new work, including wing ribs for A380 and A320 aircraft, as well as other Airbus parts.

"Indeed, the machine has been so successful that we recently placed an order for a second, similarly equipped Ecospeed F 2060 to meet this demand, as well as to satisfy the pre-planned increase in A350 orders. Furthermore, the second machine will allow us to bring back in-house certain work that is currently out-sourced.”

Continual improvement

Mr Young says Magellan’s on-going manufacturing success is based on a policy of continual improvement in every aspect of every operation. “This is why we’re continually working with our machine suppliers like Starrag UK, with our aerospace clients’ designers and with our tooling suppliers. For example, on the A350 wing ribs, we are currently investigating new tooling that takes deeper and closer-to-the-wall cuts, to leave just a single-pass finishing routine and allow us to cut cycle times further without jeopardising product quality.

“This follows the successful application of Sumitomo’s SumiDrill WDX drills, which have transformed drilling tasks on a range of spars. These drills are being run 60% faster than the previous tooling; in one instance, they have produced 200 holes, compared to just 10 before the previous drill either failed or required an insert change.”

Clever programming also plays a key role in fully utilising the Ecospeed’s capabilities in terms of wing rib machining, and Magellan ensures that it has access to the best programming skills available to improve machining routines and cycle times — courtesy of its in-house programmers, Starrag UK’s technical team or expert ‘freelancers’.

Magellan also has sites in Blackpool (for hard-metal component work), in Bournemouth (aluminium parts), in Chalfont, Bucks (aluminium parts), and at Greyabbey in Northern Ireland (wing ribs up to 4m). Magellan Aerospace (UK) Ltd is owned by Magellan Corporation — a global aerospace company with operations throughout North America, Europe and India.