The success of a seven-machine Scharmann Ecospeed flexible manufacturing system (FMS) at Korea Aerospace Industries (KAI) has led to an order for two additional Ecospeed machining centres to be integrated into the system by June 2016 to enable KAI keep pace with its growing Airbus order book.

Supplied progressively by Scharmann, a member of the Swiss Starrag Group, the original machine/FMS order was placed in 2009; the sixth and seventh machines for the system were installed and started cutting metal at the beginning of 2015 at KAI's site in Sacheon, South Korea.

The FMS has been used by KAI as part of its successful ramp up of the manufacture of complex structural components for the Airbus A350 XWB international joint development programme, for which KAI is a 'Top 20 Supplier'.

Individual wing ribs start life as a billet weighing 4,123 kgs and measuring up to 5,700 mm by 1,700 mm by 200 mm thick. Finished machined ribs weigh just 112 kgs after a thorough machining sequence involving, for example, rough pocketing, rough and finish machining of the datum face, semi- and finish-machining of the rib including pockets, as well as hole drilling and the machining of each end. The ribs are made of aluminium alloy/aluminium lithium alloy.

KAI initially made production studies on existing 20-year-old gantry-type machines before evaluating all available machining options and alternatives with a number of machine builders/suppliers, before placing the Ecospeed order with Scharmann.

A shortlist of four suppliers was tasked with machining an appropriate test part. Only two companies could produce the part complete, and the Scharmann Ecospeed far outweighed the competitor in terms of cycle time and finished quality. Indeed, the Ecospeed proved between 30 and 50 per cent faster!

The Ecospeed's main spindle motor performance plays a key role in such machining performances – rated at 120 kW it can run non-stop at 30,000 revs/min in S1 mode – coupled with the machine's high dynamics in acceleration of 1g in all five axes and jerk up to 200 m/s³. Indeed, an Ecospeed F machining centre can transform a four-tonne aluminium billet into a 120 kgs complex 120 kgs complex structural part in less than 20 hours when the machine is running at a maximum cutting volume of up to 8,000 cm3/min.

The system's Ecospeeds are linked by a rail guided vehicle (RGV) with four loading/unloading stations and 55 storage stations for the machines' 60 pallets, each one measuring 2,000 mm by 6,000 mm. The RGV system was installed by MSB, a Starrag partner, and all process criteria, tooling, fixtures, programming routines and tests were completed by Scharmann engineers.

Each of the Ecospeed F machining centres features a Sprint Z3 parallel kinematic machining head, which boosts the machine's ability for highly-dynamic, simultaneous five-axis/five-sided milling. The head uses three parallel linear axes drives mounted radially equi-spaced in the headstock. The spindle platform is connected to each drive via rigid levers with pivots at each end and a ball joint at the other.

When all three axes move simultaneously, the spindle is moved in a straight line in Z; synchronised motion of the three Z axes allows the spindle to follow any path within a spherical cone of +/- 40deg at a maximum of 80deg/sec. If the three axes move differentially, the spindle platform will be tilted in the A/B kinematic.

Each machine has an integral C axis to allow the use of automatic interchangeable angular milling heads which operate at every spatial angle between -130deg to 130deg.

Each Ecospeed also features Siemens Sinumerik 840D CNC system, a 125-position Regal tool magazine, vacuum workpiece clamping and video monitoring of the work area.