The success of a seven-machine ECOSPEED F flexible manufacturing system (FMS) at Korea Aerospace Industries (KAI) has led to an order for two additional ECOSPEED F machining centres were integrated into the system in June 2016 to enable KAI keep pace with its growing Airbus order book.
Supplied progressively the 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’.
Each individual wing rib starts life as a billet, weighing up to 4,123 kg with dimensions of up to 5,700 mm in length, 1,700 mm in width and up to 200 mm thick. Finish machined components weigh as little as 112.7 kg. It is not unusual to remove 90% of the original stock material. Machining operations include surfacing, pocketing and drilling. The ribs are made form Aluminium and Aluminium/Lithium alloys.
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 F order with Starrag.
A shortlist of four suppliers was tasked with machining an appropriate test part. Only two companies could produce the part complete, and the ECOSPEED F far outweighed the competitor in terms of cycle time and finished quality. Indeed, the ECOSPEED F 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 nonstop at 30,000 revs/min in S1 mode – coupled with the machine’s high dynamics in acceleration of 1 g in all five axes and jerk up to 200 m/s³. Indeed, an ECOSPEED F machining centres can transform a four-tonne aluminium billet into a 120 kgs complex structural part in less than 20 hours when the machine is running at a maximum cutting volume of up to 10,000 cm3/min.
The system’s ECOSPEEDs are linked by a rail conveyor system with 55 loading, unloading and storage stations for the machines’ 60 pallets, each one measuring 2,000 mm by 6,000 mm. The conveyor system was installed by MSB, a Starrag partner, and all process criteria, tooling, fixtures, programming routines and tests were completed by Starrag engineers.
Each of the ECOSPEED F machining centres features a Sprint Z3 parallel kinematic machining head, which boosts the machine’s ability for highlydynamic, simultaneous five-axis/five- sided milling. The head uses three parallel linear axes drives mounted radially equispaced 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.
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 +/- 45 deg at a maximum of 80 deg/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 -135 deg to 135 deg.
Each ECOSPEED F also features Siemens Sinumerik 840D CNC control, a 129-position Regal tool magazine, vacuum workpiece clamping and video monitoring of the work area.