Reaching new heights
Flexible manufacturing system represents a productivity leap for aircraft manufacturers
The pallet system integrated by the Starrag Group includes a total of 16 pallets measuring 2,000 mm × 4,000 mm.
Final assembly hall at the Pilatus Aircraft factory in Stans, Central Switzerland: You experience the wonder of flying much more here than when you’re sitting in an “ordinary” passenger aeroplane. Here there are the newest models of the PC-12, a single-engine multi-purpose aircraft which has sold more than 1,500 units, some examples of the highly-modern PC-21 training plane and three prototypes of the twin-engine PC-24 Business Jet. These were certified in 2017 and 80 orders have already been received for them: it's hard not to grab the joystick yourself and take off.
It’s no wonder that Pilatus has conquered different niche markets with these relatively small aircraft. Because they impress with their high quality, individual equipment and performance characteristics, as well as the multiple award-winning worldwide customer service. With around a 65 % share of sales, Asia is the largest sales market for the Swiss company, followed by America with 23 % and Europe with 8 %.
Pilatus’ FMS in Stans contains two identical horizontal machining centres of the ECOSPEED F type, which were specifically developed for the high-speed machining of mid-sized large structural components from aluminium.
For years, turnover and orders have been increasing continually and now the PC-24, known as the Super Versatile Jet, has reached market maturity, production capacity requirements will reach a new high. Since neither available space nor staff numbers can be increased indefinitely, those in charge chose to breathe new life into the machining of large parts and therefore achieve additional capacity.
After all the new business jet, like all other Pilatus aircraft, consists of numerous aluminium structural components from nose to tail fin and wing tips. “Machining them is one of our core competencies,” explains Walter Duss, Head of Mechanical Production. “As they have a wall thickness of only 1.2 millimetres at times, they are extremely delicate. This is not the case for all aircraft manufacturers. Machining efficiency is therefore usually well over 90 %.”
To increase productivity in this knowledgeintensive core segment, a flexible manufacturing system had to be installed for components between 750 mm and 4,000 mm in size, which enabled a largely automated production process. Other important points in the specification were the ability to retool during machining time using a work buffer in the pallet magazine, as well as a generally reduced retooling requirement in order to economically handle Pilatus’ range of over 200 parts in this size category.
Flexible manufacturing system creates additional capacity
Beat Müller, Project Leader for Equipment Procurement and responsible for the investment in the flexible manufacturing system, included all of the wellknown aerospace industry suppliers in his invitation to tender. They had to undergo an intensive benchmarking process, at the centre of which were numerous test processes. In the end, the tender was awarded to Starrag Group, who are to supply a flexible manufacturing system with two identically-equipped ECOSPEED F 2040 machining centres.
Pilatus machines parts of between 750 mm and 4,000 mm in length using the new Starrag FMS. Walter Duss (left), Head of Mechanical Production, and Ahmad Rabah, a multi-skilled mechanic specialising in machining large parts, both from Pilatus, indicate that – having a minimum wall thickness of only 1.2 millimetres – the parts are extremely delicate.
“With the ECOSPEED F machines we achieve excellent quality and are much more productive than in the past.”
“What fundamentally shone for the Starrag Group was their comprehensive system knowledge and their many years of experience completing successful turn-key projects,” described Beat Müller. On the machine side, the performance of the ECOSPEED F machining centres was especially convincing, designed specifically for the machining of aluminium structural components and reaching a span volume of up to 160 l/min. Beat Müller described the Sprint Z3 parallel kinematic machining head as particularly innovative: “It especially impressed us when it came to pocket milling in the corners with different angles of attack.” Another decisive factor was the spindle with its maximum speed of 30,000 rpm and an output of 120 kW. It provides a diagnostic function – “a must-have criterion for us,” adds the project leader. “Because this enables us to optimally design the process, also in terms of maintenance and other running costs.”
The highly-automated production is supported by another product developed and supplied by the Starrag Group – a production control computer. This manages the machine duo’s collaboration with pallet and set-up stations. Staff always have a clear overview of the processes on the monitor.
The project leader also named the optimal chip fall of the ECOSPEED F as a deciding factor: “We estimate that nearly 700 tons of raw material is machined in the machine every year, of which more than 90 % is removed. This is a huge volume of chips that has to be removed from the machine and the production area. ”The vertical arrangement of the machine pallet guarantees that chips will fall directly into the central swarf conveyor. The conveyor moves the chips to a cross conveyor in the basement, which finally moves them to a silo with four briquette presses. After pressing, the briquettes are transported from the hall to a waiting container.
The pallet system integrated by the Starrag Group includes a total of 16 pallets measuring 2,000 mm × 4,000 mm.
The Starrag Group provides the project planning and engineering of the whole FMS, which includes a pallet handling system in addition to the machining centres. There are a total of 16 pallets in the system, with dimensions of 2,000×4,000 mm. Of these, one is located in each machine, and 14 are in storage locations. The system also contains two set-up stations with a tilting table to allow vertical loading. The highly-automated production is supported by another product developed and supplied by the Starrag Group – a production control computer. This manages the machine duo’s collaboration with pallet and set-up stations.
High process security enables unmanned night shift
Project leader Beat Müller: “Thanks to the high process safety of the Starrag Group FMS, we can now run the night shift with no staff.”
The Starrag FMS has been in operation since the autumn of 2016. Production manager Walter Duss is satisfied: “With a similar production area and the same amount of staff, we generate approximately one third more capacity. This makes us much more economi- cal – something that helps us meet strong international competition in an expensive manufacturing country like Switzerland.”
Project leader Beat Müller also recognises that a major goal has been achieved: “We used to have a shift model in which our machine operators worked continuously 300 days a year from 5 am to 1 am. It was followed by four hours’ unmanned operation. The system’s process-safe operation allows us to run the system unmanned from 10 pm until 5 am, and so free up our staff for other tasks.”
As a further benefit he mentions that tooling – which happens manually due to the large variety of parts – can take place while the machines are running. The pallets are loaded during the day shifts. In order not to lose any time in doing so, Pilatus has integrated a raw material storage location opposite the set-up point to provide the required blanks. The setup pallets are stored in the magazine. From there, the Starrag production control computer automatically sends them for machining on the machines and ensures that they are returned to the magazine afterwards. Beat Müller indicates that some twelve production orders run on the system at the same time. The pallets are thus placed in storage again between intermediary work steps. Beat Müller summarises: “The buffer effect of the pallet magazine definitely allows us to achieve higher utilisation.” Once machining is complete and there is capacity for unloading, the finished pallet travels to the set-up point, where it will be manually unloaded and reloaded.
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