Big structural parts machined faster

Horizontal 5-axis machining, high spindle power, long-term reliability, small floor space, and the flexibility to efficiently machine all their big structural parts on one machine led Aircraft Industries to choose a 5-axis horizontal HBZ AeroCell machining center.

The Czech aircraft manufacturer performs design, aluminum sheet and roll forming, steel forming, machining, welding, riveting, surface treatment, hardening, painting, measuring, assembly, testing, and overhaul under one roof. The company covers the whole process from raw material to the finished aircraft in building the L 410 twin turboprop commuter aircraft designed for severe flight conditions. German machine tool manufacturer Handtmann is an integral part of the L 410 production chain.

Tradition and progress
With approximately 1,000 employees, Aircraft Industries produces around 10 planes per year. The company was founded in 1936 when AVIA Letnany built a branch in Kunovice, Czech Republic, to service its planes, and since then, the company transformed from a repair center into the only producer of small civil transport aircraft in the Czech Republic and one of the largest employers of the region. The first aircraft was built on the company premises in 1957, and the first L 410 was test flown in 1969. More than 1,200 of the L 410 series have been made with production continuing uninterrupted. Now, more than 350 of them are operated in more than 50 countries around the world. The Aircraft Industries name has existed since 2005 when Czech owner PAMCO created it. LET remains as a brand but not as the company name. Having the majority of shares since 2008, the Russian Industrial Holding UGMK became the owner in 2013.

Aircraft manufacturing, production subcontracting
Aircraft Industries produces small civil transport aircraft and is a major supplier of structural aircraft components. The professional know-how, large production capacity, quality, and technology enable it to source parts for other aircraft manufacturers and suppliers such as GKN Aerospace Transparency Systems (leading-edge slots for the wings of Boeing 787 Dreamliner and engine air intakes for CASA CN-235 aircraft) in addition to machining parts for its own aircraft. Machinery modernization has increased production capacity for subcontracting, so the aircraft manufacturer can offer expertise to its partners.

An aircraft for severe conditions
The L 410 twin-engine turboprop aircraft – made for short-haul transport from remote and undeveloped areas to major cities – flies at a maximum height of 4,000m. The L 410 UVP-E20 standard version holds 19 passengers. It can also be used for cargo, air ambulance, sky diving, maritime surveillance, and photogrammetric scanning. The company’s target markets are closely linked to the aircraft’s capabilities: short, unpaved airfields with severe take-off and landing conditions such as rain-soaked grass, sand, snow, and slush. The aircraft can be reliably operated from -50°C to 50°C. Besides Russia, the company’s target markets are Southeast Asia, Africa, Latin America, and Europe. 

With more than 1,200 aircraft since start of production in 1969, the L 410 NG (new generation) was officially presented at ILA Berlin 2016 and MAKS 2015, advancing the current L 410 UVP-E20. Start of serial production of the NG is planned for 2018 for orders already placed. Major improvements include more space for luggage, higher maximum payload, higher maximum cruising speed, less fuel consumption, longer maximum range (from 1,520km to 2,630km), extended maximum endurance (from 5.1 hours to 10 hours), reduced propeller noise, and increased fuel capacity.

“With the newly designed wing structure made of large milled solid panels instead of riveted parts – which contains an integral fuel tank with more fuel capacity – we can offer to customers much more added value compared to the old aircraft design,” says Antonín Michalec from the subcontracting department. The current aircraft provides for 1,300kg fuel whereas the new wing design provides for a fuel capacity of 2,260kg. Major changes in the aircraft include the main structural wing parts – the main reasons for new machinery. This is where Handtmann comes into play.

The HBZ AeroCell 
With the new generation of L 410, milled aluminum parts will significantly increase, and much larger parts will be included in the wing structure such as the approx. 6,300mm x 1,000mm wing panel. To be prepared for this amount of milled parts, Aircraft Industries officials were looking for a machine able to manage the large variety of structural parts in the most productive and space-saving way. 

“We needed one machine for all big structural parts. The machine has to cover 20 parts varying in size and type from small ribs up to the large wing panel milled from one solid aluminum block,” says Oldrich Zich, an NC programmer who has been involved in the buying process from the beginning. “Flexibility and productivity have been the keywords in the buying process.” 

Zich, who has worked for Aircraft Industries for 35 years, adds: “The horizontal concept was a prerequisite from the beginning. Aerospace structural parts require maximum material removal when aiming for short cycle times and good surface quality together. Chip and coolant management as well as tool life are better with horizontal machining.” 

The Handtmann 5-axis horizontal machining center HBZ AeroCell 700/200’s 7,000mm x 2,000mm pallet and 7,800/2,050/700mm X/Y/Z-axis travels fit the parts and other requirements, such as high spindle parameters with 156kW maximum power, 30,000rpm spindle speed, and an integrated pallet changing system. Travel speed of 80m/min and accelerations up to 7m/s² represent the required dynamics. According to Zich, the long-lasting, stable, and reliable HBZ AeroCell construction was a main advantage against competitors’ machines.

Besides the machine facts, the personal relationship and trust are important for Aircraft Industries.

“With Handtmann, we felt like we had a strategic partner from the beginning,” Zich says. “We still have good cooperation almost two years after the machine’s installation and an exceptional level of trust.” He notes the quick help with technological questions, short reaction times, service, and spare part availability. 

More than 50% decrease in machining time
Early in 2015, Aircraft Industries started to machine all structural parts on the Handtmann HBZ AeroCell 700/200. The machine’s utilization will increase with start of L 410 NG serial production, but capacity will remain for subcontracted deliveries.

Aircraft Industries can already prove some decreases in machining times compared to various 5-axis vertical machining centers: 
• Bogie beams, 3,300mm x 200mm, 40 hours to 20 hours 
• Bottom wing panel, 6,300mm x 1,000mm, 100 hours to 30 hours 
• Upper wing panel, 3,300mm x 1,200mm, 80 hours to 25 hours
• Fuselage segment, 2,000mm, 13 hours to 9 hours

A machine operator’s point of view 
Jirí Urminský, who operated the HBZ AeroCell during test milling of parts, highlights the high speed of the machine. Even the speed of the chip conveyor is high, transporting large amounts of chips quickly outside of the work zone. To handle the huge number of chips, Aircraft Industries installed an extra-large briquetting plant. Despite the complex and advanced technology, the machine is “easy to operate,” Urminský says. He also notes the training which “was extensive and profound. If there’s still any problem, the remote control and quick support from the Handtmann service makes it easy to get the machine running again quickly.”

The future
Commercial Director Robert Erhart says, “We will continue investing in new technologies to keep on track with other aircraft manufacturers and suppliers, to be able to always offer the best quality not only as final aircraft producer but also as sub-deliverer.” 

Keeping production of milled parts completely in-house will lead Aircraft Industries to invest in more machinery. Aircraft Industries is considering the Handtmann PBZ HD profile machining center and HBZ Trunnion horizontal machining center with NC-rotary swivel table for complete machining of complex small parts in one clamping.

“With the Handtmann HBZ AeroCell we got ourselves prepared for future growth. Especially with our L 410 New Generation, production will increase and so has our production capacity. With Handtmann, we found a reliable partner to do so,” Erhart adds.

Handtmann A-Punkt Automation GmbH

Aircraft Industries a.s.