Cessna Aircraft Company will soon celebrate its 90th anniversary, and is busier than ever. In terms of unit sales, Cessna is the world’s largest manufacturer of general aviation airplanes. In 2005, the company delivered 1,157 jet, turbo-prop, and piston aircraft for business and personal use, and over its history has supplied more than 187,000 airplanes to nearly every country in the world. Production efficiency is key to Cessna’s global competitiveness, and their in-house parts fabrication system is a prime example. Since the 1970s, the company has manufactured virtually all of its sheet metal components using Flexform™ high pressure fluid cell technology from Quintus (then known asASEA/ABB).
The Flexform concept
In Flexforming, sheet metal blanks are formed over a single, rigid, shape-defining tool half by a flexible rubber diaphragm under uniform hydraulic pressure. Tools and blanks are placed, without fixing, into trays on each end of the press, which shuttle in and out of the central frame containing the pressurized diaphragm. Cessna’s large QCF press features 13.1 ft x 4.4 ft (4 x 1.35 m) forming trays and a maximum operating pr essure of 14,500 psi (100 MPa, a pressure generating a force equivalent of 72,000 tons). This is used primarily to produce large panels and components from aluminum blanks ranging in temper from T4 to O. The more complex the shape, the softer is the temper.
“We can control the pressure more accurately on small parts in this press and eliminate even more touch labor. The press is easy to operate, is ergonomically friendly, requires little time to train operators, and needs little maintenance.” Mike Irwin, Manufacturing Manager, Cessna
High quality parts the first time
Cessna has become proficient in high pressure forming at their Wichita, Kansas facility. Multiple parts can be processed in a single three minute cycle with little or no secondary work. Mike Irwin, Cessna’s Manufacturing Manager, says “We are very confident with the quality of the parts out of the press. The metal spreads out evenly, and there’s very little ‘tweaking’ needed”. This one-shot accuracy is a result not only of Cessna’s years of experience with Flexforming, but also of their skill in designing a nd machining nearly all their own hydroblock tool halves. Blanks can be cut smaller, to final net size, eliminating post-cycle trimming.
Expanded forming capacity
Sixty percent of Cessna’s sheet metal parts are very small, and in 2001, the company decided to improve its efficiency with these parts by pur chasing a second Flexform press. This was a new design from Quintus Technologies, a Model QFL 1.1-800 with smaller 3.6 ft.(1.1m) diameter cir cular forming trays and shorter cycle times. The results have been very positive. As part of a conversion to lean manufacturing, the new pr ess has cut forming cycle times to 1.3 minutes, producing 120 finished parts per hour. All pressing operations have been consolidated in a single location to r educe parts handling. Production queues have been eliminated for formed parts, and the lead time has decreased from three days to one.