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Sky-High Precision
Stealth jet specs are as fine as 0.004 inches
Terry Costlow -- Design News, September 13, 2004
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| The supersonic Raptor's components are so precisely manufactured that wings can be replaced in the field. |
For decades, military products set the pace for reliability and durability requirements. Now the industry is among the industries raising the standards for precision manufacturing -- thanks to extensive use of vision systems.
Delta Sigma Corp. of Acworth, GA assembles the fuselage of the F/A 22 Stealth fighter plane, an aircraft built to travel at supersonic speed over long distances, yet still permit field installation of parts as significant as wings. Creating a plane that meets these sometimes conflicting requirements demands close attention to detail--a process President Roger Richardson described in his keynote speech at DVT's Global Business Conference and User Group Meeting.
The sub-contractor is responsible for linking two parts of the fuselage together, a step that becomes even more critical than normal since the Raptor’s replaceable wings attach to these fuselage segments. That requires an advanced production line. “The fuselage halves must be perfectly aligned or the wings cannot be attached,” said Richardson.
He notes that the portions of the jet’s fuselage must be aligned to within 0.004 inches, something his company is able to accomplish using vision systems from DVT. The plane undergoes half a million pounds of force when a fully loaded jet does a 9G turn, so “we have to have a system we trust. We’ve built a production line with 16 cameras operating on 96 degrees of freedom,” Richardson said. Another challenge for meeting these close tolerances is that the fuselage halves are built in different states before being assembled in Georgia.
The cameras are removed during drilling, so the production line has to be very versatile, providing easy changes while still meeting the fine tolerances. A number of pins help align the vision system, lights and the fuselage components. Strobe lighting is used to provide exact location information.
During its portion of manufacturing Delta drills 5,800 holes. The company also tests the surface coatings that help give the jet its Stealth characteristics.
