The attitudes observed at a recent F-35 Lightning II Joint Strike Fighter BMI Fiber Placement suppliers conference belied the mainstream media’s often gloomy reports about and prospects for the advanced military program. The March event was the latest in a conference series hosted by MAG Americas, manufacturer of composites and machine tool equipment and systems, at its Hebron, Ky., USA, facility. The event brought together the F-35 program’s range of composites technology specialists—even competing parts producers—to share ideas in an effort to optimize efficiency and cost-effectiveness in support of the program.
The conference featured representatives of F-35 developer Lockheed Martin, including G.B. Bailey, a lead for manufacturing integration for the program. Wing and nacelle producers Alliant Techsystems (ATK) and HITCO Carbon Composites, also participated as did material supplier Cytec Industries and MAG composites customer ITT Exelis. Gardner Business Media, publisher of High-Performance Composites, was the exclusive publishing company invited to attend the event.
Chip Storie, MAG’s executive vice president, says an open forum such as this, which included the introduction of new composites processing equipment and strategies, will enable F-35 suppliers to price components more affordably for the overall betterment of the program. To that end, the conference’s highlighted piece of equipment was MAG’s new seven-axis BMI Viper automated fiber placement (AFP) machine, specifically designed for the tricky bismaleimide (BMI) prepreg material used to create critical F-35 wing and nacelle components. According to MAG, the new AFP machine is said to offer significant improvement in lay-down rate from the first generation of BMI machines deployed for the F-35 program. The machine achieves nearly six times improvement in material lay-up rate compared to earlier generation equipment, with no fuzz generation. During the event, the machine’s capabilities were demonstrated on an independent research and development (IRAD) panel used to simulate processing of an actual F-35 wing.
MAG says this improved production rate is largely due to a better understanding of BMI’s unique processing requirements. Enhancements have been made to more accurately control the temperature of the material at the lay-down point, because too much heat causes it to become molten and viscous, virtually eliminating the material’s already minimal tack qualities. The configuration of all roller and guide systems has been modified, as well, and new component materials and coatings are being used to help eliminate fuzz creation. In addition, the machine’s cut, clamp and restart (CCR) module can be disassembled, cleaned and reassembled without tools. This is said to reduce CCR maintenance operations from six minutes to three minutes. The new BMI Viper platform was developed in collaboration with ATK, which will receive the second of its two machines next month. MAG plans to offer BMI retrofit packages for its existing installed base of Viper machines, too.
G.B Bailey says what MAG is accomplishing with equipment such as the BMI Viper is just what the composites industry must have right now. “We need this type of improved productivity to become more cost-effective creating composites components for advanced aerospace applications,” he explains. “MAG is helping suppliers accomplish this especially with respect to the F-35 program. This is important because in the near future, the F-35 will be the only fighter aircraft the U.S. government will be purchasing.”
Additional machines highlighted during the conference included MAG’s Gemini dockable gantry model that is said to be the first to offer interchangeable heads to enable both tape layup and fiber placement on a single platform. This eliminates the need to base component production around the feature with the highest contour. Instead, users can achieve faster production rates by tape-laying with wider material where appropriate and switching heads only when necessary to fiber place with narrower material to create tightly contoured features. Head changeover takes less than two minutes, the company says. And by fitting the machine with a cantilever cross rail, head docking stands can be located outside the workzone at any point along the 35m/115-ft X-axis travel to minimize movement when changing heads.
One of the company’s new low-rail Charger tape layers, which was also shown at the conference, is the first such U.S.-made machine to be delivered to China. It was selected by Shanghai Aircraft to produce wings, horizontal stabilizers and central wing boxes for the COMAC C919 and C929 commercial passenger jets. The Charger can be set up to run 3-, 6- or 12-inch (76, 152 or 204 mm) tape and has the widest cross rail the company has produced for a tape layer at 8m/26.2 ft. When installed, it will offer 25m/82 ft of X-axis travel, 1.2m/3.9 ft in Z-axis and A-axis rotation of ±25°.
Composites machining systems were also highlighted at the conference. The Precision AutoDrill System applies technology from MAG plants in Fond du Lac, Wis., USA, and Hebron. This system combines an FTR boring mill with an Autodrill ram, carrier and head. The machine seen in build will be delivered to Boeing’s South Carolina facility for drilling and trimming of 787 fuselage barrels. Combined with a rotary indexer, it will be used to trim fuselage windows, doors and end connectors as well as drill more than 1,000 holes per barrel. It features an on-board toolchanger to enable tool changes to be performed in 30 seconds no matter where the head is located along the machine’s 12m/39.4-ft X-axis range. Plus, this is the first composites mill to be delivered with cryogenic, liquid-nitrogen through-tool-cooling technology.
Finally, the conference featured two of the company’s Precision Mill and Trim (PMT) gantry mills to be delivered to Triumph Aerostructures. These machines are said to be more robust than routers commonly used for composites trimming and more precise through use of scales on all five axes. In fact, the two machines at the conference will be used to trim and drill aluminum fuselage sections for Boeing 747 and 777 aircraft. PMT mills can be outfitted for wet machining or dry machining when using a proprietary vacuum shroud and ducting design for effective dust control. To minimize energy consumption, the mills have only one hydraulic system, which is used to actuate the spindle drawbar.
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