Metal fabrication skills meet needs of composites manufacturing in a range of high-tech operations.
Business is booming in aerospace and defense, fueled by record demand for aircraft and by advances in weapon systems that are remaking military capabilities.
One technology that’s playing a growing role in both industries is composites, typically carbon or glass fiber-reinforced thermosets and thermoplastics and multi-material laminates like aluminum mesh and glass fiber. These materials are essential to the performance, longevity and life-cycle benefits of applications.
Composites have become mainstream materials in many aerospace and defense programs, and their use creates opportunities for moldmakers who are more accustomed to building injection molds than wing spars, missile casings or radomes. This is because moldmakers can apply many of their skills in metal fabrication to composites manufacturing.
Demand for Machining
Obvious areas of expertise include making metal tools and fixtures for operations like reaction injection molding, compression molding and resin transfer molding, open-mold processes like prepreg lay-up and vacuum-bagging, or autoclaving.
There also is the need for high-speed machining of near-net-shape parts after they are formed by processes like filament winding or tape-laying, to meet tight design tolerances. Machining composite parts is, in fact, the operation experts say offers the most potential to moldmakers, since demand in aerospace and defense has reduced available capacity among the traditional suppliers to these industries.
“The composites market will continue to grow and expand, and there are not enough sources of supply for machining components,” says Jim Hickman, Director of Business Development at Stadco (Los Angeles, CA), a company specializing in high-tolerance parts and molds for aerospace. “Moldmakers with machining capabilities for metallic parts should be able to do an excellent job in composite machining.”
Another big plus for moldmakers is their familiarity with automation. Despite growing use, composites remain expensive. Graphite-reinforced grades with ultra-high-performance resins can cost more than $100 per pound. Automating composite manufacturing—setup, fabrication and finishing—helps reduce process cost.
Composite nose of Boeing 787 Dreamliner. Doors and windows are cut into the one-piece section after fabrication. Photo courtesy of Boeing Corp.
Some suppliers of machining centers, cutting tools and software are expanding offerings for the market. Developments include adapting machining systems for composites, designing effective cutting tools and writing software that meet a range of fabrication needs.
In a related area, suppliers are promoting equipment for machining hard metals like titanium and invar alloy, materials that are prominent in aerospace manufacturing—titanium for aircraft components and invar, whose low thermal-distortion properties maintain part tolerances to thousandths of an inch, for molds.
Stadco, in fact, has developed a process for electron-beam welding of invar tubing for use as a substructure in molds for composites. The benefit, Hickman says, is that the tubing improves airflow through the tool, so it heats and cools faster. It also strengthens the tool and reduces its weight. Stadco uses the tubing for its own work and sells it to other tool builders.
The opportunities for moldmakers in composites fabrication are very new and not always apparent to mold shops and suppliers. But there is little doubt about the demand for composites in aerospace and defense, which is confirmed by statistics that justify the enthusiasm companies have for the market.
Aircraft Programs Drive Growth
The aerospace and defense sector in the U.S. posted a 22 percent gain through the third quarter over the same period last year. Much of this is attributable to aircraft programs that are heavy users of composites for their high strength-to-weight ratio, design flexibility, damping characteristics, resistance to corrosion, fatigue and impact, and, in the case of military platforms, stealth properties.
Composite structures also resist cracks better than metallics. Joe Slusarcyk, Project Engineer at the National Center for Defense Manufacturing and Machining (NCDMM), says cracks that develop in composites do not become larger as in metals, because fibers impede their length.
Fuselage sections of Boeing Dreamliner are fabricated and then joined together, reducing parts and aircraft weight. Photo courtesy of Boeing Corp.
The NCDMM (Latrobe, PA) was formed by industry and local government to improve manufacturing processes for the Defense Dept. and its industrial base.
Recent advances in fabrication technology are moving composites from secondary applications on aircraft to primary structures, where they are used to build entire wing assemblies, fuselages and cockpits.
Aviation is one reason software provider Delcam (Salt Lake City, UT) estimates that the composites market, which it values at $15-$20 billion worldwide, will grow 3 to 5 percent annually for the foreseeable future.
The good times may roll on to 2026. According to aircraft manufacturer Boeing Corp., global demand for civilian passenger and cargo airplanes will increase to 36,420 in 2026 from 18,230 in 2006—a gain of virtually 100 percent.
Experts credit Boeing and its rival Airbus with driving demand for composites through major aircraft programs: Boeing with the 787 Dreamliner, Airbus with the A350 XWB (“Xtra Wide-Body”). The 787, scheduled for delivery in late 2008, became the first airliner to utilize a large percentage of composites in its construction—50 percent by weight. The A350, redesigned after Boeing announced the 787, will reportedly incorporate more than 60 percent composites by weight. Initial A350 deliveries are planned for 2013.
Lockheed Martin F/A-22 Raptor makes extensive use of composites for performance and stealth. Photo courtesy of Lockheed Martin Corp.
Both aircraft have had their share of delays and missteps, but are exerting a long-lasting impact on composites design and fabrication.
“Airbus and Boeing believe they are driving the leading edge of composites technology,” says Bill Hasenjaeger, Product Marketing Manager at software developer CGTech (Irvine, CA). “They’re not afraid to invest money in developing the technology, even though it’s not something they might use. They invest because it will help them build their products.”
Indeed, many companies with equipment and software developments for composites say some of these came about during work for Boeing.
The main fabrication techniques Boeing is using for the 787 involve prepreg lay-up of the wings in molds and automated tape-laying of the cockpit and multiple fuselage sections, all of which are joined together during assembly. The company cites various benefits from composites, beginning with construction. Boeing says that because sections of the aircraft are manufactured prior to assembly, it takes 2,000 workers three days to build a 787 compared to the 21 days it would take the same number of workers to construct a 767, a similarly sized, conventionally designed aircraft.
GR-408 router from Haas is for composites and metals. Features include a 10,000-rpm spindle, 40-taper milling head and 2,000 ipm travel. Photo courtesy of Haas Automation.
Composites lighten the weight of the 767 by 10,000 pounds versus an aluminum design, a factor that may reduce airport landing fees, which are based on aircraft weight.
Lighter weight contributes to the Dreamliner’s projected 20 percent fuel savings per passenger, a significant advantage considering the rising cost of fuel. According to the International Air Transport Association, the price of jet fuel in October was 42.3 percent higher than in October 2006. IATA estimates that airlines worldwide will pay $12 billion more for fuel this year than in 2006, which would sap $3 billion from their projected $5.1 billion in net profits.
The composites also will lower airframe maintenance costs by 20 percent, Boeing claims, and reduce or eliminate non-routine maintenance that in aluminum designs results from fatigue and corrosion. This means the 787 will rack up more revenue-generating flight time than conventional airliners since it will be out of service less often—a huge benefit that will be amplified by its projected life of 40 to 50 years, about double that of current airliners.
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