By Mark Shortt
Editorial Director, Design-2-Part Magazine
The rules of the sky are changing, as aircraft structural and interior parts are being targeted big-time for weight and cost reduction. New opportunities are opening up for companies that can incorporate cost-efficient manufacturing technology into part designs for new aircraft programs. This global drive to develop lighter weight, lower-cost aircraft is being felt at all levels of aerospace manufacturing today, and is responsible for a number of innovative designs. Its impact can be seen in the burgeoning development and use of advanced composite materials, collaborative design software, and manufacturing processes that trim costs while delivering high-quality parts.
Used increasingly in both jet fighters and commercial airliners, composite materials are in demand because of their ability to reduce weight while providing excellent strength and resistance to extreme temperatures, chemicals, and corrosion. At the same time that the industry is adopting advanced composite materials as a trusted solution for design challenges, it's also benefiting from digital design and product development software that enables designers and engineers to collaborate in real time across the globe.
An engineering and manufacturing program that exemplifies both trends is the fuel-efficient Boeing 787 Dreamliner, launched in April 2004 and scheduled for first delivery in 2008. Designed to consume 20% less fuel per passenger than similarly sized airplanes, the 787 incorporates "numerous technological innovations and represents a major advance in aircraft design," said Mike Bair, vice-president and general manager, 787 Program, Boeing Commercial Aircraft, in a recent statement. Composite materials are reported to constitute as much as 50% of the Dreamliner's primary structure, including the fuselage and wing, and are essential to the aircraft's higher fuel efficiency.
Reported to be the world's largest current industrialization effort, the 787 Program involves companies from some two dozen countries and 135 partner sites around the world. Boeing is using its Global Collaboration Environment (GCE) and a suite of product lifecycle management (PLM) software tools from Dassault Systemes (DS) to enable design to proceed simultaneously at all sites.
Low-Cost Process Key in Developing Inlet Duct for Jet Fighters
EDO Corporation (New York, N.Y.) recently manufactured a prototype engine-inlet duct for Lockheed Martin Aeronautics Company, prime contractor of the F-35 Joint Strike Fighter, using a low-cost vacuum-assisted resin transfer molding (VaRTM) and braiding process. EDO's work using the VaRTM and braiding process was done under the auspices of the Air Force Composite Affordability Initiative (CAI) program, established to dramatically reduce the cost of composite technologies in airframe structures. VaRTM is a flight-qualified, low-cost, high-quality infusion and molding process already used by EDO to produce airframe structures for the JASSM missile fuselage.
Characterized by a foreshortened, compact geometry with low inlet loss, the advanced-design duct has a complicated shape that poses significant manufacturing challenges. According to the company, the objective of the process demonstration was to achieve required performance and quality with the most affordable manufacturing process.
"We looked to EDO for a braided/VaRTM manufacturing approach because unit costs with this process are significantly lower than conventional methods," said Shaw Lee, Lockheed Martin's CAI program manager.
According to a statement issued by EDO, braiding was performed over a large mandrel, segmented into 35 removable pieces to permit removal after part cure. The mandrel was braided with five layers of continuous graphite fiber, with local buildups up to eight plies thick. Braiding is an automated circular weaving process that applies tensioned fibers to the part surface. EDO used its large, 288-carrier braiding machine, which reportedly allowed the duct to be produced with the desired fiber coverage without any gaps between yarns.
The duct is designed with honeycomb core inserts, which stiffen the duct wall. To ensure that resin does not fill the cell walls, the honeycomb core is filled with closed-cell foam. Reinforcing keel straps were also selectively laid up into the duct structure. A high-performance epoxy resin was then infused into the braided part using the VaRTM process. After the epoxy cures, the internal mandrel is removed from the molded part, one segment at a time. Stiffeners are then bonded to the duct exterior to reinforce the structure at key locations.
The finished duct assembly is currently being pressure tested and exposed to hammer shock tests that simulate the pressure spike associated with an engine shock wave, the company said.
Solving Design Issues with Custom Silicone Materials
An ISO-9001-certified manufacturer of custom silicone materials, NuSil Technology is positioning itself as a unique supplier to the aerospace and defense industry. NuSil often works with aerospace engineers to solve design issues through use of specially developed materials that meet end-use and processing requirements. The company's solutions include specialized silicone adhesives, sealants, coatings, and encapsulants. NuSil materials offer physical properties ranging from controlled volatility (low outgas) to electrical and thermal conductivity, fuel resistance, and optical clarity, according to Stephen Bruner, marketing director.
"Much of the work we do involves custom material formulation," says Bruner. "This requires that we have a complete understanding of the application and process. We often work with customers to help refine processes so they utilize our material with the greatest efficiency."
NuSil provides custom silicone materials for electronic and electro-optic chip packaging and sub assemblies, as well as optical and piezoelectric sensors for harsh environments. The company also provides optical interface materials for satellite applications, fuel-resistant coatings, and temperature-resistant sealants. Based in Carpinteria, Calif., NuSil operates state-of-the-art laboratories and processing facilities in North America and Europe, employs 400 worldwide, and has more than 280,000 square feet of space dedicated to manufacturing and R&D.
"We have a process that allows us to remove volatile constituents from our products," says Bruner. "We utilize this process to create low-outgassing silicone products for use in harsh or extreme environments."
The firm's controlled volatility (CV), low-outgassing materials are reported to meet applicable standards for use in space and in microcircuit applications for the Department of Defense (DoD). Because a material's potential to contaminate its surroundings is an important factor in extraterrestrial applications, Bruner says, the National Aeronautics & Space Administration (NASA) recommends that materials being considered for use in extraterrestrial environments be tested by ASTM E-595.
"ASTM E-595 subjects the material to high heat and vacuum and produces test results in Total Mass Loss (TML) and Collected Volatile Condensable Materials (CVCM)," says Bruner. "Historically, materials used in space must meet a maximum TML of 1.00% and CVCM of 0.10%."
Pac-West Rubber Products (San Diego, Calif.) employs specialty extrusion, molding, and die cutting processes to manufacture non-metallic seals and gaskets for aerospace and military applications. Parts manufactured by the company are made of silicone, rubber, and other non-metallic materials, and are used in aircraft, ground vehicles, artillery, and personnel equipment, among other applications.
One application involved the manufacture of a silicone over-coated explosive cord for rockets and satellites. Pac-West needed to overcoat the explosive cord with silicone rubber and ensure that the cord maintained its usability, according to Nick Duvall, president of Pac-West Rubber Products. The major technical challenge, he said, was to prevent the explosive cord from melting and rendering the cord useless. Another was to maintain a very tight tolerance on dimensions.
After selecting the material and obtaining the customer's approval for its use in this application, Pac-West moved its entire production line to its customer's facility and manufactured the component on-site using silicone extrusion. "We also manipulated our curing temperatures to ensure cord stability," said Duvall.
Injection Molding Delivers Lighter, Lower-Cost Parts for Aircraft
Hi-Tech Mold & Tool, a custom injection molder based in Pittsfield, Mass., recently announced that it will supply high-strength, engineered plastic injection-molded valves to Hamilton Sundstrand for the Boeing 787 Dreamliner. Certified to ISO 9001:2000 and AS9100 standards, Hi-Tech Mold & Tool employs net-shape molding and secondary machining to achieve stringent dimensional and surface finish requirements. Parts manufactured by the company include plastic components and assemblies for air-handling systems in large commercial and regional jets, as well as military fighters.
"Most of what we do are valves or valve components," says Dave Pellegrino, Hi-Tech's engineering and tool room manager. The company also molds components such as water collectors, which Pellegrino describes as a "static type" of product that takes in wet air and expels dry air.
The Hamilton Sundstrand award is the largest aerospace contract ever awarded to Hi-Tech, which estimates the value of the work at $11 million over the duration of the program. For each aircraft, Hi-Tech will build and deliver approximately 18 different valves that are essential to operating "one of the most sophisticated environmental control systems on a commercial airline," according to the company.
"This contract helps Hi-Tech's products to gain a foothold in the commercial aircraft sector, which is always looking for new ways to remove weight from aircraft," said William Kristensen, president, in a statement announcing the award. "Our high strength is working with engineered plastic resin products to provide a lightweight solution to the biggest new commercial aircraft program the industry is likely to see for some time to come."
In competing with other companies from around the world to secure the award, Hi-Tech scored points for using new engineered resins to reduce weight, as well as the cost to build and maintain the product. The materials that will be used to mold the valves are described by Pellegrino as "high-strength, high-temperature, chemical-resistant thermoplastics."
Hi-Tech has developed a reputation for using highly-engineered, carbon- and glass fiber-reinforced resins, such as polyetherketone (PEK), polyetherimide (PEI), and polyphenylenesulfide (PPS), to mold strong, lightweight parts that combine static dissipation with resistance to high heat and corrosion. The company's engineering and design team has worked extensively with customers' complex product designs to "ensure the best design for manufacturability," according to Ann Fyfe, who handles sales, marketing, and customer care.
"Most of the products that we've done are metal-to-plastic replacements," says Fyfe. "Working closely with the customer and resin supplier, we achieve quality parts with weight reduction and lower costs. Hi-Tech is a full-service supplier, so we take projects from design to final assembly, all here at our facility."
"We've already built a number of molds for the program," said Pellegrino. "From a tooling standpoint, we're about 25% [complete]. Tooling for the entire program is projected to be completed by Q1 '07. Some of the molded products are currently going through first-article inspection, and we're going to be doing the first batch of assemblies in about a month."
For aerospace/defense applications, Hi-Tech typically competes with firms that manufacture die castings, or steel and aluminum castings. Because Hi-Tech's manufacturing processes are new to these markets, it's often necessary to educate potential customers about the benefits of injection-molding lighter, lower-cost plastic parts for these applications. But by fully discussing the advantages and potential limiting factors of using injection-molded engineering plastics, customers may find that the limiting factors are not so limiting after all.
"A plastic component is not going to withstand the same types of temperatures and pressures that a metal component will, but typically, it's not necessary," says Pellegrino. "Also, extremely tight tolerances may not be achieved without machining. Hi-Tech works with its customers to create a very near net shape, and will then machine the part to tolerance."
As it looks to expand its share of the aerospace/defense market, Hi-Tech sees the Hamilton Sundstrand contract as a significant turning point, says Kristensen. It's an opportunity, he says, "to develop as a center of excellence for a completely new product range, possibly leading to additional business on other major commercial and military aircraft programs."
The company provides custom molded parts to numerous industries besides aerospace/defense, including the medical, general industrial, telecommunications, and electronics segments. Hi-Tech also makes parts for the recreational, food service, and automotive industries. The firm has presses ranging from 40 to 500 tons in clamp force, a class 100,000 clean room for medical manufacturing, and a full secondary operations department for machining, assembly, flow and pressure testing, decorating, insulating, painting/coating, and finishing.
Precision Machining and Sheet Metal Fabrication
L&P Machine, Inc., headquartered in Manteca, Calif., manufactures parts for the defense industry as a primary and second-tier contractor to the U.S. government. Parts manufactured by L&P Machine are used in applications such as weapons equipment, land systems, water systems, and space and satellite systems. The ISO 9001:2000-certified company also manufactures assembly kits for wide-body flight simulators in the aerospace industry. A specialist in close-tolerance machining, precision fabrication, and large-scale, complex assemblies, L&P provides design and manufacturing support for each project as needed.
"Each project is unique with its own specifications, concerns, and possible issues," says Jeanne Leap, L&P's sales director. "The company's role is to troubleshoot a project at the design stage, offering design guidance to help control costs and improve manufacturability."
According to Leap, the manufacturing capabilities of L&P are extensive, and reflect the breadth of more than 45 years of experience in the fabrication industry. For fabricated sheet metal, the company routinely holds tolerances of 0.005-0.030. For machined parts, L&P utilizes a variety of machining capabilities, such as CNC and wire EDM, to hold tolerances ranging from 0.0002 to 0.005. Capable of producing parts with various finish requirements, L&P is said to consistently produce "pristine brushed and mirror finish parts." The company has firm control over the final finishing step through its ownership of Eagle Finishing, Inc., a Tracy, Calif., finishing shop that provides wet painting, powder coating, and silkscreening services.
L&P Machine works with numerous materials, including metals, alloys, composites and plastics. The metals most commonly worked with include steel, stainless steel, and aluminum, but the company also has extensive experience with brass and copper. L&P works regularly with Alucabond and many high-tech plastics, such as Victrex PEEK and DuPont Delrin.
"Often, the biggest challenge is just to pull together all elements of a complex project, to ensure that all design elements are working from the same assumptions and parameters, and that all elements will fit smoothly together with no gaps," says Leap. "It's not uncommon for a specific element of a program to be 'over-designed,' resulting in tight specs that may be difficult to meet in full production."
Machining Complex Components and Assembly
Aphelion Precision Technologies, a specialist in exotic, difficult-to-machine materials, manufactures a variety of complex components and sub-assemblies for the aerospace and defense industries. The company, formerly known as Sauk Machine Works, recently added two Mazak Integrex 200-IIST machines—twin-spindle, CNC turning/milling machines with 9-axis machining capability—to its expanded, 45,000-sq-ft facility in Wheeling, Illinois. Aphelion's in-house capabilities include up to 9-axis turning with milling, up to 5-axis milling, and electrical discharge machining (EDM), as well as assembly.
"We provide components and sub-assemblies for laser targeting systems, laser range finders, aircraft electronics chassis, optics, satellite components (Mars and Pluto missions), and munitions, just to name a few," says Gene Kline, project manager for Aphelion Precision Technologies. "Seventy-five percent of what we're doing is in the aerospace and optics industries." The balance of Aphelion's work, he adds, supports medical applications like surgical instruments and orthopedic implants.
Although Aphelion primarily works with titanium and various aluminum and Stainless Steel alloys, the company also machines parts on a regular basis from materials such as Inconel, Invar, Kovar, tungsten, MP35N, GE Vespel and Noryl, and copper. Often, the parts require special finishes, such as electroless nickel or anodize, with intricate masking involved.
One of the firm's projects required it to machine an optics element component for the F-35 Joint Strike Fighter. The component, 3.75 inches long with a 2-inch radius and wall thickness of 0.05-inch, was machined from Invar material and had many cut-outs. Aphelion was able to hold the O.D. to a tolerance of 0.0004 on the thin-wall component, using roughing processes, stress relieving, 4-axis milling, and turning on a Hardinge precision lathe with air chuck.
In another case, the company machined multiple angled bores and close-tolerance diameters on a thin-walled (0.03-inch) lens corrector cell for a laser range finder. Aphelion used a Mazak Integrex CNC turning/milling machine with 9-axis capabilities to produce the complex titanium part in one operation. The ring-shaped part had a radius of 2.25 inches, a height of 0.50-inch, and wall thickness of 0.03-inch.
Aphelion Precision Technologies is certified to ISO 9001:2000 and AS9100 standards, and has been named a preferred supplier to a number of "top tier prime contractors," Kline added.
Engineering Support from Start to Finish
Parts manufactured by BHI Manufacturing Solutions, Garden Grove, Calif., are used in numerous aerospace and defense applications: hardware for aviation oxygen masks, aerospace instrumentation panels, ammunition transfer cartridges, and fuel transfer clips, to name a few. The ISO 9001:2000-registered company specializes in manufacturing custom metal stampings, springs, wireforms, assemblies, and tooling, all produced while providing what the firm calls "start-to-finish engineering and sales service." Preferring to get involved with customers as early as possible in the design and manufacturing process, BHI Manufacturing Solutions offers ongoing engineering support via e-mail and personal meetings, whenever required, "at the customer's plant or ours," says the firm's marketing director, Patricia Houston.
BHI Manufacturing Solutions manufactures parts from materials ranging from music wire and galvanized wire to stainless steels, phosphor bronze, and hard-drawn and oil-tempered materials. The company is also experienced in working with exotic materials, such as pre-plated gold, silver, and tin; Inconel, and chrome vanadium.
The company recently announced that it has completed a major expansion and upgrade of its tooling, prototype, and short run capabilities. The expansion reportedly enables the firm to produce standardized tooling to customer specifications within three to five weeks, or even sooner under certain circumstances. Among the new tool room equipment are state-of-the-art EDM machines, surface grinders, and mills. The company's prototype center also has a full line of presses, shears, and power brake. Prototypes and short-run run production orders can be completed within two weeks.
BHI Manufacturing Solutions has been audited by Boeing and certified to its D6-82479 standard, according to Houston.
Specialty Molding and Foam Fabrication
Engineering, specialty molding, and fabrication of flexible and rigid foam are specialties of Foam Molders & Specialties (FMS), a company that has served the aircraft, automotive, and various commercial industries since 1971. The company operates a 150,000-sq-ft facility in Cerritos, Calif., where it provides pressure forming, vacuum forming, reaction injection molding (RIM), embossing, precision trimming, and custom painting services. Parts manufactured for the aerospace industry include aircraft interior parts, such as foot rests and throttle housing covers, as well as air ducts, air vent grilles, and other parts with intricate detail.
"Having foam fabrication and specialty molding divisions at our disposal allows us to be a one-stop shop," says Steve Anderson of FMS. "With our size and commitment, there is no job too small or too large. We can help you finalize your design, build tooling, and produce the part."
By staying current on aerospace manufacturing processes and materials, the staff at FMS is able to work with strong, lightweight, and heat-resistant engineering plastics, including GE Ultem® (polyetherimide, or PEI). The company is also capable of forming thermoplastic sheets into three-dimensional shapes, and can handle sizes up to 144 inches x 120 inches x 0.5-inch thick while achieving tolerances of 0.030 or less.
"These are crucial requirements when dealing with plastic and composite assemblies," says Anderson. "When using reaction injection molding (RIM), we can mold virtually any shape with exquisite detail, complementing traditional injection molding."
The company's Quality Management System is registered to ISO 9001-2000, compliant with AS 9100, and approved by Boeing D6-82479.
Jet Engine Components and Sheet Metal Fabrication
Associated Aerospace Activities, Inc. (AAAI), San Leandro, Calif., is a build-to-print manufacturer of hot-section (augmentor) seals, flaps, links, and rings for military aircraft engines. Certified to ISO 9001:2000, the company has been recognized as a Blue Ribbon Contractor by the United States Air Force. In addition to manufacturing jet engine components, AAAI specializes in sheet metal fabrication, using metals ranging from "the most exotic high-temperature super alloys" to more common types. For sheet metal fabrication, AAAI is able to achieve tolerances of +/- 0.001.
Associated Aerospace Activities combines capabilities in resistance spot and seam welding, TIG welding, and press work (to 175 tons) with in-house inspection and nondestructive testing (NDT). Other manufacturing processes used by the company include fusion welding (manual and automatic); wire EDM, and CNC and manual machining. Welding, forming, and machining nickel-based super alloys are among the biggest technical challenges faced by AAAI in its aerospace manufacturing projects, according to Douglass Johnson, president.
The company will be bringing a new ABB Robotic Fusion Welding department—currently being assembled and integrated by Cassimus Company—online either later this year or early in 2007. Robotic resistance welding is also in AAAI's future. The company has plans to integrate computer tracking of resistance welding parameters—including load, current, and weld cycles—into its operations in 2007. "This will allow adaptation of SPC into the resistance welding process," says Johnson.
