Solving Aerospace Manufacturing’s Complex Riddle
Three AS9100 certified contract manufacturing suppliers discuss their strategies for ensuring product quality and safety.
By Mark Shortt
Aerospace manufacturing is known for its high degree of difficulty, with accompanying standards for quality that few industries can match. Much of this aura stems from the harsh environments in which aircraft parts operate–like the high pressure and temperature extremes of jet engines–and the uncompromising safety standards that govern the manufacturing of aircraft.
That high bar is apparent when you see samples of aircraft parts with complicated geometries or constituent materials that are notoriously difficult to machine or weld. Some are high-performance parts that resist corrosion, while others are “hybrid” composite parts that are strong, yet light enough to meet fuel efficiency requirements. The processes used to manufacture composite parts–such as those that combine plastics with fiberglass or carbon fiber reinforcements–can be particularly challenging, as well as notoriously slow and expensive.
Aero Gear manufactures gears and gearbox assemblies used in jet engines all over the world. Photo courtesy of Aero Gear.
Innovative technologies, like software and automation, bring undeniable benefits to manufacturing, yet they also pose challenges for manufacturing engineers. Connected and software-embedded products introduce new vulnerabilities. They also require greater collaboration with the design team to ensure design intent is met and the product meets specifications. Sensors and other critical components need to be thoroughly inspected in real time to eliminate defects.
Regardless of their difficulty, aircraft parts must be made with unwavering precision. All stakeholders throughout the supply chain–from prime contractors to tier-3 suppliers, contract manufacturers, and job shops–are keenly aware that the safety of aircraft passengers depends on parts that are produced to exacting quality standards. And so they are left to solve an engineering and manufacturing riddle that goes something like this: How do you achieve the highest quality requirements when aircraft materials, parts, and production processes are now more complex and more challenging than ever?
Aero Gear, a contract manufacturer that produces precision gears and gearbox assemblies for aerospace giants like Pratt & Whitney, Sikorsky, Boeing, and General Electric, has developed strategies that have worked well for its customers over the years. Last June, the company completed a 24,000-square-foot addition to its facility that Aero Gear President Doug Rose said was necessary to keep pace with the industry’s robust demand for jet engines, the primary application for its parts and assemblies. The addition increased Aero Gear’s total space to approximately 100,000 square feet, which includes manufacturing space for several new programs.
“We’re a small company, but we have a big impact on the industry because our gears are out there flying in commercial and military aircraft, in thousands of planes a day,” Rose said in an interview at Aero Gear’s manufacturing facility in Windsor, Connecticut. “We started out as just a local shop making parts for companies like Pratt & Whitney, and then, as globalization came about, we embraced it and went looking for opportunities. Now, we do 30 percent of our work internationally, exporting.”
Monitoring and Controlling the Process
Rose, a degreed mechanical engineer who started the company in 1982 with one employee, said that Aero Gear ensures the highest quality of its parts by carefully controlling and monitoring its processes. A quality control person is embedded in each manufacturing cell to make sure the process is consistently producing good parts, and to document that the parts are free of defects. It’s a far cry, he said, from the old school practice of waiting until all the parts have been machined before inspecting them at the end of the process.
To help make the inspection process less manually intensive, the company invested in white light scanners that enable workers to check critical diameters and lengths–not just the external features–of a part very effectively. Rose said that Aero Gear is in the beginning stages of integrating this inspection technology with its CNC machining systems.
“We’re starting to link up some of the inspection equipment to the machines,” he said. “The scanner, and, in some cases, the CMM, can feed back to the machine and make adjustments.” Some of the firm’s machines also have a probing arm that allows the part to be inspected as it’s being manufactured. “Basically, it comes down to always monitoring the quality [of the part] as you’re making it,” he said.
Aero Gear was recently awarded “Elite Supplier” recognition from its longtime customer, Lockheed Martin Sikorsky Aircraft. It marked the second year in a row that Lockheed has chosen the company for the award, which honors consistency, reliability, and resourcefulness. Aero Gear’s superior product development and support service also earned United Technologies Corporation’s rank of “Gold Supplier” for a second year.
Most of Aero Gear’s processes, including machining, grinding, vacuum carburizing, superfinishing, balancing, and nondestructive testing, are performed in-house. It’s part of the company’s Lean philosophy of flowing its product to reduce lead times.
“Whatever operations or processes we need to make the gear, we do as much in-house as we can so that we can flow the product and be a time-based competitor,” Rose said. “That’s our strategy. Some companies will specialize in machining and subcontract the rest out. But we like to do as much in-house as we can because you’re controlling the process and you’re controlling the flow.”
Maintaining Critical Case Depth on Gear Teeth
Rose said that Aero Gear’s core competency is its knowledge and command of the processes needed to maintain case depth on gear teeth. Effective case depth, according to ASM International, is “the distance between the finished tooth surface to a specific subsurface hardness value.” It is essential to producing “a gear that can withstand a sustained, applied load,” according to the global materials information society.
“It’s a real niche for us,” Rose said. “We do our own heat treat in-house because we want to control distortion, and it’s very important to control distortion in order to maintain case depth on gears, which is really critical.”
The ability to maintain case depth on the gear teeth requires knowing, first, what the configuration of the part should be prior to its being heat treated. Then, it’s necessary to determine what controls should be used on the heat treatment process, to ensure optimal heat treatment while minimizing distortion.
“You’re controlling distortion within a few thousandths of an inch,” Rose said.
The gears are then finish machined, which is likely to mean that only five thousandths of an inch (0.005 inch) of material should be machined to maintain case depth on the part, Rose said.
“Very few companies know how to do that well. That’s our niche in aerospace gearing, and I would say that’s our core competency. You couldn’t be just a regular machine shop and make the gears that we do and subcontract out the heat treat. You wouldn’t be successful.”
Wanted: Detail-Oriented Team Players
As Rose looks back on his years as leader of Aero Gear, the biggest difference he sees in the aerospace gear manufacturing company today, versus 25 or 30 years ago, is its team-based approach and commitment to harnessing the skills and abilities of everybody in the company. “Of course, the technology on the machines has really come along, too,” he said. “But you have to harness all that technology through teams of people.”
Rose said the company really took off around the year 2000, when it fully embraced a Kaizen, Lean Manufacturing approach. It was a breakthrough of sorts that formally established a way of working on Continuous Improvement by involving teams of people working together. All that work paid off in new contract after new contract, leading to last June’s expansion.
“To me, it’s just been amazing how much more you can accomplish with an engaged team, than with individual performers doing their tasks. For me, the change has been about that, and having the mentality of Continuous Improvement–you can always do it better. It all goes to viewing everything as a process,” Rose said.
Aero Gear’s team-based approach is a key reference point when evaluating job applicants. Its team includes–among other personnel–gear designers, gear grind operators, manufacturing and quality engineers, skilled machinists, and CNC programmers for its machining centers. Beyond establishing whether a person has the basic technical skills and aptitude, Aero Gear does personality profile testing to help determine if an applicant will be a good fit with the company.
“You have to have certain basic [technical] skills to enter the workforce here. But once you have the basics, then it’s about being team-based and being detail-oriented to do a good job,” Rose said. “In our industry, you have to be high-detail: You have to pay attention to detail and ‘sweat the details’ to be successful.”
Flexible Manufacturing System Increases Adaptability, Precision
Four years ago, L&R Precision Tooling Inc. received its AS9100 certification, affirming that its quality management system meets the international standard for the aircraft, space, and defense industry. A machine job shop in Lynchburg, Virginia, L&R Precision Tooling specializes in machining complex parts in titanium, Inconel, and other exotic materials to tolerances of plus or minus 0.0002 inch. Its 5- and 7-axis machining capabilities enable the company to produce complex parts with fewer setups of its machines, saving time and increasing productivity and predictability.
L&R Precision Tooling’s Fastems Flexible Manufacturing System is well suited to handling the part quantities and fluctuating delivery schedules that are common in the aerospace market. It is currently configured with three Okuma MB4000 horizontal machining centers and capable of holding up to 52 pallets. Photo courtesy of L&R Precision Tooling.
These multi-axis machining capabilities and experience in working with exotic materials, particularly Inconel and titanium, put L&R in a strong position to serve the aerospace market, said Chris Coffey, L&R Precision Tooling’s vice president of business development.
“We have always excelled at taking on complex parts in a wide variety of materials, which led us to performing a lot of machining in numerous Inconel alloys for the oil industry,” Coffey wrote in an emailed response. “After the Deepwater Horizon spill in 2010, the requirements for traceability of materials and inspections in the oil and gas industry became much more stringent, and it was great preparation for transitioning to AS9100 and the requirements of the aerospace market.”
In recent years, L&R has added new equipment with an eye toward not only creating capacity, but increasing flexibility, adaptability, and precision. A prime example is the company’s Fastems Flexible Manufacturing System, currently configured with three Okuma MB4000 horizontal machining centers and capable of holding up to 52 pallets. Well suited to handling the part quantities and fluctuating delivery schedules that are common in the aerospace market, the flexible manufacturing system (FMS) meets the needs of customers who don’t want to carry inventory but want to be able to achieve volume pricing on smaller batches of repeat parts.
“The FMS works well for the aerospace and aviation markets, as they typically don’t need large runs of parts–they need smaller batches for just-in-time delivery, and that’s the sweet spot for this system,” Coffey told D2P in a 2017 phone interview. “The beauty of the system is that programs and fixtures can be stored for immediate retrieval to more quickly move back into production for varying quantities of parts, while providing predictability in pricing,” he wrote in an emailed response in March of this year.
He also explained that integrating the flexible manufacturing system with three Okuma MB4000 horizontal machining centers provides “very stable platforms for precision and repeatability, with features such as thermal compensation, spindle load monitoring to automatically adjust speeds and feeds, and onboard probing.”
L&R Precision Tooling has a nucleus of people who have contributed greatly to its success, Coffey said. Eleven of its employees have been with the company 15 years or longer; another three, more than 10 years. A company that is partially owned by its employees, L&R looks for machinists who take great pride in their work and show great attention to detail.
“We strive to bring on employees who understand ownership mentality and what that means for us as a whole, and for them and their families,” he said. “Attention to detail is very important, so we look for people who are not only good machinists but understand the importance of what we do. They should show an eagerness to learn and can push a machine’s capability to its limit.”
Part of L&R’s philosophy is to provide its machinists with the quality equipment and tooling required for them to excel at their jobs.
“We believe the process is a combination of 50 percent machine and 50 percent skilled machinist, as each complements the other,” Coffey said. “We strive to maximize the potential of both.”
In addition to being certified to AS9100 Revision D, L&R Precision Tooling is compliant with International Traffic in Arms Regulations (ITAR).
Aerospace Platforms, Tooling, and Ground Support Equipment
A custom metal fabrication firm in O’Fallon, Missouri, WB Industries (WBI) designs, engineers, and manufactures a wide array of custom platforms, tooling, and ground support equipment used by major aerospace manufacturers. The company recently earned its AS9100:2016 Quality Standard Certification and is a Boeing Gold Level Supplier, having won numerous Boeing Supplier Excellence Awards for quality and on-time delivery since 2007.
“We couldn’t be prouder as an organization to earn this exceptional quality standard certification,” said WB Industries President Gary Bertolucci, commenting on the company’s AS9100:2016 certification in a prepared statement. “This certification expresses our attention to detail and our commitment to strive for continual process improvement and consistency.”
A metal fabricated work platform manufactured by WB Industries for an aerospace customer. Photo courtesy of WB Industries.
WB Industries uses its welding and precision machining capabilities to manufacture aircraft platforms that include personnel access platforms, emergency egress structures, and platforms for assembly, painting, testing, and maintenance and repair. Tooling equipment manufactured by WB includes assembly jigs and fixtures, drill jigs, and holding fixtures.
For customers that need ground support equipment, the company builds products like parts handling carts and storage racks, hoisting and lifting fixtures, conveyors, turntables, and stabilizing jacks and stands.
Improving Safety and Efficiency
“Everything we build has to have the utmost of safety built into it,” Bertolucci told D2P in a phone interview. “We’re not, typically, doing a lot of what I call large volume, fly-away parts. We’re focused on the ground support equipment, the tooling, and platforms that help our customers produce the parts.”
Often, a customer will come to WBI with a request to modify a platform or holding fixture that WBI had built for them years earlier. The reason, Bertolucci said, is they’re looking to improve efficiency and safety.
“They’re constantly looking at their assembly line, figuring out how to cut a few minutes from production here and there because of the high cost of building these products,” Bertolucci said. “They’re always looking to increase their efficiency and to make these products easier and better for their in-plant employees to work on.
“And, of course, the bigger issue for all of us is safety–it (the product) has to be safe all the time. So, the two big needs that they’re coming to us with are ‘We need something efficient, and we need something that absolutely ensures safety.’”
Waterjet Cutting Is Key to Quality
WB Industries’ machining services for the aerospace industry include CNC precision machining, tool manufacturing, and metal cutting. In recent years, WBI acquired a Kuraki horizontal boring mill, which it uses to machine larger parts, and a Flow Mach 3 waterjet cutting machine, which Bertolucci said offers outstanding precision and quality.
“Waterjet cutting is slow but is extraordinarily precise,” Bertolucci said. “It’s costly, but it’s an absolute necessity to make the kind of quality that’s expected from us.”
WB Industries has used plasma burning and laser cutting for various applications in the past. Although both processes are significantly faster and less costly than waterjet cutting, Bertolucci said, they present challenges in meeting customer specifications because they create a heat affected zone (HAZ) that distorts the material that’s being cut.
“With the waterjet, you don’t have that heat affected zone,” Bertolucci said. “We can’t afford to have material distort. That requires expertise on our welding side of things, but also making sure that we’re bringing the absolute best initial products, cut products, into the system. So, we need to ensure that we’re going to have a perfect part, with very little work that has to be done at the end to make sure that we’re meeting the tolerances.”
WB Industries Vice President and General Manager Ken Wasiuta, a mechanical engineer, said that when it comes to CNC precision machining, versatility is probably WB Industries’ greatest strength.
“We can machine contours, we can machine fairly large flat surfaces, and we do very small, intricate tools that you can hold in your hand,” Wasiuta said. “We have the ability to machine quite a variety, and that’s what our customers really expect of us: We don’t machine the same part over and over again.”
Wasiuta said WBI got its start within the aerospace industry making small components with detailed, complex tools, and progressed over time to its current capabilities.
“We started to do small, complete tools, which encompassed all of the different types of fabrication that were needed–the saw cutting, the welding, the machining, the painting, the final assembly. And over time, these tools got bigger and more complex. If you look at 2018 for us, it was really a lot about maintenance platforms and other structures needed to get workers close to the aircraft that they’re working on.”
Wasiuta said the year brought WBI jobs that encompassed just about every imaginable variety of platform and shape, from simple rectangular platforms to those with very complex shapes that match up perfectly to the contour of the aircraft; platforms that went up and down; platforms that floated on cushions of air; and platforms that had all kinds of utilities and other unique features that gave the operators–the fabricators at its customer’s factory–everything they needed at their fingertips to do whatever it was they were doing.
“That’s a big part of our business, making those platforms and related structures that get people close to the aircraft and keep them safe,” Wasiuta said.
In the category of tooling, WB Industries makes complex tools–including high-precision assembly jigs and drill fixtures–that are used to make the aircraft. They must be very precisely made, Wasiuta said, because they will ultimately determine hole locations or component placement. “They have to work with the assembly that our customers do. It all has to work together.”
The ground support equipment that WBI manufactures is also tooling that’s used in the manufacture of aircraft, but it’s not directly used to make the aircraft part.
“It’s accessory pieces, it’s lifting and hoisting tools, things like that which allow you to pick up a complex-shaped airplane part and safely move it from one location to another,” Wasiuta said. “It’s shipping and storage carts of all types. We’ve done very small, suitcase-size shipping containers to tools as big as school buses that are used to hold and transport very, very large parts for commercial aircraft, from one side of the country to the other.”
Complex Work Requires Design and Engineering Expertise
Design and engineering expertise, as well as the ability to collaborate with customers, is important to WBI because of the complexity of its work. The company added this capability over time, as its reputation grew with its aerospace customers, Wasiuta said. Today, WBI’s team includes design engineers, stress analysts, and highly skilled CAD operators who can work in the 3D CAD realm and produce drawings that its customers want to see.
“We’ve got a good capability right now; we know how to do design in the aerospace realm,” he said. “We have the software that our customers are using, and we understand how they design. We can talk their language and do it in a way that they’re familiar and comfortable with.
“Being a design capable supplier to aerospace companies is a demanding thing all on its own,” he continued. “Some companies just provide designs. We do that, but we also back it up with an in-house fabrication capability. So, our customers can have a one-stop shop: They can get the design done here and then they can send their representatives out at a later point and look at it being built, which is of value to our customers as well.”
Wasiuta said that customers are coming to WBI more and more now with very loose concepts of what they want to be built. Initially, when WBI started designing, customers would give them detailed concepts on paper, or a model.
“They would tell us, ‘This is kind of what we’re looking for. Go ahead and take it from here.’ But in the last couple of years, they’re just giving us a written description of what they want, and some background, and we have to take it from there,” he said. “It took some time for them to develop that trust, and we’re seeing that on a regular basis now.”
WB Industries’ engineering work begins when customers bring the company their statement of work: what they need from WBI. Often, the customer may not have any idea of what the product might look like. It’s WBI’s first order of business to solve the technical statement of work challenge. Once that’s accomplished, WBI begins a second stage of engineering design, where it conducts design for manufacturability, design for cost effectiveness, and design for maintainability.
“There’s definitely a process that takes several iterations,” Wasiuta said. “A number of different design reviews are held to make sure that you have a technical solution, but also one that is manufacturable and maintainable. It has to use the maximum amount of commercially-available, off-the-shelf parts, so that spare parts are readily available. Customers want preventive maintenance plans; they want listings of products that could wear out and have to be replaced.
“So, it’s an involved process and then, at the end of it, you end up with something that technically solves their statement of work in as elegant, clean, and simplistic a way as possible. And that’s ultimately the art of design. That’s when you’re not just engineering, but now you’re entering into the art side of it.”
Newer Technologies, Materials Taking Hold
Wasiuta said that additive manufacturing is now being discussed within the aerospace industry as a technology that could help companies do quicker prototyping. And the rising demand for non-standard materials–specifically composites–in airplanes is pushing suppliers to extend their capabilities. For WBI, that means supporting tools that are used to make composite parts, and welding on materials that have traditionally been atypical for them.
“We’re having to support tools that go in autoclaves, and tools that have vacuum components to them, that are machined in such a way that you could lay uncured composite components on and have them take a particular shape,” he said. “That requires skills that we haven’t seen before, so we’re developing the expertise and coming up to familiarity with those types of tools.
“We’re also being asked now to weld on the types of materials that are used on the composite tooling, such as Invar materials, and different, more critical grades of aluminum and alloy steels for the different tools that go into that. So, we’re always being pushed and extended, and it’s no different now than it was 15 years ago when we started into our aerospace work. We’re a far cry more capable now than we were back then, and I imagine in five years, we’ll be doing things then that we’re just thinking about now.”
Although technical expertise is essential in engineering and manufacturing, Bertolucci also realizes the importance of the interpersonal element, or the human element, in a very technical field.
“It is vital for us, if we are going to be a long-term source, that we have to maintain our employees here,” he said. “And so, we work very, very hard on employee engagement, trying to make sure our employees here, internally, believe in what we’re trying to accomplish, and that they understand and trust each other. There’s so much documentation and processes that we have to follow, that if we don’t have the utmost trust from one handoff to the next handoff to the next handoff, by the time it gets to our end game, we’re not going to be a very successful company.
“So we work very hard on the employee engagement part to make sure that every group and every area in our company trusts the area that’s handing off that next bit of work to them, so that we can work on things positively and not waste our time trying to point fingers and trying to figure out where the problems are. We want to recognize that we’re all going to do this with the same sort of approach, the same sort of intensity that’s going to ensure that at the very end of the day, our clients see a great finished product.”
Using 3D Printing as a Tool for Solving Problems
Kevin Dyer, founder and CEO of InterPRO Additive Manufacturing Group, said that it’s rare for his company to use 3D printing to make a presentation model for an aerospace customer. Instead, InterPRO is more likely to print a part to be used in an engineering study or analysis. The 3D printed item might be used as a flow model to test the performance of a particularly shaped component through which air or liquid will pass.
“We’re mostly in prototyping, engineering, and testing, and getting answers to things, as opposed to deliverables such as flight-certified hardware, which would require extremely high tolerances,” Dyer said in an interview at InterPRO’s facility in Deep River, Connecticut. “We’re in that kind of gray area, where we’re helping customers engineer and solve problems, as opposed to producing something that’s going to go have flight-critical requirements.”
InterPRO is a 3D printing service provider that uses a variety of processes to produce custom parts on demand. The company’s capabilities include making parts via stereolithography (SLA), HP Jet Fusion, Fused Deposition Modeling (FDM), selective laser sintering (SLS), PolyJet, and direct metal laser sintering (DMLS).
One of the company’s projects involved building a facsimile of an HVAC system’s piping to help a customer that had been experiencing problems with its environmental control system. Condensation that had formed within the customer’s HVAC system was escaping the system and causing damage to circuit boards, and so the customer needed to pinpoint where it was originating.
“They didn’t really know why it was happening, so they had to track it down,” Dyer said. “It was a very big problem. We worked with them to build a facsimile of the HVAC system’s piping, so they could actually see where the condensation was taking place.”
Dianna Niziolko, InterPRO’s sales manager, said that aerospace customers are showing interest in using additive manufacturing to fabricate jigs, tools, and fixtures–some of them color coded to indicate a particular use or function–for use in their manufacturing operations.
“They don’t have to worry if it’s flight certified, or if it’s flame retardant,” Niziolko said. “They can just say ‘I need a colored jig that’s going to have a QR code on it.’” When the part is sent to the shop, “someone takes their iPhone and scans it, and they know exactly what assembly they have to do.”
In one case, InterPRO sold a Markforged 3D printer to a company that makes airfoils. InterPRO had been making parts for the company before the firm decided that it needed its own machine. “We introduced it [the machine] to them, and they started to design their jigs and tools for holding the airfoils and processing them in a way that they had never done before,” Dyer said.
Niziolko agreed that customers often come up with new ideas for using their 3D printer once they have the machine in their facility. They may have come to InterPRO thinking they have one application that will pay for their machine in a year. But when InterPRO follows up with them a few months later, that’s often no longer the case.
“Three months later, they’re doing 60 other things with it that they never imagined possible,” she said. “If you plant the seed, it’ll grow. It’s really about getting the engineers involved and putting that tool in front of them. It’s not like ‘This will make widgets.’ It’s more like ‘This is a tool for your tool kit.’ We’re a partner for growing your knowledge in additive manufacturing.”
For more on InterPRO, see New Materials, Technologies Herald Bright Future for 3D Printing.
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