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Composites Manufacturer Helps Aerospace OEMs Meet Demanding Project Requirements
Tri-Mack President Will Kain holds insert-molding components used in a robotic molding cell.
Photo courtesy of Tri-Mack Plastics Manufacturing Corporation.
A specialist in high-temperature thermoplastics and thermoplastic composites sees its role as that of a valued supply chain partner that can help customers reduce costs, trim part weight, and significantly shorten lead times.
How many aircraft today are actually using non-metal parts that weigh less than their traditional metal counterparts, and can also resist the degradation caused by high-temperature jet engine environments? Although it’s hard to know exactly, the number is beginning to swell as aerospace OEMs respond to the challenge of rising fuel costs.
The drive to boost the fuel efficiency of aircraft is leading aerospace engineers today to increasingly seek strong, lighter-weight replacements for the metal materials—steel, titanium, and aluminum—that have traditionally been used in jet engine and structural aircraft components. Greater demand for durable, lightweight parts has already led to the use of thermoplastic composites (TPCs)—high-performance materials that offer high strength-to-weight ratios—for structural applications on the Boeing 787 Dreamliner, the Airbus A350 XWB, and the Gulfstream Aerospace G650.
One publisher of market research reports, Markets and Markets, recently projected the market for thermoplastic composites to be worth $9.9 billion by the year 2020, driven largely by growing demand from the transportation, aerospace, and defense industries. Engineers in these industries have found the materials to be appealing due to their superior mechanical and physical properties, which include high impact strength, high rigidity at elevated and sub-zero temperatures, and creep resistance under severe environments and constant load.
For aerospace OEMs, efforts to increase aircraft fuel efficiency via new, weight-saving materials are further complicated by the constant pressures they face to reduce cost and lead times while maintaining high quality. It all adds up to a formidable challenge that’s difficult, if not impossible, to tackle without the support of suppliers who offer not just innovative technology and materials expertise, but the ability to collaborate and help make their customer’s entire project a success.
The OEM’s challenge represents opportunity for companies like Tri-Mack Plastics Manufacturing Corporation, a Bristol, Rhode Island-based manufacturer of high-performance engineered components that specializes in high-temperature thermoplastics and thermoplastic composites for the aerospace, industrial equipment, and medical industries, among other demanding markets. With capabilities in automated composite processing, injection molding, tool making, multi-axis machining, bonding, and assembly, Tri-Mack aims to support its customers’ projects from initial concept to commercial production.
Will Kain, president of Tri-Mack Plastics Manufacturing, said in an interview with D2P that the company’s business model is “built around providing a fully integrated service to its customers.”
“It’s that whole idea of being able to be a single source, to take a part from concept—a back-of-the-napkin kind of concept—to a fully qualified process,” Kain said. “That sounds sort of simple, but there really are very few people that are doing it, at least in our industry. There might be people that can injection mold a part less expensively than we can; there might be somebody that has some trick in toolmaking, or has some expertise in machining in a certain area, but there are very few that can put the whole package together and cut out a ton of lead time to the customer.”
A hybrid bracket, made of thermoplastic composite and injection molded plastic, is manufactured by Tri-Mack at its Advanced Composites Center. Such hybrid components combine the performance of thermoplastic composites with injection molding and, sometimes, metal fastener inserts (as shown here), to create complex assemblies.
Photo courtesy of Tri-Mack Plastics Manufacturing Corporation.
Last year, Tri-Mack opened a new Advanced Composites Center dedicated to processing the latest thermoplastic composites. In addition, the company recently hired nearly three dozen new team members, adding people in engineering, 5-axis machining, account management, and human resources. “The thermoplastic composite is so new that it isn’t well known, and there aren’t a lot of people who are experienced working with it. We were very fortunate to hire an engineer who has specific knowledge in thermoplastic composites,” Kain said.
Having already doubled the size of its composites building, located across the street from its main building, the company is planning to kick off another growth project in its main building this year. The plan is to expand its engineering and material handling area in a two-stage process that would essentially double the size of the current building.
“Our business is cyclical; aerospace tends to ride the wave, and we’re definitely getting some of the benefit of the upwave right now,” said Kain. “I think this is going to be a longer growth period, and we’re trying to do it in a controlled way, knowing that we’ve lived through many up and down cycles, being conservative, but growing steadily.”
Kain credits the company’s recent growth to an upsurge in its legacy business and its early recognition of—and decision to embrace—the emerging technologies that would best serve the changing needs of the aerospace and jet engines industry.
“Some of it is legacy business and some of it is the composites,” he said. “Flight hours are up, and so our legacy parts, the injection molding and machining business, go along with that. If we’ve done our homework in the down periods, where we’ve been aggressive in quoting parts and [we call it] ‘getting on engines,’ or getting in programs that have long life, then we reap the benefits when the overall aerospace market takes off.
“But the other part is really recognizing that we needed to get into some new technologies. As aerospace and, in particular, jet engines become more and more sophisticated, they tend to run hotter; they have more loads on them, and so you have to be moving in a direction that allows you to produce parts that are going to be on those engines. If you don’t continue to develop new technology, you’re going to get left in the dust as the engine designs move. So part of our growth has been that we recognized this several years ago and got into the thermoplastic composites (TPCs).”
How Thermoplastic Composites Are Made
If thermoplastic composites aren’t well known to most people, then how they’re manufactured is even more of a mystery. But it’s an area that’s near and dear to Will Kain, who researched and set up the manufacturing process at Tri-Mack. In an interview with D2P, Kain outlined the steps that are involved in making these unusual materials.
“Think of the material (thermoplastic composite) itself, basically, as plastic-coated carbon fibers,” Kain said. “It can be woven, it can be unidirectional, it can be like a fabric. The ones that we use primarily are unidirectional carbon fiber that’s been coated in a plastic. It comes in tape—it looks like strapping tape—and it’s, say, two to three inches wide. So we take that and we lay that up according to a ply schedule for the orientation, and that’s very critical to the function of the part. The direction of the fibers is where the strength comes from, so designers design in a way that optimizes that. So they might have ply schedules that include 0 degree, 90 degree, or 45 degree lay-ups.
“Then we lay up the tape,” he noted. “A CNC tape placement machine lays down the tape and tacks it together to make kind of a soft, flexible stack. And then we put it in a press with heated platens. We heat it and consolidate it, get all the voids out under very high pressure, and make a rigid, flat sheet. So when it comes out, it’s rigid like a piece of plywood.
“Then, because it’s thermoplastic, we can reheat that,” he continued. “So we’ll shuttle that flat sheet through an infrared oven, heat it up to its melt point, shuttle it into a press, and thermoform it into whatever shape that we want to make. That’s the basic process.”
The thermoforming process that’s used is, essentially, compression molding, Kain said. “You’re taking that rigid sheet, softening it up in the oven, and compression molding it. Ours is a vertical compression molding press. The properties, when you’re done, are very similar to traditional composites that have been in aerospace for 40 years. The difference is that the glue, if you will, that holds the fibers together is a meltable resin, as opposed to a two-part epoxy. And that has some significant processing advantages because you can process it about as fast as you can melt it and reform it.”
Unidirectional carbon fibers, although very good for strong, stiff shapes, are not particularly good for making parts with detailed features. Tri-Mack’s answer is to make hybrid components that combine the best features of thermoplastic composites—using unidirectional carbon fibers for ultimate strength—with injection molding. By combining injection molding with the thermoplastic composites, they are able to produce stiffer parts with complex features—ribs, bosses, and attachment points.
“So you have a simple, very rigid composite shape, and the attachment points can be very detailed because of the injection molding,” said Kain. “We also like to combine that with insert molding, and the injection molded material can be used to kind of anchor the insert into the composite.”
Until Tri-Mack built its Advanced Composites Center, which includes custom-made machinery built for Tri-Mack, the company didn’t have the capability to work with thermoplastic composites in the way that it currently does.
Step one of the three-step thermoplastic composite manufacturing process consists of automated layup of unidirectional prepreg tape (foreground) at Tri-Mack’s Advanced Composites Center, Bristol, Rhode Island.
Photo courtesy of Tri-Mack Plastics Manufacturing Corporation.
“Everybody’s definition of composites is a little different,” Kain observed. “We injection mold very highly filled, often carbon fiber-filled resins, so in some people’s definition, we’ve been in the composites business for 30 years, or maybe all 40 years. But when we’re talking about this type of thermoplastic composites, we’re talking about a whole different kind of thermoforming process that keeps the fibers intact over their whole length, and that’s where the real strength comes from. Fiber filled resins are very strong; unidirectional fibers, where the fibers stay intact, are a magnitude stronger.
An Extension of the Engineering Team
Tri-Mack employs an array of advanced technologies, from its thermoplastic composites to a robotic injection molding cell and multi-axis machining capabilities. But the company is more than a component manufacturer, Kain said, adding that Tri-Mack assists its customers by helping them to see alternative ways of solving problems. Kain sees the company’s role as that of a “valued supply chain partner” that works as an extension of its customers’ engineering teams to help them complete their projects and meet their goals for weight savings.
“A lot of times they come with a pre-conceived notion of what they want—a molded part that is molded complete, with certain key dimensions, and so forth. We try to open up their minds to the idea that maybe there are other ways of doing it. A lot of times, especially early, we’ll figure out where they are in the process: Is this thing likely to be changed? Do we really just need a low-volume solution that will get them the first six months of production, or is this design mature enough that it’s locked in? So we’ll assess that and we’ll help open their eyes to some opportunities to have it made other ways, and a lot of times, there’s a big cost savings to them.”
Tri-Mack recently completed a project to qualify over 200 part numbers for a large aerospace OEM—at an accelerated schedule. By converting the parts from steel to TPC, the company was also able to achieve an average weight savings of 40 percent for its customer.
To help customers shorten their lead times, Tri-Mack has developed, with input from many of its customers, a new product introduction (NPI) procedure that includes a series of “toll gates” designed to ensure that important requirements aren’t overlooked in the process. “It’s everything from reviewing models or designs when they come in, looking for booby traps in those, to looking at what the quality requirements are going to be,” said Kain. “It’s about trying to really go through a formal process that looks at all those, and then it recognizes the opportunity to work in parallel.
“In our business, everything is about lead time,” he emphasized. “That might be the number one thing that gets us new business—willingness to commit to short lead times. So in the [NPI] process, even though it’s laid out in a linear series of toll gates, what we’re really doing is identifying opportunities to work in parallel. So quality will get in early and say, ‘Okay, I think we’re going to need some inspection fixtures, and this one’s going to require some particular testing.’ They can start working on that early, instead of getting handed a part at the end, adding onto the lead time. So, by trying to uncover [opportunities to work in parallel] early on, we are actually shortening the lead time because a lot of times, the lead time is spent fixing all the mistakes. I’d say that’s a key to our NPI toll gate procedure.”
Tri-Mack’s motto, ‘the best part is your success™,’ says a lot about the company’s collaborative approach to working with customers and what they’re trying to achieve. It may sound simplistic, Kain said, but he and his colleagues believe that if their customer is successful, then Tri-Mack is successful. Because they take pride in the success of the entire project, they know that there’s a lot more to their job than just meeting a purchase order and satisfying a contractual agreement. Instead, they strive to get in early on the project, understand the intent of what their client is trying to accomplish, and then work to deliver “something that will make that project successful,” Kain said.
“We love to watch the whole thing,” he said. “So, for us, it’s a really big deal when a design engineer at our customer sticks their neck out on something that’s a little new and never been done before, and then we help them be successful in that. And we have a lot of examples where we’ve been part of the customer’s success.”
Kain offered a glimpse of how Tri-Mack decides which manufacturing technologies to pursue, and where he sees Tri-Mack concentrating its efforts in the future.
“When we got into advanced composites, we really polled our primary customers and asked them what they were getting into or what they were looking at, even if it was stuff that was five or ten years down the road,” he said. “And that’s actually how we decided to get into the thermoplastic composites. We continue to have that dialogue with our customers, on what their advanced materials groups are looking at, and then we kind of triangulate in on whatever the next thing is.
“We’ve looked very seriously at the potential of additive manufacturing in our industry. There are some limitations on the strength and the amount of filler that can be in them, but we very closely follow developments in additive manufacturing (see “New Technology Enables 3D Printing of Composite Parts”). We also look at more complicated structures in the hybrid area of combining thermoplastic composites with overmolding. Those are two areas we’re strong with, and we really see a lot of potential there. We’re in fairly simple shapes at this point, but the sky’s the limit there.”
For more on Tri-Mack (trimack.com), see The Collaboration Imperative: Why it’s Critical to Your Next Project.
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