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Good Times in Thermoplastic Composites

By Karen Haywood Queen Contributing Editor, SME Media

Aerospace, automotive, energy, medical market segments can all benefit

Thermoplastic composites are gaining traction in manufacturing applications, offering benefits like lighter weight, faster production times, longer shelf life and easier shipping compared with metals or other composites. In some thermoplastics, design, branding and the appearance of texture now can be made part of the material itself.

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Tom Kneath (far right) looks on as the Tri-Mack team proves out its hybrid overmolding process using a robotic molding cell. “By combining UD thermoplastic composites with injection molding, Tri-Mack is able to produce complex hybrid parts that feature the advantages of both technologies,” he said.

Manufacturers are optimistic about growth for this four-decades-old industry, especially in the aerospace, automotive, light rail, medical and oil/gas sectors.

“We’re working on some programs in thermoplastics that could double or triple our business in thermoplastics in a year in commercial aerospace, oil and gas, and automotive industries, just to name a few,” Mike Buck, product manager for thermoplastic composites (and former CEO) at Barrday Composite Solutions, said.

Sekisui SPI also is bullish about growth based on use of its thermoplastics with its new Infused Imaging technology in aviation, mass transit and healthcare.

“By 2030, we expect there will be 3 billion additional people in the middle class sector globally, Karen Brock Amoah, VP of global commercial strategy at Sekisui SPI, said. “That’s going to drive growth in aviation and all forms of travel. The middle class wants to get out and travel. You also need a health care system to support this global growth in the middle class. This coming growth is unprecedented.”

Infused designs building excitement

Sekisui SPI’s Infused Imaging embeds imagery below the surface and throughout a thermoplastic sheet, much like a tattoo, she said. The new technology emerged first for the aviation industry. In 2016, Sekisui SPI won the international Crystal Cabin Award for excellence in aircraft interior innovation.

The product has been used in airline seats, seatback document holders and in other areas on airlines, including Air China and United, the company said.

“We have some samples we designed specifically for aircraft interior components, such as seating, tray tables and in-flight entertainment that look really high end,” Amoah said.

Infused Imaging replaces capping, where a design is applied to a thermoplastic sheet by adding a cap layer, she said. But when that capped surface is dinged or scratched, the entire object appears worn or broken.

“Not only was it the weak link, but it complicated the whole value chain,” she said.

With Infused Imaging, the unique, bespoke designs are integrated into the thermoplastic sheet, become part of the base resin itself and, thus, will not crack, rip or fade, Amoah said.

Infused Imaging makes a higher aesthetic possible in custom design with patterns, colors and effects, she said. The company also can offer its product in small minimum orders of 600 pounds compared with up to 1,000 to 5,000 pounds from other companies, she said. This has allowed airlines and other companies to customize products, perhaps creating one look for customers in Asia, another for those in Europe and still another look for those in North America.

Because Kydex sheet with Infused Imaging retains all the mechanical properties of sheet, it also meets all FAA standards for fire, smoke and toxicity, the company said.

After starting in aviation, where many of these new materials are first used, demand and use is expanding to other industries, Amoah said. In mass transit, the rail industry is looking for lightweight solutions to customize dining cars and others areas for a durable, upscale appearance.

“Some of these dining cars have a unique bar area that the rail lines are trying to brand so they look unique,” she said. “Our infused image gives it a high-end, bespoke look.”

Sekisui SPI also is looking at expanding Infused Imaging into the medical sector, with a goal of making the housing for complex, cutting-edge machines, such as those that produce MRIs, look as state-of-the-art as the equipment inside. Compare it to advances in the technology of household ‘white goods,’ such as refrigerators and washing machines, which now come in silver, black, red and other colors.

“Traditionally, medical housings have been white with not a lot of thought going into the exterior,” she said. “Now original equipment manufacturers are beginning to realize that the white exterior doesn’t always match the state-of-the-art robotics technology that’s inside. They want to make it look more futuristic, more design intensive with unique colors and textures.”

Thermoplastic advantages over metals

Compared with metals, all composites enable manufacturers to reduce weight, a key driver for automobile, aerospace and rail industries.

By using composites, OEMs can save 40% to 70% on weight/mass, Tom Kneath of Tri-Mack Plastics Manufacturing Corp. said.

“Much of our chopped fiber thermoplastics ends up going into the automotive space,” Mark Minnichelli, director of technical development, performance materials division, at BASF Corp., said. With less weight, cars and trucks more easily meet fuel economy standards, he said.

“Light-weighting in vehicles has been a huge driver for thermoplastics to replace heavier metals in automobiles as automotive companies work to meet new federal fuel economy standards,” Minnichelli said.

In 2015, BASF worked with a Ford Motor Co. and Magna International to create the first carbon fiber reinforced, injected molding grill opening reinforcement (GOR), Minnichelli said. The new GOR is 24% lighter than the one it replaced.

Sekisui SPI has estimated that using Kydex 6565 thermoplastic sheets in aircraft seats can lower the weight of each seat by 25%, saving fuel, Amoah said.

Complementing metals

In some cases, thermoplastics are reinforcing metals instead of replacing them, Rob Lyons, senior manager for lightweight composite technologies performance materials division at BASF Corp., said.

“In many cases, we’re not directly replacing a part,” he said. “Instead, we’re complementing a material that’s already there. You can down-gauge (reduce the weight of) a steel panel by reinforcing it with a thermoplastic composite.”

In a car wreck under the resulting extreme loads, metal tends to buckle and lose some of its performance capabilities, Lyons said. By reinforcing a metal panel with thermoplastic to prevent that buckling, “we can do a better job of managing crash energy.”

“We’re not out to replace every bit of metal,” he said. “In some cases, we can complement metal and make it perform even better.”

Advantages over thermosets

Thermoplastic composites, which are processed with heat, also offer advantages over thermosets, which are chemically cured to change from liquid to solid form.

Compared with thermoset composites, Kneath and Buck said, thermoplastic composites are:

  • Easier to ship and process;
  • Eliminate the need for freezers;
  • Do not expire, and
  • Conducive to automated processing with shorter cycle times

“You have to keep thermosets in the freezer and have to pack them in dry ice to ship overseas or put in a frozen container,” Buck said. “Once you take thermosets out of a freezer, you have to use them within a certain period of time. As the name thermoset implies, it sets. It can go bad on you sitting out.”

Manufacturers using thermoplastics can make their parts faster, Buck said.

While a thermoset part may cure as quickly as three to five minutes, a part made with high performance thermoplastics doesn’t need to cure at all and thus can be ready to go in less than a minute or two, he said.

That timesaving makes a huge difference in automobile manufacturing. Not surprisingly, automakers already are the largest user of thermoplastic composites, Buck said.

“In the automotive world, a five-minute cure rate may equate to the ability to produce 50,000 parts a year,” he said. “If you’re making a half million cars, even a three- to five-minute cure rate is too long. You need to make them faster. That’s where thermoplastics come in. In my opinion, part making is going to drive thermoplastics in the future, especially in high-volume manufacturing.”

Compared with thermosets, thermoplastic composites often provide a lower moisture absorption, higher resistance to chemicals and solvents, better wear resistance, more impact resistance, and are more easily recyclable both during manufacturing and post-use, Buck said.

If a complex shape is needed, parts makers can run the same flat sheet through an additional heating process and press form the shape, Kneath said.

That ability often helps manufacturers reduce the number of components required in any particular part, Lyons said.

“Some applications in metal that require up to10 components, many linear feet of weld and multiple operations to assemble can be reduced to three or four thermoplastic composite parts,” he said. “In some cases, we can take three or four components and reduce it to a single one.”

Fewer moving parts equals better reliability. “Most people who study design for manufacturing would say fewer components means fewer chances for misalignment, fewer chances for mis-opereration in terms of welding, fewer costs in inventory,” Minnichelli said.

Continuous vs. chopped

Finally, advanced continuous fiber thermoplastics offer mechanical properties that are significantly higher than those in chopped fiber thermoplastics, Kneath and Minnichelli said.

These advantages include higher stiffness and higher strength, Minnichelli added.

The advanced continuous fiber thermoplastic composites, paired with predictive simulation software and other technology, allow manufacturers to place the fibers going exactly in the direction needed for the highest performance and most benefit, Lyons said.

“As a result, these higher cost, higher performance materials can be used only exactly where you need them,” he said.

Costs are higher and manufacturing is more complex, Lyons said, but the value and benefits to this approach can offset those challenges.

“Some people may think of composites only as these extremely high tech continuous fiber components, which BASF does sell,” Minnichelli said. “Many of the applications that we’re talking about today are injection molded short glass fiber reinforced or short carbon fiber reinforced using a fairly standard injection molding process the industry has been using for years and years. We’re introducing newer materials that have either different loadings for fiberglass or new loadings of carbon fiber materials that bring enhanced properties to the parts that emerge from the mold.”

Looking back and ahead

Chopped fiberglass thermoplastic composites entered the market in the 1970s, about 10 years after thermoset composites began to be used in military and aerospace applications. At that point, thermosets already were making their way to consumer products.

But the less mature thermoplastics sector faltered in the 1990s as the military buildup slowed. Major companies that had worked on the technology exited the supply chain and licensed the tech to smaller companies, Buck said.

“That left the small companies to carry the load and left the industry in disarray,” he said. “A company like Boeing was not going to put all their eggs into a small company to make all the parts it needed. It took longer for the materials and capabilities to come around again. It needed growth in the supply chain.”

That supply chain growth is happening now.

BASF continues to investigate opportunities, especially in the automotive industry, Minnichelli said. “We continue to chase the more challenging opportunities around vehicles, for example. We are continuously seeking to develop higher strength, higher stiffness, more heat-resistant materials with thermoplastic composites. We believe there are further opportunities to take weight out of vehicles by replacing more metals.”

With the wave of commercial aircraft development in 2010, the aerospace industry and others started looking at new ideas to reduce weight and cost in manufacturing, Kneath said. That’s when Tri-Mack began researching new materials and manufacturing technologies. The company considered both additive manufacturing (AM) and advanced thermoplastics.

“We wanted to bring on a new technology that was cutting edge,” he said. Although AM continues to advance, Tri-Mack customers responded more favorably to advanced thermoplastics.

“Thermoplastic composites yielded a performance of 10 times traditional injection molded parts,” Kneath said.

Around the same time, Barrday also started looking at advanced thermoplastics. In 2014, Buck stepped down as CEO to lead the company’s entry into the new material.

“Two things are critical in generating the excitement and renaissance of thermoplastic composites in the industry,” he said. “One is improvements in the format, better pre-preg with pre-preg companies like us. The second is the growth and maturity of the parts-making industry. There are many new technologies and processes coming on line that should help drive the industry for many years to come.”

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