Thermoplastic composites: Past the tipping point?

The manufacturing world watched a decade ago as automatically placed thermoset composite tapes replaced aluminum in commercial airframes and made composites a household word in markets around the world. Has the time come for thermoplastic composite tapes to make a similar impact?

The manufacturing world watched a decade ago as composites gained supremacy over aluminum in the production of commercial aircraft. Fiber-reinforced thermoset tapes, placed automatically on massive tools and cured in even larger autoclaves under significant pressure and heat, formed the wing and fuselage structures of The Boeing Co.’s (Chicago, IL, US) 787 and the Airbus (Toulouse, France) A350 XWB. These carbon fiber/epoxy primary structures resulted in genuinely revolutionary midsize, twin-aisle passenger aircraft.

And these events made composites, particularly the carbon fiber-reinforced plastic (CFRP) variety, a household word. And they signaled the industry’s first big steps toward what has since been an irreversible advance toward industrialization. As a result, CFRP has grow dramatically in higher volume, nonaerospace markets including oil and gas, automotive, industrial and consumer applications.

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Thermoset composites processing has come a long way over the past ten years. Snap-cure resins (see CW’s report on sub-1-minute-cure epoxies titled “Fast and Faster: Rapid-cure resins drive down cycle times”), robotic tape placement with onboard, real-time inspection and less energy-intensive and time-consuming out-of-autoclave cure cycles have given a variety of manufacturers viable options for low- to medium-volume series production.

Meanwhile, thermoplastic composites (TPCs) have been developed for over two decades now, aimed at both aircraft and nonaerospace applications. Although thermoplastics, like thermosets, must be thoroughly consolidated to achieve required part surface quality and acceptable void content (<2% in aerospace), they do not crosslink, and therefore, offer abbreviated cycle times. They also are inherently fatigue-resistant (addressing a key concern for aircraft manufacturers) and provide toughness, durability and recyclability.

It makes sense, then, that automated placement, unidirectional (UD) tape and thermoplastics have recently converged. But the momentum it has gained is a bit breathtaking: In CW’s 2017 print article and Blog series on automated preforming, as well as its two-part 2018 series on in-situ consolidation of TPCs, the potential for placement, consolidation and real-time inspection of thermoplastic composite tapes in a single step, without subsequent application of heat and pressure via autoclave or other means, is within reach.

The savings in time, capital and operating expenses that these TPC developments represent is impossible to ignore. Indeed, for its recent TPC coverage, CW has been in contact with no less than 18 companies that offer automated tape placement technology: Accudyne, AFPT, Automated Dynamics, Automation Steeg and Hoffmeyer, Broetje, Cevotec, Composite Alliance Corp., Compositence, Coriolis Composites, Dieffenbacher, Fill, Mikrosam, MTorres, Novotech, Tri-Mack Plastics, Van Wees UD and Crossply Technology, Voith Composites and the Quilted Stratum Process (QSP) at Cetim. This list is by no means exhaustive. Others are doing the same and still others are focused on overmolding of tailored tape blanks, which is a purely TPC process. (Discover more about this developing technology at CW’s upcoming conference “Composites Overmolding: A 1-minute cycle time initiative,” June 13-14, 2018.) Notably, a once fragmented supply chain is now coming together into a more integrated, streamlined whole, offering truly industrial capacity in both aerospace and nonaerospace markets.

Two key examples of this include the development of flexible, fully automated production lines by partners Airborne (The Hague, The Netherlands), Siemens (Plano, TX, US) and SABIC (Bergen op Zoom, The Netherlands), which will use the latter’s UDMAX thermoplastic composite tapes to produce hundreds of thousands to millions of parts per year at radically lower cost. “We are building an actual production line, which will produce parts later this year.” says SABIC business leader for composites Gino Francato. Target markets include aerospace, commercial vehicles (trucks) and pipes, with the first applications slated for automotive and consumer electronics.

Meanwhile, Covestro (Leverkeusen, Germany) has partnered with the world’s No. 1 appliance supplier Haier (Qingdao, China) to use continuous fiber-reinforced thermoplastic (CFRTP) composites in the housing of the high-end Casarte line of “smart” air conditioners. Covestro’s unidirectional polycarbonate tape solution provides not only lightweight and durability, but also eliminates post-forming finishing processes like sandblasting, brushing and anodizing required by metals.

Exactly one year ago, CW sat down with Tim Herr, aerospace director at Victrex (Thornton-Cleveleys, UK) and Tom Kneath, director of sales and marketing for Tri-Mack Plastics Mfg. Corp. (Bristol, RI, US) to discuss the formation of TxV Aero Composites. “Thermoplastic composites has been ‘the next big thing’ for 30 years,” said Herr. The drive to abbreviate part production cycles has come full-circle. “More recently,” he pointed out, “the commercial aerospace market has signaled that thermoplastic composites are the material of the future that will enable them to achieve necessary cost reduction via highly automated production systems. Manufacturers have made it clear to us that their throughput rate must be higher than it is today.”

And it is no mere coincidence that Hexcel (Stamford, CT, US), the principal supplier of carbon fiber to Airbus for its commercial aircaft, partnered with thermoplastics source Arkema (Columbes, France) a mere two weeks after Toray Industries (Tokyo, Japan), the carbon fiber source for Boeing, announced its impending acquisition of multinational thermoplastics giant TenCate Advanced Composites (Morgan Hill, CA, US and Nijverdal, The Netherlands). This follows earlier 2018 press releases from Daher (Marseille, France) and LMI Aerospace (St. Louis, MO, US) touting multi-year contracts with Boeing for thermoplastic composite parts.

That long-predicted future opportunity for TPCs seems to be materializing now. And perhaps the optimistic projections are actually justified, with the swell generated by automotive and other nonaerospace markets coinciding with the wave beginning to crest in commercial aircraft. Should be an interesting ride.

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