CompositesWorld
Issue link: https://cw.epubxp.com/i/517026
JUNE 2015 38 CompositesWorld FEATURE / REINFORCED THERMOPLASTICS "We've been perfecting this process for several years, and are currently involved in qualifying it for Airbus," he says, to show equivalency with flmed and solvent-based prepregs. Te powder- coater can rapidly dispense any thermoplastic resin onto a fabric, which then passes through heated rollers and an oven to melt and crystallize the polymer as required. "We can achieve very tight thickness tolerances," adds Kok, and explains that if thicker products are required, the material can be sent through the machine twice for two coats of resin. TenCate's well-known CETEX thermoplastic sheet is made in three, large, heated compression presses that operate around the clock. Workers lay up thermoplastic prepreg material to form the 3.6m by 1.2m sheets, in any fber architecture from 1 to 24 plies thick, to customer specs. PPS is the most common matrix, says Kok, who explains that the layups are moved to the press, heated and consolidated in a heating, compression and cooling process that depends on sheet thick- ness and resin type, and desired resin crystal- linity. Te pre-consolidated, stif sheet product is virtually void- free — all CETEX sheets undergo a C-scan inspection to verify quality and thickness before customer shipment. "We're continuously working to develop new products, with higher performance. For example, PEI has good fre/smoke/ toxicity properties, but it doesn't stand up well to hydraulic fuid, so PPS or PEEK is a better choice for wet applications," concludes Kok. "An example of a recent product development is carbon fabric/PEI prepreg used as an air inlet liner in the engines on several Airbus aircraft." He adds, "Our participation in the TPRC allows us to stay abreast of advances in thermoplastics, and to conduct our own product research projects there — while allowing other partners to familiarize themselves with our products." Carbon fiber thermoplastics a priority Although traditional fberglass weaving has been contracted out to another supplier, TPRC member TenCate's Nijverdal plant continues to weave carbon-fber fabrics, which are eventually prepregged with thermoplastic resin at the facility to become CETEX thermoplastic sheet products, in one of three large presses. Source (both photos) | TenCate/© TenCate Boogert, along with manager of engineering Winand Kok and sector sales manager Aerospace EMEA Marlie Koekenberg, demonstrated during CW's recent visit the evolutionary changes that have occurred in TenCate's business, starting with its legacy weaving rooms that feature English-style sawtooth glazed roofs that kept the fabrics from direct sun while allowing shadow-free light — the best light for evaluation of textile quality. Many auto- mated looms, until recently, produced commodity fberglass and aramid fabrics. Tese are now made under contract by Hexcel (Stamford, CT, US, and Les Aveniers, France), explains Kok. Five- harness, satin-weave carbon fabrics, typically 125-cm wide, will continue to be made in-house on high-speed, automated Lindauer DORNIER (Lindau, Germany) rapier looms, using 3K carbon fber tow supplied by Toray Carbon Fibers Europe (Paris, France). To convert its technical carbon textiles to thermoplastic composites, TenCate uses several processes and works with several polymer suppliers, including Victrex Plc (Cleveleys, Lancashire, UK), Arkema (Colombes, France) and Celanese Corp. (Irving, TX, US, and Oberhausen, Germany). For the fberglass/polyphenylene sulfde (PPS) material used by Fokker Aerostructures to form the J-nose fxed leading edge on the Airbus A380 aircraft wings, a PPS flm is applied to both sides of an eight-harness, satin-weave (re-sized) fberglass fabric in a heated laminating process, to form what Kok calls a semi-preg product. For semi-preg materials typically used in aircraft fooring and interiors, woven carbon, glass or aramid fbers are dip-coated with polyetherimide (PEI) in a solvent-coating process. But semi-preg also can be made in a powder-coating process that, Kok explains, eliminates the cost of forming thermoplastic laminating flms. Te process uses machinery designed by TenCate in-house. TRPC is a knowledge institute where members all along the value chain help to shape the research roadmap.