JEC World 2019 preview: Hexcel

Hexcel (Stamford, Conn., U.S.) is featuring range of composite innovations for customer applications in aerospace, automotive, energy and marine markets.

Aerospace

Hexcel’s HiTape and HiMax dry carbon reinforcements were developed to complement a new generation of HiFlow resin systems, producing high-quality aerospace structures using the resin infusion process. HiTape was developed for the automated layup of preforms; HiMax is a range of optimized non-crimp fabrics (NCF). Both products incorporate a toughening veil to enhance mechanical properties, meeting the structural requirements for aerospace parts.

Visitors to JEC can see an Integrated Wing Panel demonstrator and an I-beam, both made with HiTape reinforcements, and an Opticoms rib made with HiMax NCF. The Opticoms rib and I Beam were both manufactured using C-RTM (Compression Resin Transfer Molding). They were injected with Hexcel’s RTM6 resin in a process that took less than 5 minutes. The total manufacturing cycle for both parts was just 4.5 hours.

Also among the aerospace exhibits, Hexcel is featuring a composite petal for a satellite antenna, manufactured by Thales Alenia Space Italia. The petal is part of a set of 24 deployable structural elements that form the large-area reflector assembly used on board low Earth orbit (LEO) observation satellites. Thales Alenia Space Italia selected Hexcel’s HexPly M18 prepreg for this application.

Another Hexcel prepreg application on show is a “zero” frame, manufactured by Aerofonctions for the engine area of Daher’s TBM 910/930 single-engine turboprop aircraft. Hexcel’s HexPly M56 prepreg was selected by Daher for the “zero” frame – a product developed for out-of-autoclave applications that is said to provide the same high quality and performance as autoclave-cured prepregs, from a simple vacuum bag cure in an oven.

Hexcel is introducing two new carbon fibers to its portfolio. HexTow HM50 combines high modulus and high tensile strength, making it ideal for commercial and defense aircraft and engines. HexTow 85 was developed specifically to replace rayon-based carbon fiber for ablative applications.

HexTow carbon fiber, says Hexcel, provides good bonding interfacial properties with thermoplastic matrices and is the best-performing fiber for 3D printing applications. Additive manufacturing is another area of expertise for Hexcel, using PEKK ultra-high performance polymers and HexAM technology to manufacture carbon fiber-reinforced 3D printed parts. This process provides a weight-saving solution for intricate parts in highly demanding aerospace, satellite and defense applications. HexPEKK structures are said to offer significant weight, cost and time-to-market reductions, replacing traditional cast or machined metallic parts with a new technology.

Hexcel also is emphasizing its engineered core solutions, supplied from facilities in the U.S., Belgium and a newly opened Casablanca plant in Morocco. Hexcel’s engineered core capabilities enable highly contoured parts with precision profiling to be produced to customer specifications. An example of such a part will be on display at JEC: Made from Aluminum FlexCore, the part is CNC machined on both sides and formed and stabilized with peel ply and flyaway layers of stabilization. HexShieldTM honeycomb is designed to provide high-temperature resistance in aircraft engine nacelles. By inserting a thermally resistant material into honeycomb cells, Hexcel provides a core product with heat-shielding capabilities that allow for potential material re-use after a fire event.

Hexcel’s Acousti-Cap broadband noise-reducing honeycomb is designed to improve acoustic absorption in aircraft engine nacelles. The acoustic treatment may be positioned at a consistent depth and resistance within the core, or can be placed in a pattern of varying depths and/or resistances, offering an acoustic liner that is tuned to engine operating conditions. Hexcel says these technologies have been tested at NASA on a full engine test rig and meet all 16 design conditions without trade-offs.

HexBond, Hexcel’s range of high-performance adhesives, has expanded considerably following the company’s acquisition of Structil. The company has now decided to unite the range by marketing all of its adhesive products using HexBond branding. The range of HexBond structural film adhesives, foaming adhesive films, paste adhesives, liquid shims, epoxy fillets and chromium-free liquid primers is designed for a range of applications in combination with Hexcel’s prepreg and honeycomb products.

Automotive

Hexcel’s carbon prepreg patch technology provides a way to locally stiffen and reinforce metal parts, providing noise and vibration management functionality. HexPly prepreg patches consist of unidirectional carbon fiber impregnated with a fast-curing epoxy matrix that has self-adhesive properties, enabling it to bond to metal in a highly efficient one-step process. These properties are demonstrated in an 18.5-kilogram aluminum subframe (50% lighter than steel equivalents) that was reinforced with 500 grams of HexPly prepreg and tested by Saint Jean Industries. The part demonstrates a significant reduction in noise, vibration and harshness (NVH). Other benefits include lower production costs, energy savings, increased driver comfort, production flexibility and part-count reduction. This technology is a finalist in the JEC Innovation Awards 2019 in the Automotive Applications category.

HexPly prepreg patch technology was also applied to a hybrid side sill demonstrator developed with Volkswagen and Dresden University to address future crash test requirements, specifically for electric cars. Combining fiber-reinforced plastic (FRP) with metal, the hybrid construction allows for optimum performance including weight savings, enhanced safety, increased energy absorption, battery protection in a crash situation and production flexibility.

Hexcel also is featuring a lightweight CFRP transmission crossmember produced from HexMC-i 2000 molding compound. The transmission crossmember was developed in partnership with the Institute of Polymer Product Engineering (at Linz University), Engel and Alpex. As the part connects the chassis together and supports the transmission, it has to be stiff and strong, resisting fatigue and corrosion. Hexcel’s HexMC-i 2000 was selected as the best-performing molding compound on the market, curing in as little as 2 minutes to produce lightweight, strong and stiff parts.

To produce the transmission crossmember, HexMC-i 2000 preforms are laid up in Alpex molds and compression molded in a v-duo press designed for the application by Engel. Ribs, aluminum inserts and other functions can be molded into the part using the single-stage process, reducing component count. Any offcuts from the preforms can be interleaved between the plies of material to provide additional reinforcement in key areas, meaning that the process generates no waste.

Other automotive products include a composite leaf spring manufactured by ZF using HexPly M901 prepreg. In contrast to steel leaf springs, composite versions offer many advantages including weight savings of up to 70%, high corrosion resistance, optimized system integration and superior performance. HexPly M901 prepreg reduces the cure cycle to less than 15 minutes and provides 15% greater mechanical performance, with enhanced fatigue properties. It also operates at high temperatures, providing a T_g of up to 200°C following a post cure.

Marine

Hexcel has a range of products aimed at racing yacht and luxury boatbuilders that include America’s Cup-, IMOCA class- and DNV GL-approved prepregs, woven reinforcements and multiaxial fabrics for hull and deck structures, masts and appendages.

Hexcel is displaying an IMOCA yacht mast manufactured by Lorima using HexPly high-modulus and high-strength carbon fiber prepreg from Hexcel Vert-Le-Petit. Lorima is the exclusive official supplier of masts for IMOCA 60 class racing boats. Hexcel’s HexTow IM8 is being used by spar and rigging manufacturer Future Fibres to manufacture their AEROrazr solid carbon fiber rigging for all the teams in the 36th America’s Cup.

Hexcel’s HiMax DPA (dot pattern adhesive) reinforcements are non-crimp fabrics supplied pre-tacked, allowing multiple fabrics to be laid-up more easily in preparation for resin infusion. Providing a consistent level of adhesion, they reportedly allow a faster and more consistent resin flow, as well as eliminate the use of spray adhesive.

Wind Energy

Hexcel has developed a range of HexPly surface finishing prepregs and semipregs for wind turbine blades and marine applications. Providing a tough, durable and ready-to-paint surface without using in-mold coats, these products are said to shorten the manufacturing cycle and reduce material costs. HexPly XF2(P) prepreg is optimized for wind blades and has a ready-to-paint surface, straight from the mold.

Polyspeed pultruded carbon fiber laminates were developed for load-carrying elements in a wind blade structure and are manufactured with a polyurethane matrix that is said to provide good stiffness and durability performance.

HiMax non-crimp fabrics using E-glass, high-modulus glass and carbon fibers are also available in a range of unidirectional, biaxial and triaxial constructions. HiMax fabrics have applications throughout the turbine, from the stitched carbon fiber UDs used in the main structural elements, to glass fabrics and hybrids for blade shells and nacelles. There are also specialist applications such as lightweight fabrics for heated leading edge de-icing zones.