Hexcel launches conductive new HexPEKK polymer for 3D printing “flight ready” aerospace parts 

Advanced composite materials company Hexcel has launched a new electrically-conductive polymer-based carbon fiber composite for 3D printing. 

The firm’s new thermoplastic, HexPEKK EM, has been custom-made to meet the static electricity management, electromagnetic (EM) shielding, and radiation absorption needs of advanced aircraft applications. By integrating EM qualities directly into 3D printed parts, Hexcel’s material could enable users to cut out costly post-processing steps, and deliver “flight-ready” components from the outset. 

“The introduction of this advanced additive manufacturing material will enable the fabrication of extremely complex aerostructures with unparalleled structural and electrical functionality,” said Lawrence Varholak, Vice President of Additive Manufacturing at Hexcel. “It significantly reduces weight and cost while providing unlimited design flexibility.”

Hexcel is aiming to address a wider variety of aerospace applications with its new HexPEKK EM 3D printing material. Photo via Boeing.
Hexcel is aiming to address a wider variety of aerospace applications with its new HexPEKK EM 3D printing material. Photo via Boeing.

Hexcel’s growing portfolio of 3D printing materials

Having been founded in 1948, Hexcel is an established producer of materials, not just for the 3D printing industry, but the wider industrial manufacturing sector as well. In addition to its product portfolio, the company has vested interests in a variety of sectors, including the flight, energy generation and transportation industries. 

Hexcel’s current product lineup includes a range of carbon fibers, fabrics, adhesives and tooling materials, but those within 3D printing will most likely recognise its proprietary line of HexPEKK thermoplastics. The polymer range has been optimized for fabricating aerospace parts, and has even fulfilled the interior aircraft smoke and toxicity requirements (UL VO, OHS) for end-use within the industry. 

Hexcel’s additive aerospace focus can be traced back to 2016, when it opened a new research center in Duxford, UK, with the aim of developing new composite materials for the aviation and industrial markets. A year later, the firm went a step further, and acquired Oxford Performance Materials (OPM), a known producer of high-performance thermoplastic and carbon fiber-reinforced 3D printed parts.

After the acquisition, Scott DeFelice, CEO of OPM, said that its focus “remained on the applications of PEKK” and that the firm had “some exciting new materials in development.” Hexcel subsequently reaffirmed its commitment to developing new PEKK aviation materials, by gaining 3D printed part approval from multinational aeronautical corporation Boeing

The accreditation was awarded directly to Hexcel’s HexPEKK polymers, and this allowed them to be used within the fabrication of brackets, environmental control system ducts, and castings. Following the launch of the latest edition of HexPEKK, the company is now aiming to address an even broader set of applications within the aviation sector. 

Hexcel’s existing HexPEKK material has already been used to create a range of aerospace components (pictured). Image via Hexcel.

HexPEKK EM’s lofty aerospace credentials 

At present, non-EM enabled printing materials require a conductive coating to be applied, in order for them to possess the required qualities for use within the aerospace industry. Conductivity is essential within aviation applications, as it enables parts to effectively manage electromagnetic interference and absorb radiation. 

Hexcel’s new PEKK material has integrated EM properties that forgo the need for such expensive and time-consuming post-processing tasks, which potentially makes it well-suited to printing a range of aerospace parts. The polymer was developed using the firm’s industry-qualified HexAM process, meaning that it has already demonstrated a high-level of performance in terms of the sustainability, operating temperature, and chemical resistance.

“The management of static electricity dissipation, electromagnetic interference, and radiation absorption is extremely important in the design of all air vehicles.”

The company’s self-proclaimed “industry-leading” material is targeted at producing components for end-use within commercial airplanes, military aircraft, helicopters and UAVs. According to Hexcel, this makes HexPEKK EM ideal for reducing the weight and cost of relevant parts such as air inlets, electronic enclosures, and cockpit structures. 

What’s more, the inherent design flexibility of 3D printing could encourage similar aviation objects to be re-designed in a more cost and performance-efficient way. Moving forwards, the firm has committed to continue developing its patented HexAM process, to “fundamentally improve the way the world’s aircraft components are manufactured.”

PEKK’s role in additive manufacturing 

Polyetherketone (or PEKK’s) thermal resistance features have made it popular within the aerospace sector, but researchers have found increasingly experimental ways of using its antibacterial qualities as well. 

3D printer manufacturer EOS worked with Boeing to develop its own carbon-fiber reinforced PEKK material in April 2018. The polymer was designed to meet the challenging UV resistance, flame retardancy and federal aviation regulations surrounding the aerospace sector. 

Elsewhere, researchers at OPM and McGill University, demonstrated the material’s anti-bacterial qualities by creating 3D printed PEKK implants. OPM’s transplants enabled bone cartilage repair and reportedly showed strong evidence of new bone formation.

A team from Northeastern University, meanwhile, have built on OPM’s use of PEKK materials, by developing 3D printed anti-infection orthopedic devices. Inspired by the naturally repellent surface of cicada-wings, the team’s finely-tuned “nanopillars,” were reportedly comparable to industry-standard PEEK implants. 

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Featured image shows a Boeing 777X taking off. Hexcel’s aerospace 3D printing materials were added to Boeing’s approved supplier list last year. Photo via Boeing.