The ultimate design opportunity arrives!

AMMay18Features - hexcel3
AMMay18Features - hexcel3

Hexcel took to the JEC World event to display an increasing array of additive manufacturing product innovations for a host of aerospace component-related applications. Mike Richardson reports.


Among the aerospace promotions on show at Hexcel’s JEC World, Paris booth were carbon-reinforced additive manufactured parts made from its HexAM technology (AM) using PEKK ultra-high-performance polymers.

Hexcel acquired this technology from Oxford Performance Materials (OPM) in December 2017 to provide weight-saving solutions for intricate parts in demanding aerospace, satellite and defence 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.

With the acquisition of OPM (now renamed Hexcel Hartford and based in Connecticut) rolled up into its engineered products business, Hexcel now offers 3D carbon fibre-filled PEKK thermoplastic AM parts. The company believes there are tremendous advantages with respect to tooling, cycle time, and designing and manufacturing very complex parts in a single shot, single application. Hexcel already has materials qualified and flying.

“Back in the 1980s, thermoplastic materials were considered within the technology field for developments of prepreg materials for use in aerospace structures,” begins Hexcel’s senior vice-president and CTO, Paul Mackenzie. “We are seeing greater use and adoption of thermoplastic technology, and Hexcel’s acquisition of OPM is a great testament to the capability they have built up and the technology available.

“Typically, we are using our proprietary matrix based on PEKK, but we add carbon fibre materials to it in order to get an optimum product performance for use in the selective laser sintering (SLS) process. The real issue and capability here is in replacing aluminium machined and titanium machined parts, not only in terms of weight savings, but also ultimately in terms of the actual capability to manufacture parts at a lower cost. Additive layer manufacturing (ALM) is coming of age and is being closely looked at for the mass production of specific parts in certain aerospace applications.

The HexAM effect

Hexcel’s trade name here will be HexAM and comprises two particular products: its already aerospace qualified HexPEKK 100 and HexPEKK 150. Mackenzie says there are many comparisons with fused deposition modelling (FDM), a technology that has been around longer in terms of ALM.

Paul Mackenzie, Hexcel senior vice-president and CTO

“The machinery is less capital-intensive, but the parts made using FDM tend to be less complicated, whereas if you want to take the more complicated path, ALM and SLS are really the only areas to opt for. Hexcel’s HexPEKK 150 provides a better overall performance in design allowables, compared with ULTEM, which is made using the FDM process.

“Hexcel is in the first stages of its journey with additive manufacturing, but the opportunities to replace cast aluminium and titanium are very real, and we will be progressive in pursuing all these opportunities, not only in replacing traditional metallic materials – but also in looking to provide innovation in other thermoplastic areas via additive manufacturing as a manufacturing process.

Another technology area of great interest concerns infusion technology. Hexcel is part of a UK Aerospace Technology Institute (ATI) and UK Government match-funded project called Multi Axial Infused Materials (MAXIM), with the aim of developing multiaxial non-crimp fibres (NCF) in terms of infusion products. Over 2m in width, Hexcel has developed this material and is in the process of installing equipment at its Leicester facility, whilst the resin technology will be manufactured at its Duxford facility.

“The opportunity for Hexcel to provide materials for infusion: the resin technology, the NCF and our HiTape and HiMax products - which provide extra mechanical performance - enables the entire infusion envelope to be competitive with prepreg in terms of the overall mechanical performance. We are very pleased to be associated with the UK Government for funding on this scheme.

“Innovation is one of our core areas and values that we take extremely seriously and we have invested greatly in our innovation centres. We are now building a new centre in Les Avenières, France, due for completion towards the end of this year and opening in 2019. Les Avenières’ capability will be associated with infusion, out-of-autoclave technology, HiMax and HiTape, and ultimately as we expand our additive manufacturing capabilities, we’ll look to include it within the Les Avenières site too, making it a centre of excellence in Europe for additive manufacturing.”

Faster, lighter, stronger

I’m interested to learn what advantages Hexcel is seeing in the speed of using AM as opposed to traditional manufacturing. According to Mackenzie, Hexcel is seeing faster manufacturing improvements.

“It’s about the complexity of the part,” he concludes. “We want to make complex parts that take time in terms of CNC routing machining in order to get to the complex structures that they want. It is also very much about weight saving too: these additive manufactured parts will be much lighter and faster to produce. The industry realisation is certainly there, and we are doing increasingly more work to demonstrate this and garnering more interest in the technology as industry gradually sees the applicability and value in it. It’s in its early stages, but we are one of the first companies to be qualified in aerospace applications, so it’s a testament to the capability and technology.”

The ultimate, optimum design opportunity has arrived with additive manufactured parts

Mackenzie notes that the real differentiator of additive manufacturing is that certain components can be manufactured via this process that could never be considered through the use of conventional means.

“The ultimate, optimum design opportunity has arrived with additive manufactured parts. In many cases, we can additively manufacture to near net shape,” he concludes. “We’re thrilled with the technology and we are expanding our portfolio to cover the high, intermediate and even the lower end product offerings, because not every application will require the most premium product type. As the scale of adoption increases, cost will clearly come down and expand into more opportunities.

“Additive manufacturing is ideal for producing lightweight components but it will never replace every part because it just isn’t economically viable for basic parts that can be easily manufactured. However, for aerospace parts with complex geometric features where space and weight are critical, design engineers want the freedom to optimise their designs. The breadth of Hexcel’s product portfolio is truly unique within this industry and no-one has our capability in respect of vertical integration: from the PAN precursor to the manufacture of high strength intermediate and high modulus carbon fibre materials to satisfy applications in both the aerospace and industrial sectors.”



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