Process innovation now the focus of the composites industry

The JEC Show in Paris has become the annual must go to event for composite manufacturers. The talk was once all about the possibilities but this year that turned firmly on the practicalities. While the composites industry has always been inextricably linked to lightweight parts, this year’s show was keen to highlight that high volume composite parts aren’t a pipe dream, but a production ready reality.

Many firms that were once on the peripheries of the composite industry are now at its forefront, after investing in their own product development, building relationships and are rolling out real solutions.

This is the case for Henkel. Five years ago the company was best known as a developer of its adhesives staple Loctite. However, fast forward to 2016 and it has placed itself at the sharp end of automotive R&D. Like many, the catalyst has been European automotive emissions reduction regulations that are forcing most major automotive OEMs to look at lightweight composite materials. This has opened up the composites market well beyond high end specialists users like aerospace, and attracted to work out how to meet the needs of other industries.

Henkel has significant legacy in chemical engineering, meaning the advent of composite resins and adhesives to suit have given it fresh ground for product development and subsequent innovation.

“We have found that our customers can have trouble with the chemistry required,” says Frank Kerstan, global program manager for automotive composites at Henkel. “We have got the chemical and material knowledge and they expect us to do this kind of development.

“It is highly complex to develop epoxy resins that cure quickly, to bond different materials, and develop those processes. So we have found we have been able to work with OEMs and provide that expertise.”

The automotive industry has been much slower to adopt composites than those in civil aerospace. The high value, low volume nature of aircraft make composites a natural choice. However, for automotive engineers – especially those in the mainstream – the nature of the operation could not be more different, with engineers demanding low value cheaper part, made in high volumes.

Making it work

Automotive OEMs were quick to point to composites when the emission regulations were announced. It was the obvious choice to take weight out of vehicle structures. But while the potential benefits are known, making it a cost effect process suitable for high-volume production has proved considerably more challenging. Autoclaves are most certainly out with ‘snap cure’ or ‘fast cure’ definite buzzwords on the JEC show floor in 2016.

It was for these reasons that Henkel has set up and recently opened its Composites Lab in Heidelberg, Germany, to not only develop resins and test them, but also to work with customers to develop finished parts and components.

“We’re developing the process knowhow,” says Kerstan. “And within that is getting the costs down, making sure we can scale up the volumes, but still ensure the quality expected. We want to show that our resin is easy curing and automatable.”

The Composites Lab has helped to refine the resin and adhesive options for a recent hybrid composite metal component for the automotive industry. It uses a Loctite MAX 2, a two-component polyurethane composite matrix resin system, enabling automotive composites specialist Benteler-SGL to develop an innovative, glass-fibre-reinforced leaf spring. The composite spring is manufactured using Resin Transfer Moulding (RTM) and is designed for a production output of over 100,000 parts a year. Such is the success of the innovation, Volvo is now using it on its latest XC90, S90 and V90.

“We could see 500,000 of these parts made per year,” says Kerstan. “It has great mechanical performance and toughness, and we can inject the resin quickly at low viscosity which enables us to get the cycle time down.”

Though the leaf spring suspension principle is perhaps viewed by many as antiquated, it does seem to be making a return as a composite component. Indeed, Ford also uses the set up on its F-150 as does Corvette. Though it is much rarer to see a European manufacturer adopting it, Henkel says Volvo could be the first of many to return to the technology in an effort to shed weight.

Not just about lightweighting

While the focus for composites has traditionally been about lightweighting, 2016 saw a marked shift in how many material developers and users are viewing the material. Plastics giant Solvay was keen to explain that it has recently had its TegraCore (polyphenylsulfone) PPSU foam qualified for flight by Airbus. The material can be used on its own or with skins, and has good resistance to damage, fire and chemicals.

Solvay is making the pitch for its foams against aluminium honeycomb that is popular in the aerospace industry, both on aircraft and spacecraft.

“Most of the core technology that is out there is based on old technology,” says Armin Klesing, business development manager of aerospace & composites, Solvay Specialty Polymers. “It was developed 30 years ago when the aircraft industry was building one aeroplane a month. Today the big OEMs are heading for 60 aircraft per month.”

Solvay compare its TegraCore as a technology that is set up to service two aircraft a day, as opposed to other sandwich materials that were developed when volumes were much lower.

“It’s for higher volume manufacturing and applications,” continues Klesing. “The key is that TegraCore is highly automatable. It means we can help OEMs build more aircraft quicker, and the aircraft costs less to produce.”

Solvay also claim that TegraCore has much better damage resistance than other honeycomb or core options on the market. But what about the weight?

“If you want to say its density is always lower, that is not what our customers are asking for,” says Klesing. “Nobody is asking us for lower density. They are asking for lower costs to make parts, longer maintenance cycles, better damage resistance and more automation. The key thing is to allow the industry to make more aeroplanes, quicker.

“They always want low weight, of course, but today that is not the key driver. If I have a part that is lower weight, but it does not allow me to make parts quicker it is not of real value. Does the industry want heavier parts? Of course not. I don’t go to my customers and say the density of my parts is 5% lower, as they don’t care. They say, can you help me make more aeroplanes, and get them out of the door.”

While the density of TegraCore is thought to be slightly higher than aluminium honeycomb, Solvay is confident that its ability to offer Airbus and Boeing a throughput advantage will be a key selling point for the material. Indeed, Airbus is to use the material on its A350 XWB it began delivering last year.

Green innovation

While the low density of composites are generally seen as an environmental step in the right direction, as they reduce emissions of a vehicle in use, there production and disposal is not perceived in the same light. This has led to French based Sicomin developing a bio-based epoxy resin, GreenPoxy.

With its bio-based carbon content ranging from 28% to 51%, the highest on the market tested in accordance with ASTM D6866, Sicomin claims to offer the largest choice of bio-epoxy systems that can be used for hand-laminating, infusion, pultrusion and filament winding, as well as HP-RTM.

The use of GreenPoxy has proven highly popular in the sport and leisure industry for its clarity and uncompromising mechanical performances, but is it something that could be taken on by other major engineering sectors?

Marc Denjean, export manager at Sicomin explains: “We are seeing a bigger acceleration this year, which is related to the maturity of the product we can offer. Until now, the price was far too high. So we reduced it, by putting more bio-based resins in more formulations without really mentioning or marketing the fact, as that wasn’t a driver for our customers. But that has helped volumes to grow which has brought prices down.”

Sicomin is gradually offering a bio-based alternative to customers for resins that equivalent in terms of look, clarity and mechanical properties. “If you do a blind test, you can’t tell any difference,” says Denjean.

Bio resins have been known to be two to three times more expensive, but this has now dropped to ‘just a few percent’ says the company. So this is allowing bigger customers to switch, as larger quantities have become available, that do not compromise any of the end properties compared to a 100% oil based alternative.

Sicomin state they will not compromise mechanical performance or clarity, and so opt for a blend of oil based and bio based resin.

“There is no room for compromise in performance,” says Denjean. “Clarity, reactivity, everything must be normal and standard and that is a high expectation. Today we are 51% maximum at equal performance. We also have 35%, 28% and a few others in the range. We know how to do more, 70% or more, but we lose on the colour and performance. But we are working and want to get there with 100% bio based with the full performance of an epoxy product.”

Justin Cunningham

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How do I keep up - within a reasonable amount of effort - with the new materials, cost s and availability?

Comment Fred Jiran, 19/06/2016

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