Engineering foams look set to make a comeback

Slightly odd looking and – well – quirky, you can see that a recent partnership between Toyota and French design house, Studio Massaud, was about challenging convention. The appearance ME.WE concept car certainly does that by using body panels made of expanded foam known as Arpro.

The vehicle was designed with minimal weight in mind and realised that steel body panels would be just too heavy. Other materials such as aluminium, composites, plastic all offered disadvantages from cost to production, yet Arpro, seemed to tick all the boxes.

There is no doubt that the concept car is aimed to evaluate the potential of using expanded foam type products as body panels and visual parts, and to quantify any weight or performance benefit. And once you get past the initial gasp, it actually makes a lot of sense.

Arpro, manufactured by JSP, has been used for many automotive applications from bumpers to head restraints. It has been increasingly finding its way in to the average vehicle in the last few years as manufacturers have sought to reduce weight, yet increase safety.

The materials is both lightweight and has very good energy absorption. It's unique combination of physical properties, allowing it to be compressed and absorb significant energy without failing, not just once but on multiple occasions.

This has made it an attractive option for many passive safety products such as side impact energy absorbers in door panels, head restraints and seat cores, seating and knee protection. Its strength to weight ratio has also seen it used to lighten boot liners, load floors and console components.

However, to date all of these applications have been hidden away from sight. Until now, that is. The ME.WE aims to offer an 'attractive' yet practical vehicle that answers some of the current economic and environmental challenges. You are either going to like or hate it... but don't be surprised if it grows on you.

The ME.WE features extensive amounts of Arpro internally and externally, to offer five varied key benefits. The first, and perhaps most obvious is its lightweight. Comparing the ME.WE with a traditional car of the same size, the use of Arpro for the body panels means overall weight is reduced by 20%. It is also 100% recyclable which helps add to its environmental credentials.
The ME.WE uses Arpro as its side panels and for the bumper of the vehicle, specifically for impact protection benefits, making it safe not just for the occupants but also pedestrians as it offers enhanced protection during impact compared to metal or injection-moulded plastics.

While the company claims that the material is resilient in terms of being resistant to chemicals and liquids, it is unclear whether the material will need to be treated or coated for longevity against UV. However, the material does allow freedom of design and geometry. Its flexibility means that it can be easily moulded into any almost any shape.

This has the additional benefit of potentially allowing panels to be removable and replaceable for customisation. Different colours and patterns on the exterior surface will enable the ME.VE to be adapted to personal tastes.

Paul Compton, JSP President and Chief Executive Officer – Europe, Middle-East and Africa, explains: "The ME.WE concept car could offer drivers and passengers a new experience of vehicle style, comfort and efficiency. It also showcases how ARPRO can be a versatile solution offering a myriad of benefits, from efficiency and safety advantages, to new innovations in customising vehicle exteriors. It is a completely different approach to vehicle design and manufacturing."

JSP is certainly not alone in the market, particularly when it comes to providing foams to the automotive industry. Zotefoams based in Surrey has seen the use of advanced engineering foams increase significantly in the last ten years as it has been able to apply its materials to increasing areas of a vehicle. However, while the market has grown Zotefoams remain out of sight, at least for the time being.

It supplies closed cell foams damping, sealing and insulation to the automotive industry. It says that the use of as to manage noise, vibration, and harshness are long gone and 'functional foams' are now used throughout a vehicle to reduce weight and cost.

Its AZote is a polyolefin foam that has high resistance to most chemicals and greases including brake fluid and coolants. It also has practically no water absorption asbnd low transmission of water vapour. It is available in densities from 15 to 115kg/m3 and is based on LDPE, HDPE and EVA copolymers.

The Zotek N is its new range of high performance foam based on polymide (nylon). It has good high temperature resistance and is used in some engine compartments. Consequently, it is compatible with hydrocarbons such as oil and fuels.

Its Azote and Zotek N foams are physically expanded in an open environment using pure nitrogen allowing them to be formed relatively stress free and with an exceptionally regular cell size and structure.

This absence of chemical foaming agents also removes a major source of VOCs, and means the materials have low fogging – the chemical contamination or volatile additives or constituents in the polymeric material. Similarly this helps to reduce odour and what is commonly identified as that, 'new car smell'.

Both the AZote and Zotek N allow the efficient creation of an endless number of shapes using conventional foam conversion techniques such as routing, water jet cutting, die cutting, sawing, and heat lamination. They can also be thermoformed in to complex shapes allowing designers the ability to experiment with geometry and more complex shapes.

This has been used to add functionality to some parts such as a gasket and filler. The design allowed the reduction in adhesive and release papers by providing a tight friction fit.

The use of engineering foam for automotive application is continuing as the material is able to go hotter. It has the major advantage of being easily formable and relatively low cost. Whether, however, it will be able to become a visible part of a car body remains to be seen.

Top 10 properties of engineering foam
1. Excellent impact absorbing properties
2. Non-toxic
3. Good thermal insulation
4. Lightweight
5. Non-corrosive
6. Moisture and chemical resistant
7. Various finishes and colours
8. Low water absorption values
9. Low Cost
10. Can be treated with flame retardant

Justin Cunningham

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