Bert Suffis, application sales manager at JSP, says that the structure, comprising an Arpro core joined to two thin outer sheets of steel or aluminium, is around 30% lighter than a traditionally-made chassis.
Such a chassis has recently been incorporated into a new generation of electric vehicle-the QBeak, developed by Danish car manufacturer EcoMove and due for commercial launch later this year.
"Inrekor is very scalable: there's no huge investment in stamping and metal forming," says Suffis. "That's usually a large hurdle for a small company."
Arpro parts themselves, which have been used in seat cushions, bumpers and many other areas of the car, also require relatively inexpensive tooling; aluminium-based tools rather than the hardened steel needed for injection moulding tools.
Lower pressure
This is because the parts are foamed and so require lower pressure and they are generally made in lower volumes, using steam chest moulding rather than injection moulding.
The Inrekor-based chassis will be crucial in the development of the emerging generation of small electric vehicles, Suffis believes.
"The early adopters will be the new car makers, but I'm convinced that existing vehicles might begin to use Inrekor in their next-generation sub systems," he says.
Another recent use of Inrekor was to protect the fuel 'bladder' in an Aston Martin racing car. Because Inrekor parts can be made flexibly, and relatively cheaply, it allowed the designers to tailor the product to the exact needs of the car.
"The key advantage in this application - other than the weight saving - was the absolute lack of investment needed," says Suffis.
Making the part from composites, as is usually the case, would be far more expensive and time-consuming, he says. At the same time, a composite system would need to be built and installed within the roll cage. The Inrekor part can be created from a number of separate components, and retrofitted 'piece by piece' - after the roll cage has been welded into place.
"It's like keyhole surgery," says Suffis. "It means the fuel bladder can be made smaller - allowing it to be tuned for certain races."
Aston Martin wants this installation to become common across its GT range, before using it across its GTE, GT3 and GT4 ranges.
Combining techniques
Plastics techniques are also being combined in order to streamline production. One technique, which combines injection moulding and thermoforming in a single process, could soon be used to speed up production of semi-structural automotive components.
The three-year SpriForm project, whose partners include chemicals group Lanxess, machinery firm KraussMaffei and Audi, was set up to develop faster ways of making lightweight structural components for mass production.
"I expect to see parts made using this technology within two years," says Nicolas Beyl, director of technology at KraussMaffei.
He says that parts such as instrument panel carriers, seat backs and front end carriers could be made by first thermoforming a heated plastic sheet into shape, then overmoulding (or 'back-injecting') structural elements on top of this.
"This is not difficult in a pilot plant, but it is hard to do it as a stable, serial production process with automation for 300,000 parts," says Beyl.
The aim of the SpriForm project was to combine these two techniques in an automated fashion, making it suitable for mass production.
Taking off
One reason why the technique has taken off is the emergence of 'organic sheets', in which glass or carbon fibres are impregnated with polyamide.
These light, stiff sheets are thermoformed into shape, inserted into a special injection mould tool, then back-injected with ribs or other structural features.
"You also need to mould a seal around the edge of the sheet, where the fibres are exposed," says Beyl.
The technique could produce parts with a cycle time of around 1 minute - a fraction of the 10 minutes it would take using RTM.
Audi is already using 'organic sheets' commercially, in a front-end system that combines thermoforming and injection moulding - but the two processes are carried out separately.
"In this case, the sheets are thermoformed, cooled, then back injected afterwards," says Beyl.
He says that the 'integrated' technique has several advantages: it replaces two steps with a single one, which saves money, while back-injecting directly onto a heated sheet produces a much better bond.
In recent years, metal fuel tanks and bumpers have all but disappeared; plastic accelerator pedals, underbonnet components and body panels are commonplace.
Now, new materials like organic sheets, CFRP and LFRTs are opening up exciting new opportunities in weight savings for mass-market cars.
