Composite provides super integrated door module

Verton MFX long-glass-fibre-reinforced polypropylene composite is central to the 'first of its type' door module carrier in the all new Mazda 6 series mid-size car launched in Europe in January 2003.

Verton MFX long-glass-fibre-reinforced polypropylene composite from LNP Engineering Plastics, a GE Plastics company, is central to the 'first of its type' door module carrier in the all new Mazda 6 series mid-size car launched in Europe in January 2003.

Unlike earlier modules made from steel-stamped parts or press moulded glass-mat reinforced thermoplastics, the Mazda's module carrier features a low viscosity, high flow Verton MFX polypropylene composite with a high crystalline structure that can be injection compression moulded or injection moulded.

As a result, the module carrier can be moulded to thinner wall sections and is much stronger, lighter, is highly recyclable and allows the integration of functions, to deliver lower production costs.

The Mazda door module, which combines parts and integrates functions, holds the speakers, latch assembly, door lock actuator and glass window regulator, and provides sound damping and security improvement, as well as acting as a seal against the elements.

"A new material and injection moulding technique were developed for this large part.

The technique reduces the pressure and shear on the long glass fibres compared to conventional injection moulding processes", explains Otto de Bont, European Marketing Manager for LNP.

"As a result, the glass fibres are significantly longer after moulding than with conventional injection moulding.

The longer glass fibre length means higher impact strength", he says.

In addition, the process delivers low moulded-in stress for exceptional dimensional control.

Further complementing the Mazda module carrier, the Verton MFX composite provides improved high-temperature fatigue resistance compared to similar nylon-based composites.

It also gives a resin-rich, high quality surface finish.

Another advantage of the proprietary Verton MFX polypropylene composite is its extremely low viscosity, which increases flow by over 30% compared with conventional long-glass-fibre-reinforced polypropylene.

As well as allowing thinner moulding sections, low viscosity makes part integration possible.

Moreover, integration and fewer parts reduces processing costs.

In turn they lead to lower cost for the trim panel and reduced assembly time with fewer handling problems because assembly is less precision dependent.

Mazda intends to use the composite and new processing technology to develop other functional modules for use in new models.

According to Paul Willems, Industrial Design Leader for LNP in Europe: "The next step to driving increased design flexibility and production economies will be development of the super integrated door module that integrates the structural components as well as the functional ones.

This will include the window regulator rails and gear housing, enclosure for electronics and also the base for a full length armrest support.

"This type of integration is very new and the Mazda development provides the bridge between what has been achieved to date and what will be accomplished in the future", he says.

In taking the next step, development of the super integrated door module, materials will need to satisfy new as well as higher performance criteria including high mechanical strength at temperatures ranging from -40 to +80C.

During the opening/closing of the window there are very high forces exerted on the carrier which are increased by the weight of the traditional steel window regulator mechanism.

When closed there is a permanent pressure on the system which at high temperatures presents a problem in respect of dimensional stability as temperatures can build up to 80-90øC within the door module.

LNP is confident that it has the materials solution to satisfy all performance criteria including that for the window regulator system.

In this component the standard solution is to use a metal carrier and a plastic sliding part together with large quantities of lubricant.

LNP can provide an all plastics solution where the complete regulator system is made of plastics and no external lubricant is required.

This solution involves moulding the rails in Verton MFX composite as an integrated part of the door module, while the slides are moulded in a special Lubricomp, an internally lubricated compound based on acetal and teflon, that achieves self-lubrication.

The resin-rich, higher-quality surface finish of the Verton polypropylene composite ensures that the slides operate smoothly on the integrated rails.

An additional benefit is that the near class A surface finish achieved with Verton allows for its use in applications exposed to the interior of the car.

Integrating visible components such as the door handle housing or vent outlets into the door module reduces the complexity and cost of the trim panel, which in turn lowers the total cost of the door assembly.

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