Plastic makes further inroads

The world’s first all-plastic oil module housing is about to go into series production on Audi’s new A3 2-litre FSI engine.

The innovative design recently received an Automotive Division Award from the Society of Plastics Engineers (SPE), Central Europe, taking first place in the Power Train category (under-the-bonnet/chassis applications).

Jointly developed by Bayer Polymers and automotive component specialist Mann & Hummel, the module, which is about 300g lighter than a traditional aluminum component, includes an oil cooler, pressure sensor, pressure regulator valve and crankcase ventilation system.

Plastic is said to offer a number of economic and technical advantages over conventional aluminium die-cast designs (see panel below).

‘Until now, oil modules have consisted of both plastic and metal parts, but this is the first time that such a part has been completely plastic,’ said Bayer Polymer’s Dr Frank Rothbarth. This has been made possible, he said, largely by the high-performance characteristics of today’s polymers.

The component is made from Durethan AKV 35 H2.0, a 35 percent glass fibre-reinforced polyamide 66 that is specially designed to withstand hightemperatures.

The plastic has a low tendency to warp, and can be worked in such a way as to create a glass fibre-free surface so that no fibres get into the oil circuit.

The material is also said to be highly resistant to alternating stresses (pressure fluctuations). Indeed, microscopic examinations following durability tests showed no damage in critical areas of the moulding due to hydrolysis or chemical attacks from oil additives or decomposition products.

Dr. Rothbarth said that as well as being 300g lighter than a comparable aluminium design, production of the plastic modules is also far more cost effective, and that complex parts can be constructed from plastic at reduced production costs.

For instance, whereas the drill holes, threads, openings and flanges on metal oil modules need some degree of mechanical working, injection moulding can be used to produce a finished plastic component. There is also less scrap, partly due to the smaller number of stages in the production process, while additional functions such as oil cooling, crankcase ventilation, sensors and control or bypass valves are all easily integrated into the design.

Tooling makes for further cost savings, claimed Mann & Hummel. While tooling for a cast aluminum housing lasts for around 100,000 parts, tooling for plastic housing can yield more than a million parts before it needs replacing. Being free of metal, the all-plastic moulded part is also suitable for recycling.

Ulrich Grosser, a design expert at Bayer Polymers, said that this use of polymers is just the tip of the iceberg.

‘In the wake of this breakthrough, we expect many successor projects, ensuring that polyamide finally establishes itself for applications in the engine compartment,’ he said.

Grosser added that work is currently underway to launch series production of other similar oil modules.

Panel: The advantages over metal

Weight savings: a lighter car is more fuel-efficient, and plastics are typically lighter than metals. The low weight of plastics also allows more sophisticated systems and components to be included without additional weight. The proportion of polymer materials in a car has increased from 5 per cent by weight in the early 70s to approx. 15 per cent today.

Low manufacturing cost: injection moulding, blow moulding and various composite-forming processes could save the car industry billions of pounds over traditional steel and aluminium forming methods.

Design flexibility: plastics can be moulded into components of complexgeometries, often replacing several parts in other materials, and offeringintegral fitments that all add up to easier assembly, which helps to reduce assembly line costs.

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