A lightweight yet robust oil sump moulded from a heat-stabilised, glass-fibre reinforced grade of Zytel 66 nylon resin from DuPont, has been incorporated by Scania in its new Euro 6 engines.
The application was produced in Sweden by the Plastal Group AB, with the material, design and processing support of DuPont representatives in the country and across Europe, and the input of prototype specialists Idé-Pro of Skive, Denmark.
The adoption of the DuPont material for this application – a first for the truck market and only the second development for commercial production vehicles worldwide – has enabled a reduction in component weight by over 50%, or 6kg, versus its aluminium predecessor, to improve fuel economy and reduce emissions, as well as dampen engine noise to help meet Euro 6 noise emission standards.
The particular grade of Zytel used is a 35% glass fibre reinforced, heat stabilised and lubricated polyamide 66 that is considered a material of choice for harsh, under-the-hood applications involving high temperatures and oil. It has a low melt viscosity so readily fills thin section moulds and offers fast set up times.
Having settled on the initial design and material, Scania contacted Idé-Pro to undertake the first steps in the parts’ development. Idé-Pro not only produces tools and moulds parts, but also offers the development tools and expertise needed during the prototype stage. In such a way the design of the mould could be optimised to minimise warpage. DuPont also assisted Scania in refining the sump’s design and the production process, particularly with regard to achieving a consistently tight seal between the sump and the engine. This required very precise tolerance control of a large component, measuring 847 x 467 x 203mm, achieved by comprehensive mould flow analyses, prototype testing and ongoing optimisation of processing parameters. Ribbing on the underside of the sump also plays a key role.
Its effectiveness in this role was tested at DuPont’s European Technical Centre in Geneva, where a high-speed impact compressed air cannon was used to fire steel balls at an angle of 45° and at a speed of 50mph at the sump. These tests confirmed that the ribs effectively dissipate the impact energy, becoming damaged in the process, whilst the structural integrity of the sump remains preserved.
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