Feb 2 2006
Future cars will be far lighter – but just as strong – through new advances in a casting process that uses super lightweight magnesium alloys.
The technology, called T-Mag, consistently produces high-integrity magnesium alloy castings from permanent moulds, free of porosity and other defects.
T-Mag was developed by a team of research engineers from Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO).
T-Mag can cast lightweight magnesium-alloy engine blocks that will be only two-thirds the weight of current aluminium alloy blocks and less than one third the weight of cast iron blocks– a prospect that is already arousing the interest of high-performance car manufacturers in Europe.
It will also be possible to cast high-integrity magnesium alloy wheels. Current casting technology cannot produce wheels of sufficient integrity to be safe and practical at an acceptable cost.
A pilot-scale unit built for research and development has already produced successful demonstration magnesium castings, including road wheels, and blocks for a 750cc, water-cooled, motorcycle engine will be cast shortly.
CSIRO believes that T-Mag’s technical and economic attributes will give it a competitive advantage over current casting technologies, and remove many obstacles to the economic production of high integrity magnesium parts.
Head researcher, Dr Thang Nguyen, describes T-Mag’s novel, integrated design as a critical enabling technology, with a range of applications beyond the high-pressure casting technique currently used to produce 85 per cent of the world’s magnesium alloy components.
High-pressure die casting has limitations which restrict its application to cast many automotive components, one of these limitations is low as-cast yields: typically, it takes six to seven kilograms of metal to produce a 3.5kg casting. The unused metal cannot simply be recycled because re-melting creates oxides and inter-metallic compounds, and both the initial melting process and re-melting the scrap consumes large amounts of energy.
‘T-Mag requires only 3.7kg of alloy for a 3.5kg casting. This reduces recycling, and energy use and saves a lot of melt cost,’ Dr Nguyen says.
T-Mag is a permanent-mould casting process that requires neither applied pressure nor a vacuum to fill the die. The die fills smoothly from the bottom, minimising air entrapment and oxidation, and produces X-ray-quality castings that are virtually free of defects.