From 2010, BMW's Landshut plant will boast the world's first foundry with emission-free sand core production. The light-alloy foundry at the BMW plant is introducing a new sand core production method for gravity die-casting, whereby conventional organic binders will be replaced by highly eco-friendly inorganic binders, which generate virtually no pollutant emissions. The introduction of this innovative production method will allow the light-alloy foundry to reduce its emissions of combustion residues by 98 per cent. The plant will completely decommission its current waste air treatment systems by 2010.
The Landshut light-alloy foundry's approximately 1,300 employees currently produce around 1.8 million aluminium and magnesium castings a year, with a total weight of 45,000 tonnes. The product range includes engine components such as cylinder heads and crankcases, structural components and chassis parts such as suspension strut supports, tailgate frames, corner castings and casting nodes for the front and rear axle.
Approximately half the castings produced are gravity die-cast using sand cores. The light-alloy foundry uses some 120 tonnes of sand daily in sand core production. 90 per cent of this volume is recycled. Following an initial pilot operation phase, the BMW Group is now poised to become the world's first manufacturer to use inorganic sand cores in volume production of all engine core components. The inorganic binders used are based on water-soluble alkali silicates (i.e. a water/silica sand solution), resulting in significantly reduced resource consumption.
"Inorganic sand core production positions us at the forefront of the foundry industry," says Dr Wolfgang Blümlhuber, head of the light-alloy foundry. "We see inorganic sand core production as key to competitive operation, particularly in highly industrialised countries with stringent environmental regulations, where manufacturing costs are correspondingly high."
The light-alloy foundry first introduced this reduced-emission production process for use in the manufacturing of aluminium crankcases and cylinder heads for six-cylinder diesel engines. Now inorganic sand core production is gradually being extended to the foundry's entire product range.
In addition to the environmental aspect, the process also has economic and ergonomic benefits. The strength of the resulting light-alloy components is enhanced by the improved, faster solidification of the liquid aluminium during the casting process, as it cools from a temperature of approximately 750º C. The BMW Group is using this light-but-strong design potential as a way of producing energy-saving, fuel-efficient engines capable of higher peak cylinder pressures and increased power density.
The Landshut light-alloy foundry's employees benefit as well, due to substantially enhanced working conditions. Until now, the casting tools had to be blasted with dry ice after every use in order to remove combustion residues. This energy-intensive process can now be dispensed with.
To accompany the introduction of inorganic sand core production, the light-alloy foundry developed new core shooting tools and equipment. The casting equipment has become less complex, since the previously required venting systems can be dispensed with. At the same time, the cooling intensity during the casting process can be increased, thus reducing manufacturing cycle times by around 10 per cent. The simulation technology used in the process and tool development was developed at the BMW Landshut plant too.
"We will be able to fully amortise the investment in tools and equipment, along with our development costs, in the space of just a few years at most thanks to increased productivity, and thanks to savings on tool maintenance, tool and workshop air extraction systems and waste air treatment systems," says Dr Wolfgang Blümlhuber, head of the BMW light-alloy foundry. Specifically, the productivity increase works out at around 10 per cent. Tool maintenance costs will be reduced by half.