Sand casting in car manufacturing
Casting – for many an old and antiquated manufacturing process. Old yes, but outdated? That may be so at first sight, but the reality is different. Indeed, the world’s oldest manufacturing process still has some surprises in store. Take sand casting, for instance.
For a long time, sand casting aluminium was a niche application with respect to automotive components. However, its market share is growing. This is due not least to a high level of design freedom, process reliability and quality, not to mention low costs compared to other casting processes.
Lighter components for the drivetrain and chassis
The classic sand casting process, which aluminium foundries are making use of today, relies on gravity to fill the die in order to manufacture an array of components for the drivetrain and chassis of cars and commercial vehicles. These include gearbox cross members, trapezoidal links, the engine bracket, anti-roll bars, wheel carriers, consoles and the auxiliary frame, as well as intake manifolds and oil sumps.
However, the potential of aluminium for lightweight construction cannot be fully exploited because the process determines the components’ wall thickness, which cannot normally be less than five millimetres. For components with a large surface area, e.g. oil sumps, three millimetres is entirely sufficient, but this is not feasible with conventional sand casting.
However, process development measures – leading to low-pressure sand casting – have made this problem a thing of the past. Sand casting is thus benefitting from new options for the economic manufacture of highly resilient aluminium components. While low-pressure sand casting will not replace conventional sand casting, it will offer new applications that were hitherto unfeasible.
Better, faster, cheaper
Low-pressure sand casting combines classic aluminium sand casting with low-pressure chill casting. In Germany it was developed by companies including Honsel AG in Meschede and KSM Castings GmbH in Hildesheim.
In Switzerland, meanwhile, GF Automotive in Schaffhausen is a respected supplier. Its production facilities are located in Garching, close to the Bavarian city of Munich. Using the auxiliary frame and wheel carriers as an example, the company has demonstrated the process’s advantages and that it now offers an alternative to pressure and chill casting.
What all processes have in common is that because the molten metal rises up from below, there is almost no swirling as the die is filled. This results in better filling of the die and very good mechanical properties, both of which are sought by the car industry for chassis safety components.