3D printing with sand enables more environmentally friendly foundry technology

3D printing processes for plastics and metals are well established. Largely unknown is printing with powdered starting material. In the binder jetting process, a printer lays sand layer upon sand layer of only 0.24 millimetres thickness on top of each other and prints them locally with a special binder according to the desired geometry. The product then hardens in a microwave.

The Department of Foundry Technology headed by Martin Fehlbier, Head of the Department of Foundry Technology at the University of Kassel, wants to use the process to print casting moulds and cores and make them usable for casting metals. Whereas with casting moulds, the metal is placed on the inside, casting cores make it possible to create complex cavities with undercuts in the product.

 

3D printing for the CO2 balance, sand moulds for die casting

Inorganic 3D sand printing significantly reduces the CO2 footprint and emissions. It does not, for example, use environmentally harmful coal dust additives or organic binder systems. The situation has been different up to now with old-fashioned sand casting processes. The Kassel researchers want to determine parameters and material properties to create simulation models or to expand the application potential. At the same time, the 3D printing process should significantly improve the CO2 balance.

Another research goal is the use of casting moulds and casting cores made of sand in die casting, a common process in industry. This has not been possible so far, but would significantly increase the application possibilities of sand-printed moulds in casting technology, says Fehlbier.

 

Rheo casting for ultra-light materials 

The university is also expanding the research site with a unit for so-called rheo casting. In this process, partially solidified aluminium melts are cast in a doughy state with lower energy input and reduced shrinkage. This leads to a "laminar" mould filling in the casting process, which reduces defects in the finished component and increases the component quality. 

The Kassel research group wants to make rheo casting usable for ultra-light materials - this would open up numerous possibilities, for example to make vehicles or aircraft lighter and thus more sustainable. 

The European Union's React-EU programme funded the investment in the rheo casting unit and the university's 3D printer with a total seven-figure sum. Among other things, the programme is intended to increase the innovative strength of the EU states.