Casting is one of the oldest manufacturing processes, in which liquid metal is poured into a mold to produce components. While this process has been known for thousands of years, the materials and technologies used have constantly evolved. Nowadays, metal permanent molds are often used for the production of casting molds, which have to withstand particularly high thermal and mechanical loads. A common choice for these molds is hot-work tool steel, a material that is widely used due to its heat resistance and durability. The desired geometry can be worked out of the steel using machining processes, but this is associated with high material and production costs and limited possibilities for changing the shape.

However, a new sand mold must be produced for each part - a time-consuming and cost-intensive process. In addition, the sand casting process results in a surface that requires extensive mechanical finishing in order to achieve the desired surface evenness and quality

There is therefore a gap between the sand casting and permanent mold casting processes for small batches and medium-sized productions. One potential solution is reusable molds made of concrete, which must, however, be particularly resistant to high temperatures for use in the foundry.

Together with the North Hessian foundry WVG alu-tec, the University of Kassel is realizing casting ideas made of alkali-activated high-performance concretes for use in small series production. The mineral mold is to be used to produce components for the electrical industry, medical technology and the furniture industry.

On the one hand, concrete molds are to be produced by casting, but on the other hand, the conventional method of producing molds by machining is to be transferred to semi-finished concrete products and the desired geometry milled from a concrete raw block. A particular challenge in the composition of the concrete is therefore its ability to be milled while maintaining sufficient strength and avoiding harmful milling dust.