The low-pressure die casting process (LP casting for short) enables the production of high-quality castings with outstanding mechanical properties, especially using the light metal aluminum. Low-pressure die casting is preferably used for the production of solid castings with thick walls. The process is well known for casting light alloy wheels for automobiles, chassis components with high safety requirements or drive components and housings.
The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, headquartered in Bremen, Germany, offers application-oriented research and development in the field of casting technology with a focus on pressure-supported casting processes such as high pressure die casting, low-pressure die casting, and pressure-supported investment casting. Since 2015, Fraunhofer IFAM has been offering facilities and technical assets for low-pressure casting.
A new low-pressure die casting plant for industry-related applied research has been available at the Wolfsburg site since spring 2021. The technical asset offers an innovation for low-pressure die casting: it enables conventional melting and casting of aluminum as well as high melting metals such as copper. This multi-functionality is made possible by a novel "crucible quick-change system" in combination with a special melting technology that offers both direct and indirect inductive melting. In this way, conventional metals such as aluminum, copper, brass, bronze, magnesium or steel can be melted, but also non-metallic melts such as salt mixtures can be melted and cast. This technology enables the industrializable production of high quality salt cores in a low pressure casting process. Salt cores, known as "lost cores", are currently the focus of developments for use in the high pressure die casting process for the production of hollow cast components such as engine and battery housings.
The new low-pressure die casting system offers a melting performance of max. 130 kW for a melting temperature of up to 1,650 °C. The melt volume is 110 liters and the casting pressure up to 1.0 bar. The lower mounting surface of 1,310 x 1,290 mm² can accommodate molds with a total weight of up to 3,500 kg. The upper mounting surface of 1,200 x 1,200 mm² allows a clamping force of max. 60 t. A vertically movable furnace chamber allows free accessibility of the melting crucible and thus fast alloy changes. In addition to the flexible processing of different melts, the plant can also serve conventional steel molds as well as sand or semi-molds and thus currently offers the highest flexibility and maximum innovation potential in the field of casting technology research.
The new plant concept was developed in collaboration with TEGISA Giessereianlagen und Industrieöfen GmbH. It is based on a prototype of this new plant concept, which was first put into operation at Fraunhofer IFAM in Bremen in 2015. Since then, this first LP die casting plant of this new design has been successfully used and further developed for many years, in particular for casting copper, brass and salt. Currently, the plant concept of the prototype is being further developed for the casting of steel.
In order to expand its range of services for conventional aluminum low-pressure casting, Fraunhofer IFAM has invested in a further industry-standard low-pressure die casting system of the type KURTZ AL 16-12. The series plant will soon be added to the Fraunhofer IFAM portfolio in the area of low-pressure die casting and technologically rounded off. Commissioning will take place before the end of 2021.
Research is currently focusing on a wide variety of technological approaches. Examples include composite casting for the integration of metallic structures and profiles (made of aluminum or steel) directly into the cast component, the combination of low-pressure die casting processes with non-metallic primary or forming processes (e.g. sheet metal forming or plastic injection molding), or the production of cast rotors for electric drives using low-pressure die casting - a technology which has so far been dominated by the high pressure die casting process. The extensive know-how for casting lost cores - especially from salt - can be expanded in the future to near-series implementation thanks to the new, larger plant technology. And the novel possibilities for casting copper in low-pressure die casting offer entirely new potential for producing components with high thermal and electrical conductivity - especially for the electrically driven future.