Rheocasting: Is Semi-Solid the Future?

Electromobility, advanced communication technologies and increasing sustainability requirements are changing which components are cast – and how. A process that was long regarded as a niche solution is now moving into focus: Rheocasting. This semi-solid casting process, a variant of semi-solid metal processing, offers foundries the opportunity to broaden their technological and economic base. At EUROGUSS 2026, the topic will, for the first time, have its own dedicated joint stand.

Written by Editors EUROGUSS 365

Metal casting part with complex internal structure, rectangular shape, placed on a black glossy surface against a dark background.

Person wearing a light blue shirt standing in an industrial setting with a blurred background — Staffan Zetterström is Marketing & Sales Manager at Comptech Rheocasting and present at the EUROGUSS Rheocasting Pavilion.

Rheocasting is not a new technology – but one whose time seems to have come. “

Until now, rheocasting simply wasn’t necessary,” explains Staffan Zetterström, Manager Marketing & Sales at Comptech Rheocasting. “But electromobility and 5G are changing the requirements: components need to be stiffer, more thermally conductive and more material efficient.” And rheocasting is ideally suited to that.

The Basics of the Slurry

Rheocasting is based on a controlled solidification process: the molten metal is cooled in a targeted manner until it partially solidifies. The result is a mixture of solid and liquid phases – a kind of metallic slurry that is then injected into the die. The outcome is a fine-grained microstructure with homogeneous material distribution, resulting in castings with low porosity and high density.

This semi-solid consistency improves the flow characteristics – a clear advantage for thin-walled and complex geometries, such as those used in electric vehicles or heat exchangers. Typical applications also include large structural components in car body construction, CO₂ compressor systems or parts where thermal conductivity is a key design criterion.

Long, narrow metal component with complex structure and reinforcement ribs, isolated against a black background

Opportunities in Thermal Management

Rheocasting is particularly attractive for foundries currently active in low-pressure die casting. “With rheocasting, foundries can make the step towards high-pressure die casting (HPDC) and thus tap into new market segments,” says Zetterström. The reason for this is obvious: while e-mobility is driving the growth of die casting, it is also reducing the number of cast parts in electric vehicles, even as the complexity of the remaining components increases – a paradox that especially smaller and medium-sized foundries are struggling with.

Metal component with multiple parallel cooling fins, rectangular shape, placed on a padded surface

In thermal management, however, new opportunities are emerging, according to Zetterström: “Rheocasting is increasingly competing with extruded heat sinks, achieving thermal conductivities of up to 185 W/mK – while being more cost-efficient to manufacture.” Moreover, the process allows the use of low-alloy aluminium types, making it particularly interesting for structural components in the body-in-white segment. “That includes far more than the familiar battery housings or rear-floor structures of electric cars,” he adds.

Sustainability as a Driver of Development

Ecological factors also contribute to rheocasting’s growing importance. The process enables a reduction of CO₂ emissions at several stages along the value chain.
Firstly, newly developed aluminium alloys are used that already have lower emissions in their production. Secondly, the semi-solid process allows the manufacture of lighter, thinner-walled components that require less material while maintaining the same stability.

“The combination of these effects significantly reduces CO2 emissions during production,” says Zetterström. In the long term, the process could therefore help to improve energy and resource efficiency across the foundry industry – a topic gaining increasing relevance in research and development, particularly in the context of European climate goals and the sustainability strategies of many OEMs.

Rheocasting at EUROGUSS 2026

The growing interest in the process will also be reflected at EUROGUSS 2026, where rheocasting will, for the first time, be represented with its own joint pavilion. Companies such as Comptech Rheocasting will present components, material solutions and research results together with partners. The goal is to bring together manufacturers, users and suppliers, and to make the potential of this technology tangible.

“The pavilion will become the epicentre of rheocasting at EUROGUSS,” says Zetterström. “This is where everyone meets who wants to understand what opportunities semi-solid casting opens up for the die casting industry.”

Rheocasting is less of a revolution than a step towards technical differentiation. Will rheocasting establish itself on a broad scale? That depends on investment readiness and the transfer of know-how. But the signs suggest that the niche is turning into a market.