Nexcast - The genuine aluminum minimill

Until now, companies investing in new or expanding their flat rolled aluminum capacities have faced a clear trade‑off. The traditional DC (direct chill) route requires casting ingots approximately 700 mm thick, followed by scalping, reheating, and hot rolling on a line typically consisting of roughing and finishing mills with multiple rolling stands. Depending on configuration, this process extends over more than 550 m. It delivers the high quality  demanded by aerospace, automotive, and packaging markets, but at high cost: commercially acceptable economics are generally achieved only at production volumes above 500,000 t/year, limiting DC plants to large‑scale operations.

Continuous casting (CC) has served as the primary alternative, where aluminum is cast directly into a strip-shaped product, which is either coiled immediately or further reduced in an inline hot rolling step. Exploiting the casting heat and eliminating several ingot processing steps significantly lowers capital and operating costs. However, microstructural limitations of conventional CC technology restricts this process mainly to low-alloy commodity grades, serving highly competitive, low‑margin markets.

The innovative Nexcast^® technology, a next generation evolution of the well-established block caster, overcomes these limitations by combining the cost advantages of continuous casting with the capability to produce a wide-ranging portfolio of sophisticated products. At the same time, Nexcast® integrates seamlessly into regional minimill concepts that use either primary aluminum or recycled aluminum as feedstock. The process is particularly well-suited for processing higher-alloyed materials including large volumes of lowgrade post-consumer scrap. Combined with the metallurgical benefits of higher cooling rates compared to conventional DC casting, Nexcast^® represents a new generation of minimill solution for flat-rolled aluminum.

Just theory and sales talk? Not at all. The example of Golden Aluminum Inc. (GAI) illustrates how a U.S. producer has positioned itself for a promising future by partnering with SMS group to co‑develop and build Nexcast^®—the next‑generation, low-cost, high-capability aluminum minimill, now available to select new partners.

Since its founding in 1983, Golden Aluminum has embodied a pioneering minimill approach. Its Fort Lupton plant was originally equipped with a 36 inch wide (914 mm) Swiss block caster forming the core of a compact, fully integrated line that converted molten aluminum directly into hot rolled coils. Although the narrow strip width limited access to many applications, GAI maintained its market position for decades. Success was driven not only by low conversion costs and fast turnaround times, but above all by a key technological advantage over other CC mills: the block caster’s ability to produce sophisticated and challenging alloys that are sold at higher profit margins. For example, the food and beverage industry has for many years been reliably supplied with high-magnesium AA5182 sheet produced on the block caster. In general, GAI’s portfolio today focuses almost entirely on high magnesium alloys for packaging, automotive, and construction applications.

Over time, and despite several refurbishments, the block caster reached its end of service life, prompting GAI to seek a replacement. This created an opportunity to capitalize on decades of operational experience and fundamentally redesign a next‑generation block caster. 

At that point, GAI was already working with SMS group on scaling the block caster up to a modern strip width of two meters under the Nexcast^® brand. With basic engineering completed and key components tested in our Hilchenbach workshop, the new challenge became adapting that refined design to a narrower width. A seamless replacement was equivalent of open‑heart surgery and any failure would have jeopardized Golden Aluminum’s future, with no fallback option.

Building on the foundation of the new wide-strip caster design, SMS group’s engineering and research teams adapted and refined the concept. To reduce project risk, this phase included a prototype-based strategy with in‑house pre‑assembly, integration of new mechanical equipment and automation with state-of-the-art process models, and comprehensive test runs to simulate load conditions and optimize setup parameters. 

At the Fort Lupton site, extensive preparations ensured a smooth shutdown with minimal production downtime. The e‑house, hydraulics, piping, and cabling were pre‑assembled to enable a single complete stoppage. Dismantling the old caster and installing the new one were accomplished jointly within just two weeks. Thanks to careful planning and close cooperation between GAI, SMS group, and installation partners, Nexcast^® produced its first hot‑rolled coil, and production resumed only four weeks after installation began. All mechanical and automation systems—including interfaces to legacy equipment—operated reliably from day one.

Hot commissioning required tight metallurgical and logistical coordination, as each commissioning cast required refilling and cleaning the melting furnaces, cleaning the molten metal transfer system, and replacing the casting nozzle tip. Close teamwork ensured these repeated steps were carried out efficiently and safely. 

Within the first month of operation, the line reached full production. Continuous casting campaigns of up to 60 hours and smooth on the fly alloy changes demonstrated Nexcast^® reliability and flexibility. Following successful commissioning and issuing of the final acceptance in August 2025, SMS group and GAI have continued their collaboration, adding automation functions, validating the cooling model, and optimizing HMI layouts—thus driving ongoing improvements in performance and usability.

In the first few months after replacing the caster, GAI achieved a series of production records while delivering significant quality improvements, including reduced edge and surface cracking, higher yield, and increased downstream throughput. By 2028, GAI expects Nexcast® to boost finished product output by 25%, while providing sufficient casting capacity to produce test coils for ongoing product and market development.

Nexcast^® represents a genuine minimill solution, producing hot‑rolled aluminum coils from molten metal in a single line just 55 m long. Now fully operational and ready for wider adoption, the technology will continue to be optimized for new applications and has the potential to become a key enabler of more sustainable, future‑focused aluminum production. 

With Nexcast^®, the expert team at SMS now has an even broader portfolio of first class solutions at its disposal to meet the needs of its customers. A reference visit to Golden Aluminum offers the opportunity to assess the performance of the new caster firsthand.