A real success story: The world’s first CSP^® Nexus plant

The process starts with a single-strand curved caster based on a vertical bending concept with liquid core reduction (LCR plus). The strand thickness ranges between 110 and 140 mm – much thicker than in conventional CSP^® plants of 50 to 90 mm. The strand is cast at up to 6 m/min.

By contrast with other thin slab casting and rolling (TSCR) concepts, in which casting and rolling are necessarily linked, the process at CSP^® Nexus is decoupled immediately after casting. A pendulum shear cuts the strand to the precise coil weight, then the material flow is buffered and purposefully transferred.

This transfer to the first furnace takes place at a high temperature level: The casting process itself has temperatures of around 1,150 °C, so no energy-intensive heating is required. The role of the first furnace consists rather in the temperature homogenization of the cross-section and in thermal fine-tuning for the subsequent roughing process. This furnace also allows the buffering of slabs during a work roll change without interrupting the casting process and provides the logistics to add a second strand to increase productivity.

X‑Pact^® Dynamic Furnace Control, integrated into the CSP^® line’s level 2 automation structure, precisely calculates set points for the furnace zone temperature to heat up the slab to the given discharge temperature at the appropriate heating time, acceleration point, and buffer time. The system supports heating and acceleration strategies to reduce energy consumption by lowering furnace zone set points where feasible and/or to increase buffer times by initiating slab acceleration as early as possible, all fully aligned with higher‑level control and planning functions.

The finishing mill consists of a high-pressure descaling unit followed by six mill stands equipped with automatic pass line adjustment and active guiding systems. The entry thickness is between 35 and 60 mm, and the final strip thickness between 25.4 mm (e.g., API grades) and 1.2 mm (e.g., low carbon grades). Width, thickness, and grade changes can be performed flexibly from coil to coil, thanks to the real batch rolling mode.

All finishing stands are fitted with tried-and-tested actuators, such as our CVC^® plus and work roll bending systems. Used in combination with X-Pact^® Profile Contour and Flatness Control (PCFC^®), flexible, efficient, and extremely precise rolling is ensured. CVC^® grinding on the work rolls allows the geometry to be precisely controlled, even during changing sequences. SDI is thus able to adapt its rolling campaigns flexibly to different order situations. This is yet another major advantage compared with other TSCR concepts, which run in endless mode and therefore have wear-optimized roll grindings instead of flexible CVC^® grindings in the final mill stands.

After the rolling process, the strip passes through the laminar cooling section, which features segmented control and edge masking. The cooling section is controlled by the X-Pact^® Cooling Section Control system and is supplemented by the X-Pact^® Microstructure Property Model, with which the ideal product properties for the final hot rolled products can be predicted.

At the center is SMS group’s X‑Pact^® automation ecosystem. This modular software architecture interlinks every plant area within a common framework that covers both X‑Pact basic and process automation solutions. The systems are fully scalable and equipped for future functional expansions including AI‑based optimization, digital twins, and ESG‑compliant reporting tools.

The X‑Pact^® Integrated Process Model (IPM) serves as the plant’s overarching system, orchestrating the individual models and optimizing the process with regard to energy consumption and product quality for API-grade production. It sets up the process prior to rolling in the most energy-efficient way while maintaining the target dimensions and properties.

A further strategic benefit of this end‑to‑end software architecture is the ability to add future functionalities without making any structural modifications, examples here include predictive maintenance, resource and energy optimization, and digitally networked supply chains.

A hard deadline was scheduled for the start of production on the new plant. The only way to get there on time was with our X-Pact^® Plug & Work automation test, which employs a digital twin of the plant to create simulations and perform an exhaustive set of tests. Unlike other projects, where the customer travels to integration test facilities for several weeks, SMS implemented a fully remote testing and training approach for this project. The entire simulation was streamed to the SDI teams via VPN from Germany, including virtualized control desks, local panels, HMI system, and 3D simulation of the digital twin, enabling the customer to operate the plant from the US while the SMS team in Germany held videoconference training. The approach was so successful that it led to additional training orders and enabled the customer’s personnel to be fully fit and ready for operation when the plant came on stream.

SMS group is solidifying its role as a trusted service partner by providing comprehensive lifecycle services for the CSP^® Nexus at SDI Sinton. Under an outsourcing agreement for the management and operation of the mold and segment workshop, SMS is securing reliable plant performance and long-term asset value. Standard technical services, such as inspections, repairs, overhauls, and spare parts for core components, are a central part of our service offerings. In addition, an SMS maintenance and operations expert is on hand to support the customer directly on-site, addressing day-to-day operational needs.

The commissioning of CSP^® Nexus at SDI sets a new benchmark not only for productivity, quality, and energy efficiency, but also for strategic resilience. Future industry requirements are clear: lower CO₂ emissions, greater production flexibility, wider-ranging material portfolios, and reduced operating costs. CSP^® Nexus is equipped to meet these demands and open up new opportunities.

The plant concept is modular: SDI’s Nexus plant was designed for future productivity enhancements, enabling capacity to be expanded beyond 4 million t/year. That makes CSP^® Nexus a genuine alternative to conventional hot strip mills with respect to CAPEX, footprint, maintenance, and efficiency. With documented performance, particularly for API and HSLA steel grades, CSP^® Nexus is positioning itself as a solution for growth sectors such as energy, mobility, and infrastructure.

Validated under real production conditions, the CSP^® Nexus at SDI offers comprehensive, traceable process data and records that demonstrate the technology’s superiority: a scalable, digital, and decarbonizable production platform for next‑generation flat steel.