SDI Aluminum Mill Ramp-Up Accelerates as Columbus Moves Toward Higher Utilisation

Steel Dynamics

SDI aluminum mill ramp-up is moving faster than the company previously expected. Steel Dynamics now expects its Columbus aluminum mill to exit 2026 at 90pc capacity utilisation. That is well above its earlier forecast of 75pc. As a result, SDI aluminum mill ramp-up now looks stronger and more confident.

The change matters because Columbus is a major new flat-rolled aluminum asset. The Mississippi plant has annual capacity of 650,000 metric tonnes. Steel Dynamics operates it through Aluminum Dynamics within its flat-rolled aluminum segment. Therefore, faster ramp-up could strengthen domestic flat-rolled aluminum supply.

Management also pointed to a practical reason for the improved forecast. It said aluminum mill commissioning is more forgiving than steel mill commissioning. Steel systems require tighter integration across the entire line. Meanwhile, aluminum start-ups can recover more easily from isolated disruptions.

Columbus Aluminum Mill Shows Faster Start-Up Progress

Columbus aluminum mill progress has improved as more equipment moves into operation. The company began producing from the first of its two tandem mills during the fourth quarter. It also expects the first CASH line to begin operating by the end of March. Consequently, the plant is moving closer to full finished product capability.

That final processing step is critical for automotive aluminum supply. Steel Dynamics said the first CASH line is the last major piece needed for finished flat-rolled automotive products. This means Columbus is approaching a more valuable commercial phase. Therefore, the plant’s product mix could shift upward in quality and margin.

The company remains cautious on near-term output disclosure. It declined to state the current utilisation rate at Columbus. It also warned that shipping rates do not necessarily reflect actual production rates. However, December shipments still reached 10,000t of flat-rolled aluminum products, which signals ongoing commercial progress.

Flat-Rolled Aluminum Products Are Expanding Despite Ongoing Losses

Flat-rolled aluminum products from Columbus are already supporting the broader market. Steel Dynamics has been producing aluminum hot-rolled coil, or hot band, during Novelis’ extended outage in Oswego. Some of that material is being converted by other processors. As a result, Columbus is already influencing supply even before full downstream completion.

Product development is also advancing. The company added 5182 alloy hot band during the latest quarter after previously producing only 5754 alloy. That widens its product offering and improves commercial flexibility. Meanwhile, it helps position the mill for a broader customer base.

Financially, the aluminum segment is still absorbing start-up pressure. Fourth-quarter operating losses widened to $47mn, while revenue more than doubled to $158mn. Full-year losses also increased sharply, even as revenue rose 40pc. Therefore, the core question is no longer demand, but how quickly operating leverage can improve.

The faster SDI aluminum mill ramp-up suggests management now sees a clearer path through commissioning. The company’s past problems at Sinton likely made it cautious at first. However, Columbus appears to be progressing with fewer structural setbacks. That difference could matter greatly for earnings in 2026.

The Metalnomist Commentary

This update suggests Columbus is moving from commissioning risk toward commercial execution. That is important because new US aluminum rolling capacity can influence both supply balance and automotive sourcing. If SDI keeps ramping smoothly, the market may start focusing less on losses and more on future margin potential.