Above: SMS-Meer built the Precision Sizing Mill as part of Steel Dynamics’ expansion.

Steel Dynamics marshals brains and brawn to efficiently deliver precise sizes and shapes

August 2015 - How does a steel producer build out space and install a new special-bar quality mill inches away from an existing mill without disrupting both melt shop and rolling production? It takes a combination of study, expert advice and a willingness to think in a nonlinear way.

The $94 million expansion conceived by Steel Dynamics Inc. for its Pittsboro, Indiana, plant “was studied from many perspectives,” says Barry Schneider, vice president of bar products. The project had to respond to customer needs by creating additional product offerings and stringently controlling size and shape to conform with ever tighter tolerances.

The original plant built by Qualitech Steel Corp., which was run by metallurgical engineer and former North Star Steel executive Gordon Geiger, commissioned its first heat in 1998. Struggling in the face of cheap imports, however, the company was sold through bankruptcy court to SDI in 2002 and restarted as a commercial-quality bar facility in 2004.

“The original Pittsboro plant was designed to go to 1-inch diameter when it was built by Qualitech. When SDI acquired the facility out of bankruptcy, our needs at that time were to produce merchant shapes for our joist division,” says Schneider.

The equipment SDI added back then allowed for production of merchant products (angles, channels, rebar, flats, etc.) as well as rounds up to 9 inches in diameter—but the sweet spot was really between 2 and 6 inches. These are popular sizes for forgers and other customers but SDI’s bar group felt the mill was missing the boat on smaller diameters.

The company analyzed bottlenecks in its existing layout and the applications for all the sizes and grades the mill produced. SDI hired a consultant to expand its understanding of the North American SBQ market as a whole, making certain executives didn’t suffer from tunnel vision.

“The issue before our expansion was that the equipment that SDI added to make rounds was OK but not of comparable dimensional control quality that our competitors offer,” Schneider says. “Subsequently, we offered limited products less than 25⁄8 inches from the existing 16-inch mill (this refers to the size of billets arriving from the melt shop).

The new 14-inch mill allows Pittsboro “to make very high quality product in this smaller diameter size range that can compete with the best and also allows the mill to make these products at a very high productivity,” he explains.

Must-haves

The bar group had several immediate goals associated with this project. The expansion had to be efficient while increasing the flexibility of order scheduling; preserve the low-cost competitive position of SDI bar products; and be able to manufacture products that continuously comply with various Production Part Approval Processes for various automotive, heavy truck and other OEM customers. The project also had to be performed while the 16-inch mill kept rolling and meeting all established quality requirements.

After analysis was complete, SDI shared its goals with mill builders. SMS-Meer was chosen to realize the vision.

The existing mill design includes a 125 tons-per-hour walking beam reheat furnace and three distinct groupings of rolling mills. The bottlenecks were contained within the finishing stands and product handling area. The mill was laid out so that bars larger than 25⁄8 inches were on size after the intermediate mill, where they would be shuttled off to the large-diameter cooling bed. Products smaller than 25⁄8 inches and merchant bar continued across the large-diameter cooling bed but then were moved to the finishing stand for further size reductions.

“We were only spending 5 percent of mill time, more or less, running products below 25⁄8 inches, due to our productivity limitations and our size control,” says Schneider. “We had some really nice assets that were just being underutilized.”

Relocating those assets was cost prohibitive. SDI’s solution was to turn the single mill line into two separate rolling mills, with each mill retaining the ability to operate independently.

To work on this while operating a functional production line required SDI to get creative. It laid out the new mill starting 3 feet above the existing mill’s pass line and then turned it 90 degrees. “We affectionately call it Turn 1, in reference to the Indianapolis Speedway,” says Schneider.

“When we approached the machine builders about this idea, it presented no concerns. Many rod/wire mills do the very same thing.” In many parts of the world, he adds, equipment suppliers are forced to work within the space constraints that steel mills have. “Here in the States, we tend to think very linearly and space is less of a concern.”

Size control

The cornerstone of the expansion was to install a Precision Sizing Mill (PSM). “Precision sizing is what our customers are asking for more and more,” according to Schneider. “The forging customers are very technically advanced. They have evolved into using closed dies for many of the products below 3 inches. Precision sizing allows the mill to produce a bar repeatedly that is the same so that the forging customer can cut a length and be confident it will produce the same weight time and time again,” he explains.

The diameter has to be very closely controlled for this level of reliability and repeatability. Cold finishers demand precise sizing and roundness, which “directly impacts their productivity and costs in the finished product.”

Installation of the PSM required digging out basements and pouring heavy foundations, according to Schneider.

Finally, new bar handling and bundling equipment was installed to complete the second mill.

The SMS-Meer sizing equipment uses three rolls that converge at each stand, four stands in total. “This three-roll technology allows for the diameter to be monitored closely and controlled through feedback from high-speed measurements,” says Schneider. 

The company hired 50 additional employees to run the new mill and round out the shipping, sales and bar finishing departments.

End user demand

Schneider concedes the market for engineered bar was soft during the first half of 2015. “Import pressure is much stronger than anything we have historically seen.” At the same time, that demand weakened in the energy sector, mining and heavy equipment.

However, SDI foresees SBQ demand will increase through 2020. “The development of new products remains very strong. The automotive market has been very robust and is projected to follow that trend, as has industrial truck.

“The need for more demanding products and for the supply chain to be efficient” will favor North American producers over the next five years, he adds.

Since starting up the second mill last autumn, Pittsboro has been “able to earn some market share,” while retaining high-value PPAP customers in a seamless fashion. “The facility was shaped around their needs.” This year, says Schneider, SDI is working with customers “to approve our new facility” and work the new mill’s products into their own production schedules. MM