Hot-Strip Mill
In the hot-strip mill, 10-inch-thick slabs weighing up to 20 tons are heated to about 2,350�F and fed consecutively through a series of 12 rolling stands. Each stand squeezes the slab, making it thinner and longer, until it is a quarter of an inch or less in thickness and more than half a mile long. The finished product is cooled and wound into coils. Some hot-rolled steel made at Burns Harbor is sold directly to customers, who form it into products such as automotive frames, mower decks, machinery and tubing. Most of the hot-rolled steel, however, is delivered to the Division’s cold-sheet mill or the Galvanized Products Division at Lackawanna for further processing.

Cold-Sheet Mill
The cold-sheet mill complex puts the finishing touches on the steel. Coils of hot-rolled sheet are unwound, cleaned, welded one to another and passed through a five-stand tandem mill. The tandem mill reduces the thickness, or gauge, of the steel sheet to exact customer specifications — sometimes as thin as .018 inch. After cold reduction, the steel again is cut and wound into coils and then batch annealed, or heat treated, to make it "softer" and easier to form. Finally, the sheet is rolled in the temper mill, which restores its proper hardness, improves its flatness and gives it the desired surface texture. Computer systems and shape controls in the tandem and temper mills ensure consistency and flatness throughout the sheet.

Coating Lines
Burns Harbor’s hot-dip coating line, one of the most technologically advanced in the world, is capable of making both galvanized and galvannealed sheets.

The line produces uniformly coated sheets with superior surface quality and excellent corrosion resistance, primarily for use by automotive customers. A smaller electro-galvanizing line also is located at Burns Harbor.

In addition, the Division participates in a joint-venture electrolytic coating facility located in Walbridge, Ohio. The Walbridge line produces electro-galvanized sheet and also applies zinc/nickel and organic coatings to cold-rolled sheet made at Burns Harbor.

Galvanized Products Division
Burns Harbor’s Galvanized Products Division, located in Lackawanna, N.Y., near Buffalo, produces cold-rolled and hot-dip galvanized sheet from bands of hot-rolled steel made at Burns Harbor.

Plate Mills
With its 110-inch and 160-inch plate mills, Burns Harbor has the largest platemaking capacity of any plant in North America. To form plate, a steel slab, which can weigh more than 20 tons and measure over a foot thick, is heated to about 2,350�F and then passed back and forth between heavy rolls in two successive mill stands. In the first mill stand, or "roughing" mill, the slab is rolled to the desired finished width, while at the same time becoming thinner and longer. The "finishing" mill rolls the steel to finished thickness and length. The plate then passes through the remainder of the mill where it is leveled, trimmed, marked and prepared for shipping. The 110-inch plate mill is capable of rolling plates from 3/16 to 1-inch thick, while the 160-inch mill can roll plates up to 15-inches thick.