How Rolling Mills Work in Steelmaking

Metal cylinders produced by a rolling mill

Rolling is a common metalworking process used during the production of steel. It involves passing a sheet of steel through multiple rollers. Some rolling processes use two rollers, whereas others use four or more rollers. Regardless, as the steel passes through the rollers, it develops a uniform thickness and consistency. To perform rolling, though, steelmaking companies often rely on a rolling mill. What is a rolling mill exactly, and how does it work in steelmaking?

What Is a Rolling Mill?

A rolling mill is a machine that, as the name suggests, is designed to manipulate sheet metal by rolling it. Rolling mills contain at least one pair of rollers. Steelmaking companies use them to manipulate the physical properties of raw sheet metal, including steel sheet metal. By passing sheet metal through a rolling mill, its physical properties will change.

While they’ve evolved over the years, rolling mills have been around for centuries. Many historians, in fact, believe Leonardo Da Vinci was responsible for pioneering the first rolling mill. In one of his drawings, Da Vinci designed a rolling mill featuring a pair of rollers. With that said, modern-day rolling mills didn’t emerge until the 19th century. In 1820, Bedlington Ironworks produced one of the world’s first rail-based rolling mills. Rail-based rolling mills are those that are designed to create long and narrow beams or “rails” of metal.

How Rolling Mills Work in Steelmaking

Rolling mills work by using multiple rollers to manipulate the physical properties of sheet metal. In steelmaking, they offer a uniform thickness and consistency for the steel sheet metal with which they are used. Rolling mills contain rollers that squeeze and compress sheet metal as it passes through them. Therefore, the sheet metal may have an inconsistent size or shape beforehand. After passing through the rollers in a rolling mill, however, the sheet metal will develop a uniform size and shape.

It’s important to note that rolling mills support both cold rolling and hot rolling processes. Cold rolling means the sheet metal is pressed between the rollers at or near room temperature. Hot rolling, on the other, means the sheet metal is pressed between the rollers at a temperature above the metal’s recrystallization point. Cold rolling allows for the production of stronger and more durable steel products, whereas hot rolling is a faster and easier rolling process that allows for streamlined production activities. Rolling mills can be used for both cold rolling and hot rolling.