Rolling is a type of metalworking process in which a type of metal stock gets sent through one or more pairs of rolls, which reduces the thickness of the stock and makes it uniform. Think of the way you use a rolling pin on top of dough—you’re essentially doing that, but adding another “rolling pin” underneath and feeding the “dough” (the metal) through the two rolls.
There are multiple kinds of rolling processes, which are classified based on the temperature of the metal being rolled. And even within the realms of hot and cold rolling, there are numerous subcategories of metal rolling, including channel rolling in Phoenix, AZ.
Here’s a quick overview of what you should know about both hot and cold rolling.
Hot rolling encompasses any type of rolling process that occurs above the recrystallization temperature of the material being formed. After metal grains deform during processing, they then recrystallize and form a structure that prevents the metal from hardening.
Usually in a hot rolling process you’re starting off with large pieces of metal, which may be fed directly into the rolling mills at the correct temperature. If you’re working with a smaller operation, though, the material will likely have started at room temperature, so you’ll need to heat it up before you can proceed with the rolling process. You’d do so in a soaking pit powered by oil or gas fires, or, if you’re in a smaller work environment, you could use induction heating processes. In either case, the temperature at which the material is heated must remain above the recrystallization temperature, which again will vary depending on the kind of metal you are to roll.
Hot-rolled metals usually don’t have much directionality or deformation-induced stresses. However, if the metal does not cool uniformly, that could result in some residual stresses forming. This tends to occur most frequently in shapes with non-uniform cross sections, like I-beams.
Hot rolling is most commonly used to create sheet metal or simple types of cross-sections for applications such as railroad tracks. You’ll also find it used in the creation of pipes, tubes, water heaters, truck frames, discs, doors, shelving, metal buildings, guardrails and more.
If hot rolling encompasses all processes that occur over the recrystallization temperature, it stands to reason, then, that cold rolling encompasses all rolling processes that occur below that temperature. Generally, this means the process is performed at room temperature, but not always.
Working with the metal at cooler temperatures increases its strength with strain hardening of up to 20 percent. It also results in an improved surface finish and creates tighter tolerances.
Shapes that are most commonly created from cold rolling include sheets, rods, strips and bars, though other shapes can be cold-rolled if the cross section is mostly uniform and there is a smaller transverse dimension. However, it’s important to note that cold rolling shapes requires the fabricator to perform a number of shaping operations that can add some steps to the overall process.
For more information about channel rolling in Phoenix, AZ and the various other types of metal rolling, we encourage you to contact the team at Metal Pro Inc. today.