Let’s talk about hot rolling steel.

Although the terms “induction bending” and “hot rolling” are often used interchangeably by people on the fringe of the metal-rolling and bending business, the two are quite different processes with quite different goals.

The similarities are:

They both require heating metal hotter than you would want to touch.

The similarities pretty much end there. However, the differences are quite numerous.

Hot rolling is used primarily on steel. Induction bending can be used on any metal, whether it’s an iron alloy or a non-ferrous metal.

Hot rolling is used primarily on large tracts of steel and semi-finished casting products, such as slabs, blooms, and billets, whereas induction bending is used primarily on metal pipes, tunes and springs such as natural gas or petroleum pipelines, industrial grade springs, farming tools, culverts, etc.

Hot rolling is used primarily to flatten or to change the thickness of metal, hence the “rolling” part. Induction bending is used to bend the pipe or tube, hence the “bend” part.

Hot rolling involves heating a huge surface of metal so that it can be flattened or formed in its entirety. Induction bending involves just the specific area that needs to be bent, making it a much less energy-intense process.

Hot rolling requires rollers (obvious, I know) for the rolling process, whereas induction bending does not.

Although both processes use heat to distinguish themselves from cold rolling, there are actually more similarities between hot rolling and cold rolling than between hot rolling and induction bending.

So the processes are quite different and so are the goals. However, there can be overlap and there are times when a decision must be made between induction bending, hot rolling and cold rolling.

Here are six advantages of induction bending over hot or cold rolling, reasons why a steel tube rolling company would prefer induction bending over other methods when it is appropriate for the job:

To begin with, induction bending is more cost-effective, saving the client money in three key areas:

- Labour
- Energy
- Overhead

Labour costs are lower simply because the induction bending process is faster. It is a highly time-efficient process. It takes less time to complete, so the labour costs are less. Simple math.

Energy costs are lower simply because less heat is required. It is a highly energy-efficient process. Keep in mind that where hot rolling required heating a huge piece of metal, the heat in induction bending is laser-targeted to just the specific spots where a bend is needed. One big caveat to report - when cold rolling can be applied, it has an obvious energy-saving advatahge over any heated process, including induction bending

Overhead costs are lower simply because the induction bending. No sand filling needed. No internal mandrel. The whole equipment set-up is smaller and cheaper.

Although more cost-effective, induction bending does deliver a final product that is superior in at least three ways:

- smoother finish
- fewer imperfections
- minimal distortions

Induction bending leaves no joints to weld together. Fewer joints not only means a stronger product than if it has been hot rolled, but also a smoother finish.

Cold rolling isn’t perfect. “Wall thinning” and warping are among the imperfections that can happen, in part due to the thinner nature of the metal used. Induction bending tends to create a more even and predictable quality than cold rolling.

And induction bending created the fewest distortions in the metal, for one very obvious reason - most of the metal is not touched. Since heat is very localized and bending is equally localized, the integrity of the rest of the pipe remains intact.

It should be noted that these methods of bending and forming metal are not mutually exclusive. For instance, hot rolled steel often ends up as coiled sheet metal. This sheet metal ifs often then fed through the cold rolling steel process, where it becomes thinner sheet metal, metal foil and metal plates.

So it is not always just a choice between induction bending, hot rolling and cold rolling that needs to be made. Sometimes it is a decision of just exactly how to best combine two of the methods for the highest quality result, meeting the specifications of the client while minimizing possible weaknesses and imperfection, all the while keeping costs as low as possible. This is not a simple task.