Let’s talk about hot rolling.

We should begin be defining four important terms:

- Hot rolling
- Cold rolling
- Induction bending
- Induction coils

HOT ROLLING: Hot rolling is the process of heating a large tract of steel (rarely any other type of metal) and using weighted rollers to shape the metal, typically to make it thinner. The heat is fairly substantial, between 800 and 2,200 degrees Fahrenheit. The rollers are calibrated to place just the right amount of pressure on the steel to meet the thickness and other specifications of the client.

COLD ROLLING: Cold rolling differs from hot rolling, primarily because it doesn’t use heat. Yes, that is obvious. But the heat is needed for bulkier and less-finished material. Cold rolling would more typically be used on sheet metal, steel rods, bars and the like. Cold rolling’s main advantage is that the metal retains its strength more than hot rolling does.

INDUCTION BENDING: Induction bending is a totally different process with a totally different purpose. It is used to bend almost any metal, but typically pipe and tube forms. It is a highly energy-efficient process, because only a small section needs to be heated - just the section that requires a bend. So a long pipe that would typically remain straight, such as a petroleum or natural gas pipelinet, needs to be heated only at those select points that require a bend.

INDUCTION COILS: These are coils used to heat through a process called “induction”. Really they are transformers that convert DC power into very high heat. It consists of two insulated copper wires coiled around an iron core. A vibrating interrupter creates a faster pulse from the low-voltage DC power, creating a higher voltage pulse for more heat. Induction coils are used to heat the tubes and pipes in 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 metal rolling company would prefer induction bending over other methods when it is appropriate for the job:

A) Induction bending creates minimal distortion in the tube or pipe, because only a small section of the metal tube or pipe is heated. The rest of the pipe remains untouched and unaffected.

B) Induction bending is more energy-efficient than hot rolling (although not more than cold rolling) because only a small section of the metal tube requires heat. This saves on costs and is better for the environment,

C) Induction bending does not require any sand filling or internal mandrels. This greatly reduces overhead costs of operations (less equipment!).

D) Induction bending is relatively quick, consuming less time, which also keeps labour costs down significantly.

E) Induction bending tends to deliver a higher quality product than cold bending does. Often cold bending can lead to excessive warping and wall thinning. It is important for the steel bending company to know the limits and capabilities of its machines and of the processes involved in each method of bending metal.

F) Induction bending eliminates the need for mechanical or welded joints. What this means for the finished product is that it sports a smoother finish.

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.