Updated by Bend-It on September 14, 2015
Cold bending is a continuous bending process in which the desired strip of metal is passed through successive sets of rollers that incrementally bend the metal to its desired cross-section profile. Cold bending is the preferred choice for producing segments and parts with longer lengths and in large bulk quantities. It's also generally the least costly process of all metal forming processes, including hot bending, induction bending, and rotary-draw bending.
Unlike cold bending, hot bending occurs when the desired metal part is heated directly to 'soften' it and then its bend. Heat sources used for this bending process range from applying a direct flame to putting the metal into a furnace. Heat bending is most generally used in repairs when a fault or crack has already occurred to the metal. This is because for many metals, the heating process can weaken and stress the metal.
Cold bending is the ideal choice with most non-ferrous metals that don't contain much iron, and it's a top choice when rolling long strips of steel. Before you decide whether you should request cold rolling or hot rolling, have answers to the following questions ready: What alloy is the steel? What's the wall thickness? The desired radius of bend? In most cases, cold rolling will be the preferred choice, but it's important to speak with an expert about the specifics of any job.
Updated by Bend-It on August 26th, 2015
Structures come in a variety of different shapes and sizes, and they are categorized by sections within groups starting from small to large. Parts of these structures can form angles, I-beams, T-beams, square or various forms of tubing, solid bars as well as many other structural components. When it comes to structural architecture, there are two primary methods in bending: hot and cold.
Structural architecture falls into one of two categories--load-bearing or architectural. Looking at both of these two categories the most important part of this is product quality. Bend and material quality are the principal factors for a load-bearing structure, whereas physical appearance is the most important in architectural designs. Load-bearing applications have wide beams that are typically used in overpasses, whereas shaped applications are found in building entrances, road tunnels, and sculptures.
Both applications have challenges when it comes to structural materials. When creating angles, T- and I-beams, the challenge begins with radius. If the radius becomes too tight, it will deform and can get to a critical point. This is where the differences in hot- and cold-bending come into play.
Using the Cold
Large-radius bends are usually done with cold-roll material, depending on the type of equipment you use and the thickness of the material. When it comes to large-radius bends, cold-rolling will achieve the desired radius.
Using the Heat
When you are on the job, you may find it easier to bend a particular section by means of using heat. The type of material and its configuration will determine whether or not it is suitable for bending with heat.
When it comes to using heat in bending, a particular coil can be built to exact specifications. A heated area can be controlled so that the heated coil induces a narrow band of heat into the workplace. The heated bending area is the only portion of the material that will bend, and when the bend is complete, the area is rapidly cooled with water.