In most circumstances, metal that is used for pipe fabrication needs to be heated before it can be bent into shape.
However, there are some instances when heating metal isn’t an option. Some metals can be bent cold if the right process is used. It isn’t recommended for certain metals such as brass as it can cause them to crack or even shatter.
In addition, it isn’t recommended for smaller bends since it can cause smaller bends to kink. Most of the time, cold bending is used for pipes or tubes that require larger bends.
Cold Bending Process
The process of cold bending steel is actually performed at what is considered room temperature.
It is referred to as cold bending to differentiate the process from hot bending in which steel is heated by a torch or furnace before shaping.
Cold bending process is generally performed using rollers to press a piece of steel against metal shaping tools called dies.
It may also be referred to as cold rolling or pyramid rolling.
Benefits of Cold Bending
Cold bending does not require the use of fuel to heat the steel before processing, and the additional time and effort of heating and then cooling the steel are eliminated.
Cold rolling results in a smoother, more finished surface and generally causes less deformation of the item being processed.
One additional benefit is the increased strength imparted by working the steel while cold. When steel is manufactured at high heat and then allowed to cool it develops an internal crystalline arrangement. Working steel at ambient temperatures below the point of crystallization has been shown to enhance strength at a molecular level by compressing and distorting the crystalline structure. As the molecules become compacted they are unable to move as easily and, therefore, the steel becomes stronger. Working steel at high heat above the point of crystallization means that crystallization will occur after the steel has been worked and therefore the steel will not be any stronger than unworked steel. Heating steel that has already been cold bent or rolled will cause the material to lose the extra strengthening gained from the process by allowing the steel to regain its internal crystalline structure.
The trade-off between cold and hot working processes is that in exchange for the added strength of cold working the steel can become more brittle, while heat worked steel generally retains greater ductility.
Cold bending is also known as roll bending because of the process most commonly used to bend metal that hasn’t been heated.
Roll bending is accomplished using a mechanical jig that uses three rollers to bend metal into a circular arc.
The two outer rollers are usually immobile and are used to hold the metal in place, while the third roller places pressure on top of the metal, creating the large bend that is needed for the project.
The process is particularly useful when bending sheet metal. Bending pipes and tubes in this way is more difficult, but it can be done.
When you need to bend various types of metal profiles, cold bending has many advantages over hot bending.
Why choose cold bending?
With cold bending service, you will be able to use a variety of metal alloys.
Because hot bending will expose the profile to high temperatures, the performance of many metals will be destroyed or greatly weakened. No matter what metal you use, you can’t risk weakening the metal’s properties.
Therefore, the cold bending method will be your best choice.
In the case of metals approaching or immersed in water, salinity must be considered. Some metals can withstand higher salinity levels, which ultimately allows you to choose metals that can be retained for longer periods of time.
If you need to bend metal immersed in water, cold bending may be the only option you consider.
Cold-bending spiral coil
The same is true for spiral coils. When some coils are exposed to heat, other coils are designed for pressure or other purposes. You cannot risk bending and destroying the structural integrity of the metal due to heating. After using the heat for a long time, cracks in the metal will form, which may cause accidents on site. Even a small leak can cost you a lot of money, and accidents can cause injuries to employees.
There are many benefits of cold bending, which you can use in your operation. You cannot take the risk of weak metal or leakage.
Types of Cold Bending and Custom Metal Bending Products:
Cold Bending for Different Steel Configurations
Any cross-section and size of steel can be cold bent or rolled as long as it can fit into existing dies and rollers. Cold bending is most commonly applied to pipes of less than 10 inches diameter, channels, I-beams, angles and rectangular, round and half-round bars. Large scale steel products such as plates can also be worked but sizes are limited due to the force necessary and the size of the rolling equipment needed. The bending process can be used to create gentle, large-diameter curves, 90ｰ corners or long series of pipe coils in which the pipe bends in a succession of 360ｰ circular turns.
Uses for Steel Shaped by Cold Bending
Cold bent steel has many uses. Curved steel formed by cold bending is frequently used in the construction of buildings and bridges and is especially impressive when left exposed to view. Shipbuilders, railroads and automobile manufacturers also use cold bent steel products. The petrochemical industry uses curved and coiled piping for processing and transporting their products. Cold bent steel also has many other industrial and food-processing uses as well.
Cold bending is an excellent way to shape steel with minimal deformation during the bending process. Steel shaped by cold bending can be found in applications ranging from commonly used everyday items to highly technical specialized industrial applications.
Offer the best solution to cooling and heating applications using rinse tanks, acid solutions, alkaline mixes and replacement heating elements.
Perfect for supporting blind flanges used in the openings of pressure vessels. Additionally, they can be used to hold an item up while workers are moving another item product place.
Special ordered cold bending is important to the aerospace and petrochemical industries as well as oil fields and refineries. Pipe bending orders can be carried out in every type of custom shape for diversified uses including angle rolling, channel rolling, I-beam rolling and flat bar bending.
Rolled pipes can include an arc, curve or particular radius. Custom bending creates arcs from 1 – 360 degrees or industry standards including 2D, 3D or 5D bends.
Serpentine Coils – Fills an industry need for cooling and heating applications that require a medium transfer of heat, rather than a large amount. They are constructed using up to eight vertical lengths of tubing spaced around the perimeter of a vessel.
Using specific die sets and a centerline radius, rotary draw bending is a very precise method of bending.
Related reading:Section 4 understands the cold bending process of metal profiles