A review of Metal Bending Techniques

The progression of metal bending technology over the last century has allowed manufacturing companies to push the boundaries of curving steel to a new high. The bending process has advanced from basic press bending to innovative induction bending.

The options for bending material are greater than ever before, although many of the methods overlap in capacity, each of the methods offer unique qualities that customers will have to evaluate. When deciding on a bending technique, some of the main factors to take account of are the quantity and the quality required.

Press Bending: Although press bending is the eldest of bending methods, it is still used for a variety of jobs today. This method of bending is executed by two tools holding the material in place as a third tool applies pressure to the material. After many hits/rams to the material it can be crafted to various radii. This process can lead to a substantial amount of distortion, especially on tighter radii.

Rotary Draw Bending: Rotary draw bending is a process that is executed by wrapping material around a die. The limitations of this process surface with the need for manufacturers to have a plethora of dies.  In order to bend 1 inch and 2 inch pipe to both 3 inch and 6 inch radius, you must have a separate die for each pipe/radius combination. Companies with an extensive collection of dies are able to fabricate material into a wide range of radii. With rotary draw bending, beware of ovality when bending tubes with thin walls.  Most fabricators will suggest thicker walled pipe when using this technique.

Mandrel Bending: Mandrel Bending is closely related to rotary draw bending. This technique involves stuffing pieces with hardened steel to prevent distortion. Understandably this process is only done with hollow pieces, particularly rectangular tube and thin wall pipe, which have the tendency to collapse.

Three-Roller Bending: Three roll bending is a technique that allows for an endless range of radii. This technique engages three rollers to form the material.  One center roll is used as a fulcrum, with the material passing between this roll and the paired back rollers.  Depending on the type of three roll bender being used, either the center/front roller or the two back rollers will move to increase the pressure on the material, thus tightening the radii of the roll.

Induction Bending: Induction Bending is one of the hottest styles of bending in 2015, quite literally. Induction bending involves heating one point of the material using an induction coil.  The material is then molded by a pivot arm to the preferred radii. Induction bending is time consuming but it does produce low-distortion bends in material that standard cold bending would deform.

Each of these bending techniques comes with Pro’s and Con’s and it is beneficial to become educated on each so you can pick the right style for your next bend.


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