Bending Allowance Formula For Sheet Metal

Bending is one of the most common sheet metal fabrication operations.

Bending allowance formula for sheet metal.

In the example above it is indicated by a dashed blue line. Also known as press braking flanging die bending folding and edging this method is used to deform a material to an angular shape. So if you got k factor value now you can easily calculate bending allowance. The bend allowance and bend deduction are two measures that relate the bent length of a piece of sheet metal to the flat length.

We are going to review three bending scenarios with three different bending angles. Consider a sheet with a 20 mm thickness and a length of 300 mm as shown in figure 1. Commonly used equipment include box and pan brakes brake presses and other specialized machine presses typical products that are made like this are boxes such as electrical enclosures and rectangular ductwork. There are standard charts available with sheet metal design handbook for calculating k factor ideally it should be 0 5.

The total length of the flatten sheet is equal to the sum of l1 that s the first length and l2 plus the bend allowance. The bend allowance is the amount of the neutral axis that bends. Bending is a manufacturing process that produces a v shape u shape or channel shape along a straight axis in ductile materials most commonly sheet metal. Sheet metal calculator bend allowance equations and calculator.

The following illustration shows the equation calculation for determining the bend allowance when forming sheet metal. But the most accurate way to find out k factor is reverse engineering of a small but same sheet metal sample piece. This page also includes a link to a on line sheet metal bend allowance calculator. This is done through the application of force on a workpiece.

The bend allowance describes the length of the neutral axis between the bend lines or in other words the arc length of the bend. Most sheet metal materials will conform to the calculations. When the sheet metal is put through the process of bending the metal around the bend is deformed and stretched. Procedure is as below.

If the value of sheet metal k factor and bending flange length is known. Ba bend allowance. Bend allowance ba π 180 r k t a. In the example above it is indicated by a dashed blue line.

60 90 and 120 and we will calculate k factor bend allowance and bend deduction for them. Calculate the value bend allowance for required sheet metal bend by using below formula. The bend allowance region is shown in green in my diagram this is a region wherein theory all deformation occurs during the bending process. The force must exceed the material s yield strength to achieve a plastic deformation.

Understanding the bend allowance and consequently the bend deduction of a part is a crucial first step to understanding how sheet metal parts are fabricated.