Bend Allowance Formula In Sheet Metal

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.

Bend allowance formula in sheet metal.

Sheet metal calculator bend allowance equations and calculator. Therefore the bend allowance added to the flange lengths is equal to the total flat. We are going to review three bending scenarios with three different bending angles. Most sheet metal materials will conform to the calculations.

Sheet metal flat length can be calculated in the following three simple steps. In the example above it is indicated by a dashed blue line. Bend allowance ba π 180 r k t a. There is sheet metal software available that performs all calculations automatically like solidworks and litio.

The following illustration shows the equation calculation for determining the bend allowance when forming sheet metal. Although it is an option for calculating a bend in some cad programs such as solid works it is not often referred to in the actual manufacturing process since. Consider a sheet with a 20 mm thickness and a length of 300 mm as shown in figure 1. But the most accurate way to find out k factor is reverse engineering of a small but same sheet metal sample piece.

Procedure is as below. This page also includes a link to a on line sheet metal bend allowance calculator. 60 90 and 120 and we will calculate k factor bend allowance and bend deduction for them. The bend allowance and bend deduction are two measures that relate the bent length of a piece of sheet metal to the flat length.

The bend allowance is the amount of the neutral axis that bends. In the example above it is indicated by a dashed blue line. When the sheet metal is put through the process of bending the metal around the bend is deformed and stretched. Bend allowance is a measure of how much extra material is required to accommodate a bend in sheet metal this is a function of the bend angle bend radius thickness of the material and a variable called the k factor bend allowances vary based on the angle of the bend the type and thickness of the material and the method used to create the bend.

The bend allowance ba is the length of the arc of the neutral line between the tangent points of a bend in any material. The bend allowance method is based on the formula that i ve got appear in my diagram. Lf l1 l2 ba. The bend allowance describes the length of the neutral axis between the bend lines or in other words the arc length of the bend.

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. There are standard charts available with sheet metal design handbook for calculating k factor ideally it should be 0 5. So if you got k factor value now you can easily calculate bending allowance. Ba bend allowance.