Bending Sheet Metal Bend Allowance

The bend radius refers to the inside radius.

Bending sheet metal bend allowance.

Radius of a bend is determined by the hardness and thickness of the metal. Bend allowance is a measure of how much extra material is required to accommodate a bend in sheet metal. This page also includes a link to a on line sheet metal bend allowance calculator. Also known as press braking flanging die bending folding and edging this method is used to deform a material to an angular shape.

Most sheet metal materials will conform to the calculations. Cells on the right will output the desired values. We will start by calculating the bend allowance. Sheet metal calculator bend allowance equations and calculator.

The following illustration shows the equation calculation for determining the bend allowance when forming sheet metal. The bend allowance formula takes into account the geometries of bending and the properties of your metal to determine the bend allowance. The material thickness will be measured in decimal form not by the gauge number. 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.

This is a function of the bend angle bend radius thickness of the material and a variable called the k factor. The bend allowance describes the length of the neutral axis between the bend lines or in other words the arc length of the bend. This is done through the application of force on a workpiece. You will need to know your material thickness mt the bend angle b the inside radius ir and the k factor k.

From there we can calculate the k factor and the bend deduction. 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. When sheet metal is bent it stretches in length.

The bend allowance and bend deduction are two measures that relate the bent length of a piece of sheet metal to the flat length. Figure 2 illustrates the sheet that is bent with the bend angle of 90 degrees. When bends are made smaller than the required min. With this free online tool we quickly get the sheet metal bend deduction and therefore the sheet metal blank initial flat length from the finished part measurements.

Bend allowance is the amount of metal to be added to the total layout. The bend deduction is the amount the sheet metal will stretch when bent as measured from the outside edges of the bend. Bending is one of the most common sheet metal fabrication operations. After bending the sheet we need to do some measurements as shown in figure 2.

Radius metal will crack at the outside heel of the bend. 90 degrees bend angle.