Bend Allowance Formula In Sheet Metal

The following illustration shows the equation calculation for determining the bend allowance when forming sheet metal.

Bend allowance formula in sheet metal.

Therefore the bend allowance added to the flange lengths is equal to the total flat. The bend allowance is the amount of the neutral axis that bends. Childress last modified date. Sheet metal calculator bend allowance equations and calculator.

Adding the length of each flange taken between the center of the radius to the ba gives the. 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. It is better to solve some formula based examples to really understand the fabrication formulas for sheet metal bend allowance ba the amount of material added to the sum of the two leg lengths to obtain the flat pattern 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.

Consider a sheet with a 20 mm thickness and a length of 300 mm as shown in figure 1. 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.

August 29 2020. 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. You will need to know your material thickness mt the bend angle b the inside radius ir and the k factor k.

This page also includes a link to a on line sheet metal bend allowance calculator. In the example above it is indicated by a dashed blue line. The bend allowance ba is the length of the arc of the neutral line between the tangent points of a bend in any material. Where ba is bending allowance.

If you have a sheet metal bending product as shown in above picture with two legs of length x and y and you unbend it you will see that total length of the unbend sheet will not x y rather the length will be x y ba. There is sheet metal software available that performs all calculations automatically like solidworks and litio. Ba bend allowance. In the example above it is indicated by a dashed blue line.

Most sheet metal materials will conform to the calculations. The bend allowance formula takes into account the geometries of bending and the properties of your metal to determine the bend allowance.