Sheet Metal Bend Relief Formula

In general a minimum bend relief is equal to the material thickness plus the inside bend radius.

Sheet metal bend relief formula.

The bend allowance formula takes into account the geometries of bending and the properties of your metal to determine the bend allowance. The diagram shows one such mechanism. Refer to the chart for values for folder as well as various press brake tooling combinations. Sheet metal calculator bend allowance equations and calculator.

Use the minimum bend dimension values in the charts below for your minimum closeness of cutout to a bend. This page also includes a link to a on line sheet metal bend allowance calculator. 5 edge distortion an exaggerated example of edge deformation is pictured in figure a below. ß bending angle for bends between 90 and 165 degrees the formula is.

Geometry of tooling imposes a minimum bend dimension. The bend deduction sometimes called the bend compensation describes how much the outside of the sheet has been stretched. When sheet metal makes a transition from a bend to a flat surface or to another bend it tends to rip and tear. Therefore the bend allowance added to the flange lengths is equal to the total flat length.

The material thickness will be measured in decimal form not by the gauge number. You will need to know your material thickness mt the bend angle b the inside radius ir and the k factor k. The following illustration shows the equation calculation for determining the bend allowance when forming sheet metal. To eliminate this a bend relief is added so the edge of the sheet metal is perpendicular to the bend.

For bends over 165 there is no need to calculate bend allowances as the neutral axis stays pretty much in the middle of the detail. We are going to review three bending scenarios with three different bending angles. Most sheet metal materials will conform to the calculations. Consider a sheet with a 20 mm thickness and a length of 300 mm as shown in figure 1.

D 2 5t r see below the height can be less but it required secondary operations and is far more costly. For bends between 0 and 90 degrees the formula is as follows.