Sheet Metal Bend Relief Formula

60 90 and 120 and we will calculate k factor bend allowance and bend deduction for them.

Sheet metal bend relief formula.

When sheet metal makes a transition from a bend to a flat surface or to another bend it tends to rip and tear. ß bending angle for bends between 90 and 165 degrees the formula is. To eliminate this a bend relief is added so the edge of the sheet metal is perpendicular to the bend. Form height to thickness ratio to determine the minimum form height for sheet metal use the following formula.

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. D 2 5t r see below the height can be less but it required secondary operations and is far more costly. The diagram shows one such mechanism. This page also includes a link to a on line sheet metal bend allowance calculator.

For bends between 0 and 90 degrees the formula is as follows. Use the minimum bend dimension values in the charts below for your minimum closeness of cutout to a bend. The material thickness will be measured in decimal form not by the gauge number. Geometry of tooling imposes a minimum bend dimension.

In general a minimum bend relief is equal to the material thickness plus the inside bend radius. 5 edge distortion an exaggerated example of edge deformation is pictured in figure a below. You will need to know your material thickness mt the bend angle b the inside radius ir and the k factor k. Therefore the bend allowance added to the flange lengths is equal to the total flat length.

Refer to the chart for values for folder as well as various press brake tooling combinations. Consider a sheet with a 20 mm thickness and a length of 300 mm as shown in figure 1. Most sheet metal materials will conform to the calculations. The bend deduction sometimes called the bend compensation describes how much the outside of the sheet has been stretched.

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