Bending Sheet Metal Bend Allowance

A line through the thickness of the bend called the neutral axis does not change in length when the part is bent.

Bending sheet metal 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. The most important considerations when bending metal is the min. Radius metal will crack at the outside heel of the bend.

Sheet metal calculator bend allowance equations and calculator. When a piece of sheet metal is bent the overall length of the piece changes because of compression on the inside of the bend and tension on the outside. The bend allowance region is shown in green in my diagram this is a region wherein theory all deformation occurs during the bending process. For bends between 0 and 90 degrees the formula is as follows.

The material thickness will be measured in decimal form not by the gauge number. Bend allowance is used to account for bends in sheet metal fabrications. ß bending angle for bends between 90 and 165 degrees the formula is. 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.

When bends are made smaller than the required min. Sheet metal k factor bend allowance and flat length calculations k factor in sheet metal bending is a constant used to calculate sheet metal flat length or flat pattern. Most sheet metal materials will conform to the calculations. The following illustration shows the equation calculation for determining the bend allowance when forming sheet metal.

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 bend allowance and bend deduction are two measures that relate the bent length of a piece of sheet metal to the flat length. 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. Therefore the bend allowance added to the flange lengths is equal to the total flat length.

The bend allowance formula takes into account the geometries of bending and the properties of your metal to determine the bend allowance.