Bending Sheet Metal Bend Allowance

The material thickness will be measured in decimal form not by the gauge number.

Bending sheet metal bend allowance.

For bends between 0 and 90 degrees the formula is as follows. You will need to know your material thickness mt the bend angle b the inside radius ir and the k factor k. Bend allowance is the amount of metal to be added to the total layout. Mathematically k factor value is equal to the ratio of position of neutral axis and sheet thickness.

Bend allowance is used to account for bends in sheet metal fabrications. Sheet metal calculator bend allowance equations and calculator. 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 following illustration shows the equation calculation for determining the bend allowance when forming sheet metal.

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. 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. Most sheet metal materials will conform to the calculations. A line through the thickness of the bend called the neutral axis does not change in length when the part is bent.

This page also includes a link to a on line sheet metal bend allowance calculator. The bend allowance region is shown in green in my diagram this is a region wherein theory all deformation occurs during the bending process. ß bending angle for bends between 90 and 165 degrees the formula is. When bends are made smaller than the required min.

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. The bend allowance formula takes into account the geometries of bending and the properties of your metal to determine the bend allowance. Radius of a bend is determined by the hardness and thickness of the metal. Radius metal will crack at the outside heel of the bend.

Therefore the bend allowance added to the flange lengths is equal to the total flat length.