Bending Sheet Metal Bend Allowance

Mathematically k factor value is equal to the ratio of position of neutral axis and sheet thickness.

Bending sheet metal bend allowance. ß bending angle for bends between 90 and 165 degrees the formula is. Radius metal will crack at the outside heel of the bend. Radius of a bend is determined by the hardness and thickness of the metal. A line through the thickness of the bend called the neutral axis does not change in length when the part is bent.

Bend allowance is used to account for bends in sheet metal fabrications. The bend allowance and bend deduction are two measures that relate the bent length of a piece of sheet metal to the flat length. Therefore the bend allowance added to the flange lengths is equal to the total flat length. For bends between 0 and 90 degrees the formula is as follows.

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 material thickness will be measured in decimal form not by the gauge number. The bend allowance region is shown in green in my diagram this is a region wherein theory all deformation occurs during the bending process. Sheet metal calculator bend allowance equations and calculator.

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. Most sheet metal materials will conform to the calculations. Bend allowance is the amount of metal to be added to the total layout. 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.

You will need to know your material thickness mt the bend angle b the inside radius ir and the k factor k. The most important considerations when bending metal is the min. This page also includes a link to a on line sheet metal bend allowance calculator. 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.

The bend allowance describes the length of the neutral axis between the bend lines or in other words the arc length of the bend.