Bend Deduction Formula Sheet Metal Bending

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

Bend deduction formula sheet metal bending.

The material thickness will be measured in decimal form not by the gauge number. Bend allowance bend deduction 2 ossb. As explained in my first post the bend deduction can be calculated using the following equation. The mold line lengths are the distances measured to the outside mold line and are equal to the flange lengths plus the setback.

You will need to know your material thickness mt the bend angle b the inside radius ir and the k factor k. Refer to the chart for values for folder as well as various press brake tooling combinations. Cells on the right will output the desired values. The formula is as follows.

Geometry of tooling imposes a minimum bend dimension. This page also includes a link to a on line sheet metal bend allowance calculator. You only have to insert interior angle flange lengths k factor inside radius and material thickness. The material thickness will be measured in decimal form not by the gauge number.

In machinery s handbook the k factor for mild cold rolled steel with 60 000 psi tensile strength is 0 446 inch. Therefore the bend deduction equals the difference between the mold line lengths and the total flat length. Another method that solidworks uses is the bend deduction method. As with bend allowance bend deduction comes from the same sources tables and manual testing.

The diagram shows one such mechanism. Bd bend deduction. Use the minimum bend dimension values in the charts below for your minimum closeness of cutout to a bend. Ossb is defined as illustrated in figure 5 for different bending angles and can be calculated using the equation below.

Learn more about bending. The following illustration shows the equation calculation for determining the bend allowance when forming sheet metal. Ba 0 017453 inside radius 0 0078 material thickness bend angle which is always complementary the length of the neutral axis is calculated as a bend allowance taken at 50 percent of the material thickness. The flatten length of the parts that are lf equals d1 plus d2 minus the bend deduction.

Most sheet metal materials will conform to the calculations. Calculate the value of bend deduction from the values of bend allowance and outside setback. Calculate the value bend allowance for required sheet metal bend by using below formula. Where ossb is the outside setback.

Lf d1 d2 bd. Where a is the bending angle t is the sheet thickness and r is the bending radius. The values of the setback bend allowance and bend deduction can be calculated from the sheet thickness bend radius bend angle and k factor. With this free online tool we quickly get the sheet metal bend deduction and therefore the sheet metal blank initial flat length from the finished part measurements.

Sheet metal calculator bend allowance equations and calculator.