Bend Deduction Sheet Metal

Understanding the bend allowance and consequently the bend deduction of a part is a crucial first step to understanding how sheet metal parts are fabricated.

Bend deduction sheet metal.

Should be subtracted from the flat pattern so the formed part arrives at the desired dimensions. Cells on the right will output the desired values. The u punch forms a u shape with a single punch. This is simulated on the part shown above by the section shown in red.

When the sheet metal is put through the process of bending the metal around the bend is deformed and stretched. The formed bend radius is dependent upon the dies used the material properties and the material thickness. As this happens you gain a small amount of total length in your part. The bend deduction formula takes into account the geometries of bending and the properties of your metal to determine the bend deduction.

The material thickness will be measured in decimal form not by the gauge number. You only have to insert interior angle flange lengths k factor inside radius and material thickness. You will need to know your material thickness mt the bend angle b the inside radius ir and the k factor k. The bend deduction of means that the material is expected to stretch by that amount during the course of bending.

The bend radius refers to the inside radius. Bend deductions are the first and more critical aspects when working with fabricated sheet metal. If missed it will wreak havoc on your formed parts done well and you ll have a precise measurement you and your clients will be happy with.