Bend Allowance Table For Sheet Metal

Table 1 preferred recommended 90 degree bend radii for various sheet metals.

Bend allowance table for sheet metal.

To use the tables below. 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 material thickness will be measured in decimal form not by the gauge number. Therefore even a simple bench with enough room to bend 3 m pieces will do the job.

After bending the sheet we need to do some measurements as shown in figure 2. Therefore the bend allowance added to the flange lengths is equal to the total flat length. The required die width is 12 mm and tonnage per meter is 22. L unfold length a outside size b outside size k k factor none 90 bend unfold according to the neutral layer the distance from neutral to sheet inner side is t 3 inner r can refer to the above chart.

Figure 2 illustrates the sheet that is bent with the bend angle of 90 degrees. The lowest common bench capacity is around 100 tonnes. From there we can calculate the k factor and the bend deduction. The bend allowance and bend deduction are two measures that relate the bent length of a piece of sheet metal to the flat length.

You will need to know your material thickness mt the bend angle b the inside radius ir and the k factor k. The bend allowance formula takes into account the geometries of bending and the properties of your metal to determine the bend allowance. My workpiece s bending line is 3 m so the overall needed force is 3 22 66 tonnes. We will start by calculating the bend allowance.

The tables below show bend radii and minimum bend sizes for materials and tooling combinations stocked by protocase. When the sheet metal is put through the process of bending the metal around the bend is deformed and stretched. Understanding the bend deduction and consequently the bend allowance of a part is a crucial first step to understanding how sheet metal parts are fabricated. The following illustration shows the equation calculation for determining the bend allowance when forming sheet metal.

This page also includes a link to a on line sheet metal bend allowance calculator. Bend forming 0 l a b 0 43t t thickness deduction 0 43t. Calculate unfold size with bend allowance chart. Most sheet metal materials will conform to the calculations.