Dimensioning Sheet Metal Bends

Minimum sheet metal flange bend length is required to avoid cracks in the bending area.

Dimensioning sheet metal bends.

Use the minimum bend dimension values in the charts below for your minimum closeness of cutout to a bend. Minimum sheet metal flange bend length 3 x sheet thickness bend radius. Bends in sheet metal are manufactured using sheet metal brakes. Avoid large sheet metal parts with small bent flanges.

When you figure flat pattern length you simple add up all the outside flanges and subtract the bend deductions. Bend length 0 010 0 25mm. Bend angle 1 degree. The basics of applying bend functions the fabricator november 2012 by steve benson explains it in detail.

Form height to thickness ratio to determine the minimum form height for sheet metal use the following formula. These dimensions may seem helpful but after your manufacturer makes bend deductions based on their capabilities and other bending factors your dimensions will become unusable. Bends specified as angles may be toleranced at plus or minus one half. When designing parts for laser cutting one should not make holes smaller than the thickness of the material.

As one who daily works with sheet metal design and fabrication use outside flange lengths for several reasons. D 2 5t r see below the height can be less but it required secondary operations and is far more costly. Geometry of tooling imposes a minimum bend dimension. The best way to measure a hem from the outside radius to the hem edge is with a surface plate angle block and a height gauge.

A 1 degree tolerance on all bend angles. 5 edge distortion an exaggerated example of edge deformation is pictured in figure a below. It shall be equal to three times of sheet thickness plus bend radius. Bends on the same plane should occur in the same direction.

Folder bend length 0 010 0 25mm per bend for controlled dimension. Sheet metal stretches when it bends is an oversimplification. No worries of forgetting a material thickness along the way 3. This is a common occurrence when manufacturers receive a sheet metal layout dimensioned in the flat pattern.

Sheet metal parts with a minimum of 0 9mm to 20mm in thickness can be manufactured. Press brake bend length 0 010 0 25mm per bend for controlled dimension. Upon close examination of the bends we find that the sheet metal stretches on the outer surface and that the inside surface seems to shrink. Refer to the chart for values for folder as well as various press brake tooling combinations.