Dimensioning Sheet Metal Bends

Bends in sheet metal are manufactured using sheet metal brakes.

Dimensioning sheet metal bends.

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. A 1 degree tolerance on all bend angles. Bend angle 1 degree. Sheet metal parts with a minimum of 0 9mm to 20mm in thickness can be manufactured.

D 2 5t r see below the height can be less but it required secondary operations and is far more costly. Bend length 0 010 0 25mm. The diagram shows one such mechanism. It shall be equal to three times of sheet thickness plus bend radius.

5 edge distortion an exaggerated example of edge deformation is pictured in figure a below. No worries of forgetting a material thickness along the way 3. Bends specified as angles may be toleranced at plus or minus one half. As one who daily works with sheet metal design and fabrication use outside flange lengths for several reasons.

Minimum sheet metal flange bend length 3 x sheet thickness bend radius. Form height to thickness ratio to determine the minimum form height for sheet metal use the following formula. This is a common occurrence when manufacturers receive a sheet metal layout dimensioned in the flat pattern. When you figure flat pattern length you simple add up all the outside flanges and subtract the bend deductions.

The basics of applying bend functions the fabricator november 2012 by steve benson explains it in detail. Folder 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.

In low carbon steel sheet metal the minimum radius of a bend should be one half the material thickness or 0 80 mm 0 03 inch whichever is larger. 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 is required to avoid cracks in the bending area. Bends on the same plane should occur in the same direction.

Figure 3 because the bend line shifts after forming the edge to inside surface dimension will be greater than the edge to bend line dimension. Press brake bend length 0 010 0 25mm per bend for controlled dimension. Avoid large sheet metal parts with small bent flanges. 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.