Bending Sheet Metal Into A Box

Not everything requires a brake.

Bending sheet metal into a box.

When bending a 2 sided box with only a bottom front and back it is possible to remove a section of the holder and let the punch for a bridge. Typically the upper beam or punch holder will get in the way of very deep boxes. Sheet metal bending should be as perpendicular as possible to the direction of the metal fiber. Besides the usual springback considerations for a normal bend the width of the ram needs to be taken into account with deep box forming to find the true minimum.

When the sheet metal bend is parallel to the direction of the fiber of the metal material cracks are likely to occur at the bend of the sheet metal and the bending strength is low and it is easy to break as shown in the following figure. Use your bending leaf handles to slowly fold your sides and tabs to 90 degrees. One way that i often work with sheet metal for automotive panels is to sandwich 2 4 s in a vise with the workpiece in the middle then work the metal with a rubber mallet. Use the corner notcher to cut out any right angles.

1 first you want to make an expanded template for your box out of cardboard paper etc. I have a graph paper drawing in the pics below but its not for this box 2 trace your template on to your piece of sheet metal as pictured i suggest 20 22 gauge steel 3 cut your piece into the same shape as template. A flat version of your box. When bending with large returns there are a few tricks outside of just tooling selection.

Box bending can be rather tricky with sheet metal because of the geometry of a press brake. π 180 x b x ir k x mt bend allowance ba where b is the angle complementary to your desired bend angle 1 to 180 degrees mt is the thickness of the material ir is the inside radius and k is the k factor. You can find your bend allowance with the following formula. Lower the clamping bar handle down to clamp your metal into place.

There are lots of other ways to bend sheet metal especially if it s a smaller piece. This is caused by the tension between the material s expansion on the outside of the radius and the compression on the inside see figure 4.