Bending Sheet Metal Into A Box

Box bending can be rather tricky with sheet metal because of the geometry of a press brake.

Bending sheet metal into a box.

Lower the clamping bar handle down to clamp your metal into place. Not everything requires a 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. 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.

Springback is defined as a material s natural tendency to return to its unbent position. 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. Sheet metal bending should be as perpendicular as possible to the direction of the metal fiber. A flat version of your box.

Return your bending leaf to neutral position and lift up your teeth to remove your bent metal. Use the corner notcher to cut out any right angles. Typically the upper beam or punch holder will get in the way of very deep boxes. Slide your metal piece underneath the teeth and line your marked line up with the edge of the teeth.

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. You can find your bend allowance with the following formula. 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. 1 first you want to make an expanded template for your box out of cardboard paper etc.

Use your bending leaf handles to slowly fold your sides and tabs to 90 degrees. There are lots of other ways to bend sheet metal especially if it s a smaller piece.