Press brakes are used to accurately press and bend sheet and plate material. They consist of a punch and die. The die is usually in the form of a V-block which the plate or sheet is placed on top of. The punch in the form of a blade is then pressed down onto the material which then forms the required bend.
The position of the bend is controlled by a backstop and the angle of the bend is determined by how far the blade is lowered into the V-block.
The internal radius of the bend is limited by the material thickness. If the radius is too tight, the material may crack and split. In general, the internal radius of a bend should be no smaller than the material thickness. The bend radius is controlled by the press tooling. Smaller dies and sharper punches can be used for thinner material. Thicker material requires larger tooling to reduce the force required to bend the material. Because of this, thicker material requires larger flange lengths so that the material to fit over the V-block. The width of the V block is usually seven times the thickness of the material.
When pressing tight radius, the grain direction needs to be considered. Bends should be placed across the grain to reduce the chances of cracking along the bend.
