The 403 Series 4-roll double pinch plate bending machine is in a sense a 3-roll initial pinch plate bending machine with an extra bending roll on the front side of the pinch rolls. The advantage of this type of machine is that it enables the operator to roll the workpiece from the leading to the trailing edge with minimal and usually negligible flats. As a rule of thumb, the flats are less than 1 1/2 to 2 times the work piece thickness. This can be accomplished in a single pass without turning the workpiece.
