Recently, the adjustment of working conditions in a manufacturing process is indispensable for realizing manufacturing accuracy in the V bending of a sheet metal. This adjustment is called "Trial Processing", and is a factor for lowing productivity. Therefore, "Trial Processing Free", a method that can obtain accuracy within tolerance but without the adjustment, is required. In the V bending of a sheet metal, there are two types of bending process, i.e., (i) air bending and (ii) bottom bending, using two types of punch control, i.e., (a) stroke control and (b) force control. In this research, a series of analysis and experiments were carried out to clarify that (ii) bottom bending with (b) force control is most appropriate for achieving Trial Processing Free. It was also established that bottom bending at an appropriately controlled force can absorb the effect of uncontrollable factors such as the dispersion of thickness and material properties of sheet metals and bend sheets within a certain tolerance, because the bending angle is stable even in a very wide range of bending forces. This bending method with force control was called the "FCSS (Force Control to Sweet Spot) method" and the advantage of this new process was verified experimentally.
