It is also possible to produce pressure in the fluid at the beginning of the process by a pump system. This makes it possible to have a prebulging of the blank. The initial pressure has the advantage of preforming the work piece along with inducing a work hardening in the middle of the part. This work hardening can be useful in flat parts to produce stiffer and more geometrically accurate products with more hardness, which is useful for a better hail impact (dynamic denting). It can also be useful to have a prebulging in order to get more sheet metal into the die cavity when drawing deep parts. Further, it is possible to have a hydraulic forming of parts into the cavity of the die when using no punch but only a rigid die cavity.