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Also known as unconventional deep drawing and Flexforming, hydroforming is a method of shaping metal using a synthetic rubber diaphragm, a punch and pressurized hydraulic oil. In a hydroforming operation, the work-piece to be formed—the blank—is placed on the draw ring. The rubber diaphragm is then lowered onto the blank. There is a cavity for hydraulic fluid behind the diaphragm. As the diaphragm fits over the blank, pressurized hydraulic oil is sent into the cavity so that it forces the blank to mold around the shape of the punch. The punch is then pushed into the pressurized diaphragm and hydraulic fluid. As the punch drives into the diaphragm, the blank forms around it, creating the finished shape. The hydroforming system then removes the finished work-piece and inserts a new blank so that the process can be repeated.



Hydroforming is identical to stamping in many ways, except that the pressurized rubber diaphragm serves as the other half of the die set to the punch. The pressure of the hydraulic fluid typically ranges from more than 10,000 to 30,000 pounds per square-inch (psi). Hydroforming is also an extremely cost-effective alternative to stamping for many components. In fact, more complex parts may entail greater savings. This is because hydroforming can streamline a multi-stage manufacturing operation into a single process. However, there are limitations to the part shapes and complexity that can be produced with this operation.



It is suitable for nearly all sheet metals, and often provides more part consistency due to the uniformity of the fluid pressure. The maximum thickness that can be hydroformed varies between materials. Aluminum and brass, for instance, can be hydroformed in thicker shapes than stainless steel. Production cycles for a part range between one and three minutes, but it has drastically reduced tooling costs. Its time limitations coupled with its affordability make it an ideal choice for smaller production runs, although it can be used for any suitable operation.