Hydroforming

Hydroforming is a metal forming process that uses high-pressure hydraulic fluid to shape ductile metal into desired forms. Instead of mechanical drawing or stamping alone, pressure is applied by a fluid to push the metal into a shaped die, enabling complex geometries and smooth interior surfaces with fewer welds.

There are two principal variants: tube hydroforming and sheet hydroforming. In tube hydroforming, a hollow tube is clamped within a forming die and internal fluid pressure expands the tube to fill the die cavity, producing shapes that may integrate features such as flanges and undercuts. In sheet hydroforming, a blank is placed on a die and hydraulic pressure pushes the sheet into the hollow cavity, forming complex panels with smooth radii and contours.

Process considerations include dies able to withstand high pressures and the use of clean, compatible forming fluids. Typical steps involve fixturing, sealing the forming zone, fluid pressurization, forming, trimming, and finishing. The method can reduce tooling costs and assembly steps by eliminating welds, particularly in tubular components for automotive and aerospace applications.

Materials and applications: aluminum, stainless steel, copper, and titanium are commonly formed by hydroforming. Tube hydroforming is widely used to produce lightweight automotive frames, exhausts, and aerospace components, while sheet hydroforming serves complex body panels, brackets, and housings.

Advantages and challenges: hydroforming offers near-net shapes, good surface finish, and reduced weight; however, it requires specialized equipment, careful process control, and dies designed to withstand high pressures. Potential defects include thinning, wrinkling, and misalignment if forming limits are exceeded.