Hydroforming is a specialized type of cold forming that uses a high pressure hydraulic fluid to press room temperature tubes into a die.
The process consists of pre-bending a metallic tube and placing this pre-shaped tube inside a die with the desired cross sections and forms, and applying pressure to the inside of the tube held by the die. During the blowing or forming of the tube held in the die, holes can be pierced into the tube thereby avoiding secondary operations in most cases. Hydroforming allows complex shapes with concavities to be formed, which would be difficult or impossible with standard stamping.
Hydroforming is considered to be a cost-effective way of shaping metal into lightweight, structurally stiff, complex and strong pieces. One of the advantages of using this process is that it enables us to create a three dimensional tube that in cold stamping only could be manufactured by welding two shells together. The ability to deform thick materials makes this technology useful for chassis applications in particular.