Hydroforming

This technique is particularly popular with the high-end sports car industry and is also frequently employed in the shaping of aluminium tubes for bicycle frames.

Hydroforming allows complex shapes with concavities to be formed, which would be difficult or impossible with standard solid die stamping.

Virtually all metals capable of cold forming can be hydroformed, including aluminium, brass, carbon and stainless steel, copper, and high strength alloys.

[clarify][1] Electrohydraulic forming uses electrodes to vaporize the fluid explosively in an arc to deform the working material.

This process is based on the 1950s patent for hydramolding by Fred Leuthesser, Jr. and John Fox of the Schaible Company of Cincinnati, Ohio in the United States.

Among these techniques hydraulic bulge testing allows for an increased work hardening of sheet material by distinctive stretching operations and provides better shape accuracy for complex parts.

Designing the process has in the past been a challenging task, since initial analytical modeling is possible only for limited cases.

[10] Advances in FEA and FEM in recent years has enabled hydroform processes to be more widely engineered for varieties of parts and materials.

Often FEM simulations must be performed in order to find a feasible process solution and to define the correct loading curves: pressure vs. time and axial feed vs.

However, the process is limited by the very high closing force required in order to seal the dies, especially for large panels and thick hard materials.

in fact, the die closing force can be very high, both in tube and sheet hydroforming and may easily overcome the maximum tonnage of the forming press.

Metal hydroforming also allows for a smoother finish as draw marks produced by the traditional method of pressing a male and female die together are eliminated.

This may in part be a result of the relatively low levels of springback naturally occurring when deforming the tubes into their closed section geometries.

For this reason it is likely that negative residual stress induced during tube hydroforming might be insufficient to deform the part elastically after the completion of forming.