Hydroforming is a cold forming process by high pressure hydraulic fluid (water or oil and water emulsions), to press stainless steel tubes or sheets into a die at room temperature.

Hydroforming can be made from a stainless Steel tube, profile or sheet that submitted to internal pressure become a hollow piece.

Sheet hydroforming

Stainless steel sheet hydroforming is based on the application of pressurized fluid to make the sheet adopting the shape of the die.  The pressure increase is obtained through hydraulic systems.  Sheet hydroforming can be made using different methods depending on the sheet (simple or double).

When hydroforming simple sheet with mould, this is used as a negative of the final shape in one of the sides and through a hydraulic mechanism which supplies pressurized fluid to push the sheet against the mould.  The material expands and deforms by pressure inside the mould.

When a punch is used, the sheet is placed on the mould, the perimeter is sealed and through a hydraulic press the pressurized liquid is put into it forming the material.

When a punch is used, the sheet is placed on the mould, the perimeter is sealed and through a hydraulic press the pressurized liquid is put into it forming the material.

The process defined by forming simultaneously two pieces is double sheet hydroforming.  Once they are welded together a high pressurized fluid is inserted between the two pieces making them adopt the shape of the mould.  By this method hollow and structural shapes and tank pieces are made as the one of the picture.

Tube hydroforming

Tube hydroforming is made by injecting pressurized fluid to form a stainless steel tube against the mould. The fluid is injected into the tube through one of the two axial punches. Axial simultaneous compression is used to avoid the excessive thinning of the tube thickness in areas submitted to too high expansion. In the automotive industry, hydroforming is mainly used in the manufacturing of exhaust systems, chassis and body vehicles.