What is Hydroforming?

Hydroforming is a cost-effective and specialised type of die moulding metal fabrication and forming process which utilises highly pressurised hydraulic fluid to shape metals such as steel, stainless steel, carbon, copper, aluminium and brass into lightweight, strong and structurally stiff pieces. Virtually all metals capable of cold forming can be hydroformed.

Hydroforming allows complex shapes with concavities to be formed which would be very difficult to achieve with standard solid die stamping.

One of the largest applications of hydroforming is in the automotive industry which requires complex shapes that are lighter, stronger and more rigid. The process is also frequently employed in the shaping of aluminium tubes for bicycle frames.

Other benefits of parts created by the hydroforming method include seamless bonding and increased part strength. They also maintain high-quality and less grainy surfaces for easier metal finishing purposes.
Generally, there are two classifications to describe hydroforming:

Sheet Hydroforming (SHF)

Bladder forming, aka flex forming, is where a bladder contains the forming liquid so that no liquid touches the blank metal sheet. This is mostly used for low volume productions such as in the aerospace field.

Forming with direct contact, aka hydro-mechanical deep drawing, is when the forming fluid comes into direct contact with the metal sheet using a male solid punch.

A workpiece is placed on a draw ring or blank holder, over a male punch. A hydraulic chamber surrounds the workpiece and low-pressure seats the workpiece against the punch. The punch is then raised into the hydraulic chamber and the pressure increased up to 100MPa which forms the part around the punch. To complete the process the pressure is released, the punch retracted and the hydraulic chamber lifted.

Tube hydroforming

Tube hydroforming is the expansion of metal tubes into a shape using two die halves, which contain the raw tube. Hydroforming replaces the older process of stamping two halves and then welding them together. The hydroforming not only makes the parts more efficiently but is also able to create complex shapes and contours.

Advantages of Hydroforming

Hydroformed parts are not only lower in cost per unit but the processes can be utilized in a single stage production of components which saves on tools, materials and labour.

Tools and punches can be interchanged. For sheet metal, only a draw ring and punch or male die are required. Depending on the part being formed, the punch can be made from epoxy. With bladder forming, the bladder acts as the female die which eliminates the need to fabricate it. In tube hydroforming, a two-piece die is required to allow opening and closing.

Steelmor is the leading supplier and manufacturer of stainless steel in South Africa and is dedicated to supplying cost effective quality products on time. Give us a call to find out how we can best assist you with your stainless steel requirements.

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