Hydroforming Finding New Uses In The Automotive Industry.(Brief Article)

Hydroforming, a process that has been used in the metals industry for several decades, has caught the attention of the automotive industry and is quickly revolutionizing the way chassis and suspension parts are produced by OEMs and parts suppliers worldwide, according to George Morvey, Senior Consultant in Kline and Company's Petroleum & Energy Practice. He explains that this revolution is also spreading to the metalworking fluids industry sector, providing new opportunities and challenges for formulators and suppliers as well as end users of metalworking fluids.

Hydroforming is a process that provides an attractive alternative to conventional matched die stamping, especially for cost-sensitive parts with asymmetrical or irregular contours, Morvey said.

Since the Model T, the automotive industry has stamped metal shapes from sheet steel and then welded these shapes into engine cradles, suspension parts, and entire frames. The hydroforming process eliminates the need for costly stamping and welding operations by allowing parts producers to form the final shape of the part from a tube of steel using fluid under high pressure to force the steel to conform to the shape of the die.

There are many variations of hydroforming, but the process adopted by the automotive industry is tubular high- and low-pressure hydroforming. Tubular hydroforming involves taking a steel tube, bending it to conform to the near end shape, and forcing a pressure media (usually water with small volumes of oil, which includes a rust/corrosion inhibitor) through the tube at high or low pressures to force the tube to conform to the shape of the die. The outcome is a finished part that requires no welding but only surface treatments like laser cutting, trimming, and painting before it's ready for the assembly line.

Hydroformed parts can be made stronger than stamped and welded parts and are also lighter in weight, which contributes to improved fuel economy.

According to Morvey, "the lubricants used in hydroforming differ from conventional drawing and stamping fluids and look more like coolants." Lubricant requirements also differ between high- and low-pressure tubular hydroforming processes. For example, in high-pressure hydroforming, lubricants are required on the outside of the steel tube to protect the die surfaces. These lubricants are typically a dry film or solid-type barrier lubricant such as graphite or molybdenum, or calcium carbonate dispersions.

Additive requirements also differ between stamping fluids and hydroforming fluids, as hydroforming fluids require no chlorine or sulfur additives.

The automotive industry is making good use of this newly adopted technology as it converts its forming operations to produce radiator supports, engine cradles, instrument panel supports, frame rails, and other under-the- hood components and assemblies.

The redesigned 2002 Dodge Ram uses hydroformed frame parts to reduce chassis vibration. Suppliers of suspension parts to GM's new mid-sized SUVs use hydroforming to allow more vehicle models to share the same platform, resulting in an increase of up to 20 percent in manufacturing productivity for some parts, as well as weight savings of up to 30 pounds per vehicle, Morvey said.

The use of hydroforming is not limited to American car manufacturers. Opel, the German automaker, has constructed a plant in Germany that is producing hydroformed engine cradles, and Volkswagen expects to be producing 750,000 rear-axle support frames for its Beetle automobile using the hydroforming process, Morvey said.

In the past, using deep drawing methods, Volkswagen had to produce four separate components to make the frame. Using hydroforming, that number has been reduced to only one part required to manufacture the frame, Morvey added.

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