History, classification, and advantages of hydroforming

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The history of using fluids to form metals dates back over 100 years; it was initially applied in the manufacturing of boilers and musical instruments, and mainly falls into two categories: sheet metal hydroforming and tube hydroforming. This article, brought to you by Xingdiyuan Machinery, covers the history, classification, and advantages of hydroforming. 　　I. History of hydroforming: The history of using fluids to shape metals dates back over 100 years, with early applications in the shaping of boilers and musical instruments. However, the basic principles of hydroforming were established in the 1940s (Grey, 1939 ； Dohmann, 1991 and Koc, 2001). 　　In the 1950s, alternative manufacturing processes such as superplastic forming, explosive forming, and rubber forming were proposed to improve the formability of aluminum and other lightweight materials. In the 1950s, Milton Garvin of Schaible Company in Cincinnati, Ohio, filed the first patent application for hydroforming related to the production of kitchen nozzles. 　　Until the 1990s, manufacturing copper tubes was the most common application. 　　Since the 1990s, hydroforming technology has seen significant progress thanks to advantages such as computer control, hydraulic systems, and newly developed process and part design guidelines; various forged or stamped structural components have been replaced by parts formed using the Thermo-Hydraulic Forming technique (THF) for many North American vehicles. 　　Due to part consolidation, fewer post-forming processes (i.e., joining methods such as welding and piercing), and the possibility of using initially thinner material thicknesses, hydroformed steel parts achieve significant weight and cost savings (Dohmann, 1991) ； Koc，2001 ； Murray, 1996 and Morphy, 1997). 　　II. Classification of hydroforming: Generally, the hydroforming process can be divided into two main categories: (a) sheet hydroforming and (b) tube hydroforming, as shown in Figure 1.5. 　　III. Advantages of hydroforming: The advantage of hydroforming technology is that it reduces weight and costs by combining parts and eliminating subsequent forming processes such as welding and drilling. However, hydroforming technology has some shortcomings in terms of the number of process cycles required. However, with the continuous advancement of hydraulic systems and press design, the cycle time has also been reduced to an acceptable and competitive level. 　　Another important prerequisite of the internal high-pressure forming process is its capability to be used in manufacturing lightweight structures and components from lightweight materials. 　　During its service life, energy consumption accounts for about 80% of the total energy used over the car’s entire lifecycle; therefore, the use of lightweight structures is considered a significant and long-term solution that can minimize energy consumption and the negative environmental impacts of transportation, thereby enabling truly sustainable mobility (Merdenberger and Khare, 2000). 　　Even in vehicles equipped with efficient clean power generation systems and alternative fuels, lightweight structures will further improve fuel efficiency and reduce emissions (i.e., primary and secondary benefits). 　　Lightweight structures can be achieved by: (a) using lightweight materials such as aluminum, magnesium, high-strength steel, titanium-metal matrix composites (MMC), and polymer composites ； 　　(b) Developing low-cost, reliable conversion processes to enable the effective utilization of these materials (i.e., innovative manufacturing processes). 　　It is reported that for every 10% reduction in vehicle weight, fuel efficiency can decrease by about 6-8%. 　　In addition to its ability to manufacture complex parts cost-effectively, hydroforming can also shape lightweight materials into the desired form, with fewer problems compared to stamping. Aluminum, magnesium, and high-strength steel are the most suitable materials for lightweight structures ； However, their formability is very low, and they are highly sensitive to production speed. 　　In this regard, hydroforming offers an opportunity for manufacturers to shape these materials by precisely increasing the degree of deformation within the die through the application of fluid pressure. When combined with a selective heating strategy, hydroforming (warm forming) goes even further, increasing the forming limit by 100-300%.