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Hydroforming is a plastic processing technique that uses a liquid as a force-transmitting medium or die to shape workpieces; it is also known as hydraulic forming. Depending on the liquid medium used, hydroforming is divided into water hydroforming and oil hydroforming. The medium used in hydroforming is pure water or an emulsion composed of water to which a certain proportion of emulsified oil has been added; the medium used in hydropressing is hydraulic transmission oil or engine oil. Depending on the type of blank used, hydroforming is divided into three types: Tube Hydroforming, Sheet Hydroforming, and Shell Hydroforming. The forming pressure used for hydroforming sheet metal and housings is relatively low. Hydraulic forming of pipes requires high pressures; it is also known as Internal High Pressure Forming. The medium used in sheet metal hydroforming is usually hydraulic oil, and the maximum forming pressure generally does not exceed 100 MPa. The medium used for hydroforming the housing is pure water, and the maximum forming pressure generally does not exceed 50 MPa. The medium used in internal high-pressure forming is mostly an emulsion, and the maximum forming pressure employed in industrial production generally does not exceed 400 MPa. The main characteristics of modern hydroforming technology, which was developed in the mid-1980s, are evident in two aspects. Firstly, only a female die or a male die is required; the liquid medium serves as either the male die or the female die, which allows for a reduction of half the costs associated with molds as well as the processing time. Moreover, since the liquid can function as a male die, it is possible to shape complex parts that cannot be formed using rigid male dies. In the case of hydroforming of shells, no molds are used at all; hence this process is also known as moldless hydroforming. Secondly, as a force-transmitting medium, liquid offers real-time controllability; through hydraulic closed-loop servo systems and computer control systems, the pressure can be precisely controlled according to predetermined curves, ensuring that the process parameters remain within set values. Moreover, these parameters can be changed and adjusted over time, **increasing the flexibility of the process. In addition to these characteristics, the three different hydroforming techniques—internal high-pressure forming, sheet hydroforming, and shell hydroforming—each have their own distinct features.