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In recent years, hydroforming has clearly expanded its range of industrial applications due to the growing interest in products which combine high strength with low weight. A current limitation of this technology was its economically justified production volume since the costs of producing tools eliminates the possibility of using hydroforming technology in prototype and single part production. The paper presents a freshly patented solution that allows for single part hydroforming. The new technology combines traditional hydroforming machines with a new approach to tool production. The new rapid die is made quickly and cheaply. The use of materials known from the production of foundry moulds causes the die to deform during hydroforming, but it is a controlled deformation. Thanks to the use of numerical modelling, the deformation of the mould cavity is predicted and taken into account at the design stage. The article presents important issues that need to be considered in the design of this innovative process.

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In the recent years, the demand for weight reduction in modern vehicle construction has led to an increase in the application of hydroforming processes for production of automotive and aerospace lightweight components. The tube hydroforming measurement site (TH stand), designed and built at Warsaw University of Technology allows both die, and free tube hydroforming processes to be performed, thereby making it possible to obtain information about the material, as well as optimal process parameters [1][2]. The present freshly patented method for metal tube hydroforming is dedicated to short product series or even single products and prototypes [3]. The method is applicable to forming difficult-to-machine materials. The well-known techniques use dies made of plastic or wood, especially to form short product series. The use of moulding sand and properly prepared geometry of casting mould makes possible shaping materials at high temperatures, which could not be done in previous short series solutions, where a plastic or wooden die were used.

The article presents a newly patented rapid tube hydroforming (RTH) manufacturing method, perfectly suited to single-piece production. The RTH technology significantly complements the scope of hydroforming processes. Due to the unusual granular material of the die tool, in particular moulding sand or mass, the process design requires the use of numerical modelling calculations. This is related to the complexity and the synergistic effect of process parameters on the final shape of the product. The work presents the results of numerical modelling studies of the process, including the behaviour of the die material and the material of the hydroformed profile. The numerical calculations were performed for a wide range of parameters, and can be used in various applications. The significant properties of moulding material used for the RTH tests were determined and one was chosen to build the die in RTH experiments. The results of the numerical modelling were compared with the results of the experiments, which proved their high compatibility. The final conclusions of the analyses indicate that the RTH technology has many possibilities that are worth further development and research.

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The paper presents a discussion on the occurrence of defects in the circumferential flange of steel plate. The numerous flange face defects have been analysed. The types of defects have been selected and categorized using an experimental planning procedure involving 600 samples for 24 different process variants, considering variables such as material, hole diameter, tool size and tool position. The analysis of experimental results enabled to determine of the optimal values of process parameters to minimize the occurrence of defects. Furthermore, the influence of individual parameters on the quality of the flange surface has been carried out to obtain the process parameters' impact using statistical hypotheses. As a result, it was possible to develop rules which will be helpful in the design process, especially important when changing the material to be processed.

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