The article is dedicated to conditions under which the cutting of a thin-walled cylindrical workpiece is carried on the cutting knife-edge with combined electrohydroimpulse forming of the hollow parts with the flat flange. Empirical relationship of the ultimate workpiece deflection during its ring gap molding at the moment of separating the material from the material parameters, geometrical sizes and equipment of the workpiece is gained. Computer simulation of the studied process in the finite-element complex LS-DYNA is modeled. Studies have shown that the electrohydroimpulse forming at a time can combine operations such as distribution, molding, cropping, piercing, sizing and flanging. This technology can be effectively used in the making of the hollow spatial parts with the flange.