Abstract: A flow-turning process for manufacturing internally geared parts, including a press mandrel (10) comprising a mandrel (1) on which is fitted a forming tool (2) and one or more pressure rollers (3). A workpiece (4) is held between the forming tool (2) or press mandrel (10) and press rollers (3) and undergoes plastic deformation under the force exerted by the press rollers (3). The forming tool comprises chromium- and molybdenum-containing materials and is tempered and surface-hardened, and the distance between the forming tool (2) and the mounting of the press mandrel (10) in the machine is sufficient to permit a degree of deviation (.alpha.) by the forming tool (2) relative to the machine axis (5).