Flow Forming

Flow forming is an innovative production process enabling companies to show responsibility, economically as well as ecologically. There are two aspects to the process' profitability: on the one hand companies spend less on energy and material, on the other hand the material's characteristics are upgraded. At the same time, this economical production process is environmentally friendly as far less resources are used than in alternative procedures. Flow forming allows using lower grade and therefore mostly cheaper material which is used optimally in the production process. Additionally, drastically reduced post-processing saves even more on time and energy. The process results in improved dynamic material characteristics providing increased workload and longer lifetime. Also, reduced weight and the lower moment of inertia cut energy costs.

In flow forming, the two process variants forward and reverse flow forming are distinguished. They are discriminated by the particular direction of plastic material flow. In forward flow forming, material flow is in parallel to the axial roller feed. The part of the blank not yet subject to material flow is pushed forward by the rollers’ action. Blanks used are cups whose bottoms or internal flanges are pressed onto the free end of the mandrel via the forces exerted by the tailstock and a pressing plate.

If a blank does not have a bottom or internal flange, reverse flow forming provides a way out. Here, the blank is slid onto the forming mandrel until it reaches its clamping position. At this point, a traction ring equipped with hardened teeth gets hold of the blank. The blank is then pressed against the toothed segment due to the axial forces of the rollers, thus inducing a rotational motion. Plastic material flow during forming takes place underneath the rollers, initially towards the free end of the forming mandrel and subsequently into the free working space of the machine. Thus, the direction of material flow is opposite to the longitudinal feed. In contrast to forward flow forming, possible workpiece lengths are not restricted by the longitudinal feed of the support and the mandrel length. Therefore, while reducing wall thickness by e.g. 60 %, the workpiece length can reach 2.5 times the length of the maximum stroke of the support.