The process setup (build orientation optimization and support structure design) for a pre-existing part is of large practical importance, e.g., in the service and reconditioning market. It is demonstrated here for a pump impeller.
There is a strong market demand for small high-pressure pump systems in the water industry. However, the casting of impellers for such small pumps in the essential quality is difficult or impossible due to their low wall thickness and their unfavorable ratio of impeller diameter to duct height.
Production of impellers by laser melting
Selective Laser Melting (SLM), one of the most critical technologies for the additive manufacturing of metal parts, is well suited to be used for such impellers, as the full potential of SLM can best be achieved with such small, intricate pieces. We have carried out the SLM manufacturing of an existing impeller design at the lower limit of castability. This has the advantage that the SLM component can be tested on a current pump prototype and directly compared to the cast counterpart. A scale-down to smaller sizes (up to a certain limit), which can no longer be produced through casting, is then not hindered by any significant obstacle.
Development of the process structure
Our main task was to find the optimal orientation of the building direction and to design a suitable supporting structure. This took place in a heuristic and iterative process with simultaneous production trials. The final SLM-manufactured prototype impeller met all geometric requirements and will be tested soon in the existing prototype pump.
While major part redesigns exploit the full potential of SLM production, the production of existing part geometries is in demand for applications in the service and repair market in water management and beyond. To produce these successfully, the optimization of the process structure (build orientation optimization and planning of the support structure) for an already existing part geometry is of great practical importance.
