Anforderungen und Randbedingungen für den Einsatz optischer Messsysteme zur In-Line-Prüfung additiv gefertigter Bauteile

Abstract

Additive manufacturing processes such as selective laser melting (SLM) are increasingly evolving due reduction of the manufacturing and reworking time from pure prototyping (rapid prototyping) into quantity flexible production of individual parts (rapid manufacturing). Despite the great potential of the tool-free generation of complex and individual components with almost unlimited freedom in design, reluctance still exists for the use of this manufacturing process because of inacceptable quality defects in shape and strength, which are mainly caused by process variations (temperature, energy density of the laser, powder quality, etc.) during the layered-base manufacturing. To detect such errors not only after the production – as in today's approach by complex uneconomic reference samples and specimens – a quality inspection embedded in the manufacturing process and a derived process control is becoming increasingly important. A possible solution presented in this paper is an incremental in-line measurement procedure, which is performed before, during and after each layer assembly. To determine an qualified measuring system, which will in future enable a dynamic and fully automated process control, the SLM-process is analyzed in consideration of its metrological requirements (vertical and lateral sensor resolution, reflection properties, etc.) and restrictions on the manufacturing machine (available space, temperature, powder material, etc.). In addition, appropriate sensors, which are feasible in an in-line-measuring-system for an SLM process for polymers, are tested and evaluated for their capability. Finally, a possible implementation concept is proposed based on fringe projection.