Incremental Inline Testing for Additive Manufacturing

Referencing of the powder bed for measuring the layer offset and the layer thickness

 

Dynamic optical and thermographic measurement of the melt pool

Professor Hausotte
Martin Heinl

The quality of SLM manufactured components is influenced by many different factors. Shrinkage, warpage and material inclusions, as well as variations in the surface roughness affect the functionality of the components.
In part project C4, an incremental inline testing based on the optical measurement principles was developed. For laser beam melting of polymers the measuring strategies, optical coordinate measuring systems and sensor cooling concepts are implemented and evaluated. However, it was also recognized that the causes of geometric component deviations, gotten with the incremental measurements, cannot be clearly assigned and therefore a targeted correction of production parameters can be carried out only with high uncertainties. Therefore, subject of further work, is to expand the existing photogrammetry based inline measurement technology on the one hand. On the other hand, the measurement of such variables as laser power, melt pool size, temperature of the setup and measurement system as well as referencing of the measurement system should be realized to shorten the metrological circle and to reduce uncertainties. The cause-effect relationships for manufacturing deviations can be better quantified, which contributes to an improved understanding of the process. This allows for a correction of the influences as well as the improvement of the reproducibility and accuracy of SLM produced components. A combination of obtained knowledge and information obtained during the monitoring of the component brings the opportunity to evaluate the form deviation of the ideal geometry and to provide its correction.

Aim of the research:

  • Inline monitoring of the relevant process parameters and determination of the cause-effect relations for ensuring the compliance of the workpiece's shape with the geometric tolerances.
  • Defined influences.
  • Increasing of the measurement accuracy for the Inline measurement system by referencing of the powder bed, as well as shortening of the metrological chain.
  • Higher accuracy of the workpiece shape measurement.
  • Development of strategies for correction and compensation of shape variations based on the detected cause-effect relations.
  • Defined temperature distribution.

Prof. Dr.-Ing. habil. Tino Hausotte
Lehrstuhl für Fertigungsmesstechnik (FMT)
Friedrich-Alexander-Universität Erlangen-Nürnberg
Nägelsbachstraße 25
91052 Erlangen
tino.hausotte@fau.de

Martin Heinl, M.Sc.
Lehrstuhl für Fertigungsmesstechnik (FMT)
Friedrich-Alexander-Universität Erlangen-Nürnberg
Nägelsbachstraße 25
91052 Erlangen
martin.heinl@fmt.fau.de