Calibration approach for reliable in-situ process monitoring of multi-optic selective laser melting

Abstract Additive Manufacturing is on the threshold of full industrial use in various leading industries. This is due to the continuous development of machine systems regarding availability, stability, reproducibility and repeatability alongside their ever-increasing productivity. To achieve high quality parts, process variables must be monitored during production, for example with a Melt Pool Monitoring (MPM) system to measure their characteristics. Initial and long-term stable calibration of the monitoring system must be ensured with proper alignment, positioning and the size of the measuring surface itself. To secure direct comparison of multi-optics within a machine as well as transferability from machine to machine, a quantitative intensity calibration must also be carried out. This paper provides a new calibration approach with measuring equipment and tools including a Measurement System Analysis (MSA), exploring possibilities and limitations in terms of absolute accuracy, repeatability and reproducibility as well as workflows for the measurement equipment and machine calibration.