Influence of optical system operation on stability of single tracks in selective laser melting

Abstract

Additive manufacturing (AM) technologies are increasingly being studied and introduced into the modern industry, but for wide applications there exists some "lack of confidence" about the quality of the parts produced by AM. This distrust has an objective basis: it was shown that final 3D object is a superposition of a huge number of tracks and layers, and deviations from the optimal process parameters can lead to non-regular shape, un-melted places (lack of fusion) and porosity that is one of the most undesirable effects in laser powder bed fusion (LPBF). Experiments with different bare substrates and powders were done to classify instabilities and artifacts in single tracks derived from laser beam characteristics, the optical system, scanning strategy, etc. demonstrating an elaborated adjustment scheme for testing and verification SLM equipment. The proposed scheme was used to evaluate in situ diagnostics of the SLM processes on an experimental setup such as the Additive Manufacturing Metrology Testbed (AMMT) at National Institute of Standards and Technology (NIST).