Direct laser deposition – A comparative study using different cw YAG lasers and with in situ real-time spectroscopy and imaging

摘要

Direct Laser Deposition (DLD) is an emerging technology which shows great potential for direct manufacture. The DLD method has become viable for the build up of three-dimensional parts, their repair or modification, as a means of rapid prototyping and tooling of metallic components. However, compositional monitoring of the DLD process still requires investigation. The in situ application of spectroscopy is a very powerful tool to get more information about the composition created during the DLD. Identification of elements by spectra lines can determine how the melt pool composition has been changed by laser irradiation in real-time. These investigations will allow the development of a non-contact composition monitoring technique for the DLD process. The work reported here centres on initial studies performed with different solid state, CW laser systems (conventional Nd:YAG fiber delivered to 6 axis robot and new high-powered Yb-YAG disc laser fiber delivered to an x-y stage) to investigate the feasibility of applying real-time spectroscopy and fast digital imaging to the DLD process. Several metal compositions have already been studied and two different wavelength spectrometers (UV-VIS and VIS-IR) have been used during the process to record spectra lines in situ.