Spatio-temporal temperature models for growing 2D workpieces during DLD with emissivity compensation for thermal imaging

One of the concerns in the additive manufacturing of metallic pieces is the lack of quality assurance and consistency. To address this, it is necessary to have closed-loop control of the temperature and cooling rate not only at a single point but throughout the whole workpiece. This paper presents a method to create control-oriented spatio-temporal temperature models for 2D workpieces in Direct Laser Deposition and identify them with thermal imaging data. Data from laboratory experiments during the production of workpieces of two different geometries were used to validate the method. An emissivity compensation method was devised to correct the temperature estimation from the infrared measurement around the melt pool area. The performance of the models obtained was assessed so as to suggest further improvements.