Manufacture of complex thin-walled metallic objects using weld-deposition based additive manufacturing

Gas Metal Arc Welding (GMAW) based weld-deposition process is one of the deposition-based Additive Manufacturing (AM) processes with the ability to produce fully dense complex functional metallic objects. Due to its high deposition rates, high material and power efficiency, lower investment costs, simpler setup and work environment requirements it is slowly becoming a viable metallic AM method. Amongst various geometrical features that can be realized in weld-deposition based AM, the thin-walled features (i.e., features with one single deposition pass) are the toughest as the process has to overcome the bead-over-bead complexity. Based on geometric modelling and experimentation, this paper presents an efficient technique for producing the thin-walled metallic structures, including objects with undercut features. This is possible by adding extra degrees of freedom or by using higher order kinematics to the work piece and/or to the deposition head by suitably aligning the overhanging feature in-line to the deposition direction. An in-house MATLAB code was developed to slice the CAD model and generate the tool path for inclined deposition of a given layer of a thin-walled model. A geometrical model proposed to predict the layer thickness of a given layer during such bead-on-bead deposition showed good correlation with experimental data. Some illustrative complex thin-walled components successfully fabricated using this model have also been presented.