A Novel Methodology to Manufacture Complex Metallic Sudden Overhangs in Weld-Deposition Based Additive Manufacturing

Abstract Amongst various additive manufacturing (AM) techniques for realizing the complex metallic objects, weld deposition (arc) based directed energy AM technique is attaining the more focus over commercially available powder bed fusion techniques. This is due to the capability of high deposition rates, high power and material utilization, simpler setup and less initial investment of arc based AM. Nevertheless, realization of sudden overhanging features through arc based weld deposition techniques is still a challenging task due to the necessity of support structures. The present work describes a novel methodology for producing complex metallic objects with sudden overhangs without using supports. This is possible by re-orienting the workpiece and/or deposition head at every instance using higher order kinematics (5-axis setup) to make sure the overhanging feature is in-line to the deposition direction. The proposed technique identifies the sudden overhangs form a CAD model (.stl) and generates an orthogonal tool path for deposition of the same. To validate this technique, objects with sudden overhangs (illustrative case studies) have been taken up for deposition. An In-house MATLAB routine has developed and presented for performing the same. Although this technique is suitable for any deposition process, it has been demonstrated using gas metal arc welding (GMAW) based weld-deposition, where the raw material to be deposited is in the form of a welding wire.