Adaptive control of filler wire speed in Wire Arc Additive Manufacturing (WAAM)

Abstract

Wire arc additive manufacturing (WAAM) is known for filler wire melting under the influence of electric arc and controlled metal deposition in a layering fashion using a computer numerical controlled (CNC) worktable or robotic head. Gas metal arc welding (GMAW) enabled WAAM system excels more in the AM field due to coaxial wire feeding mechanism, high process efficiency, low investment cost, and improved product strength. But it endues with nonuniform layer height, spatter, thermal distortions, metal overflow, and mechanical anisotropy. The prime cause for these issues is improper thermal energy management due to the current controlled wire feed speed (WFS). Here, an autonomous wire feed system (AWFS) has been designed, which fine-tunes the WFS of 316L stainless steel (SS) feedstock irrespective of the welding current values. So adequate control over arc current generation is achieved, supporting thermal energy management during the entire deposition process. AWFS integration with GMAW-WAAM endues a thin-layered structure with negligible metal overflow, low spatter, and uniform layer height. In addition to the macrostructural improvements, an enhancement in the δ-ferrite concentration has been noticed in the micrographs and X-ray diffraction graphs that substantially diminishes the corrosion rate to 0.0287 mm/year. Apart from this, the anisotropy in the mechanical strength is successfully kept below 5%. These improvements in the microstructural, chemical, and mechanical properties of the fabricated 316L SS component further directed the application of WAAM towards the biomedical fields such as implant manufacturing.