Hybrid-layered manufacturing using tungsten inert gas cladding

Abstract

Among the different additive manufacturing (AM) processes, hybrid-layered manufacturing (HLM) is the AM process of metals which combines the best features of additive and subtractive manufacturing techniques. In HLM process, the metal is deposited by a cladding process and after the deposition of near-net shape, a machining operation is used for achieving dimensional accuracy. In this work, TIG cladding-based HLM process has been studied and stabilized by retrofitting a TIG cladding unit on an existing CNC machine. The behavior of TIG-HLM process has been studied for a mild steel cladding wire ER70S-6 of 1.2 mm diameter by performing the three types of experiments: single-bead, multi-bead and multi-layer experiments. The single-bead experiments are performed along with Taguchi and ANOVA to find out the contribution of process parameters such as cladding current, torch speed, wire feed rate and standoff distance on the bead width, height and penetration. The multi-bead experiments are performed to find out the optimal height of a layer where bead width is the input parameter. The multi-layer experiments are required for the characterization of the process and consist of hardness test by nano-indentation testing, microstructure analysis by electron backscattered diffraction, and interlayer fusion test by X-ray analysis. A case study has been done by manufacturing a cylindrical object of 50 mm height using this process.