Investigation on Surface Quality in a Hybrid Manufacturing System Combining Wire and Arc Additive Manufacturing and Machining

Wire and arc additive manufacturing (WAAM) has gained popularity in recent years due to its unique efficiency and cost advantages. Nevertheless, due to the stair-stepping effect and the liquidity of molten metal, the achieved geometric accuracy and surface quality are still very limited. The combination of WAAM and machining, namely hybrid manufacturing, provides a fundamental solution to the above problem. Because machining is performed after depositing several layers, the deposition width, deposition height, and surface waviness have great effects on the machined surface quality, in addition to the machining parameters including spindle speed and feedrate. In this paper, the dependence of the machined surface quality (characterized by surface roughness) on the influencing factors mentioned above is investigated based on quadratic general rotary unitized design (QGRUD). To reduce the number of experiments, a comprehensive factor, namely material removal area (MRA), is introduced to characterize the deposition width, deposition height, and surface waviness. The analysis results show that spindle speed is the most influential factor, followed by MRA and feedrate. Furthermore, a high spindle speed and a moderate feedrate are preferred, which contribute to not only improving the surface quality and the efficiency but also reducing the demand of geometric accuracy for WAAM.