Molten pool stability of thin-wall parts in robotic GMA-based additive manufacturing with various position depositions

Robotic gas metal arc (GMA) based additive manufacturing is regarded as a potential technology for the fabrication of large-size metal components with complex shape. However, as wire feed speed increases in GMA, molten pool of thin-wall parts becomes unstable due to powerful impact of arc force, leading to poor forming quality. In this study, a modified method changing the inclination angle theta between the GMA torch and substrate was proposed to improve the molten pool stability of thin-wall parts. The molten pool stability of thin-wall parts deposited with various positions in which the inclination angle ranged from 45 degrees to 135 degrees was investigated. Experiments indicated that the molten pool stability of thin-wall parts was improved effectively by decreasing the inclination angle. Compared with vertical (theta = 90 degrees) and backward (theta > 90 degrees) positions, depositing with forward position (theta < 90 degrees) is capable of improving the deposition rate without decreasing the forming quality.