Deposition Geometrical Characteristics of Wire Arc Additive Manufactured AA2219 Aluminium Alloy With Cold Metal Transfer Pulse Advance Arc Mode

A cold metal transfer pulse advance (CMT-PA) arc mode was employed in this paper for the additive manufacturing of Al alloy. The effects of process parameters on the surface morphology and effective width percentage were investigated. And a deposition width model was built by the multiple linear regressions. Based on the principle that the volume of sample is equal to that of filler wire, a deposition height model was simultaneously derived. The results show that the process parameters affect the trends of droplet spreading in horizontal direction and molten pool tangential direction by changing the heat input and arc force. The disparity between two trends directly determines the final deposition geometrical characteristics. The influences of three factors on the effective width percentage show a trend of first increasing and then decreasing. So it provides a process window of good deposition forming. Using the optimal parameter in the window, the effective width percentage reaches to 83% and machining allowance is only 0.8 mm, which significantly improves materials utilization and reduces manufacturing costs. Besides, the error rates of deposition width and height models are less than 4% and 6%, respectively. Two models can facilitate manufacturing different size parts and make a profit for the actual production.

Analysis of Metal Transfer and Weld Forming Characteristics in Triple-wire Gas Indirect Arc Welding

Triple-wire gas indirect arc welding (TW-GIA) has the advantages of low heat input and high deposition rate. However, the simultaneous melting of triple wires makes the metal transfer mode complicated. The unknown of the metal transfer mode restricts the development of this technology. In this paper, high-speed camera systems and electrical signal acquisition sensors were used to explore the TW-GIA metal transfer mode. The static force model and the arc conductive channel model were used to discuss the droplet force and energy conversion characteristics respectively. Results showed that the TW-GIA metal transfer modes can be divided into: short-circuit transfer (SCT), main wire projected transfer + side wire globular transfer (PGT), main wire streaming transfer + side wire projected transfer (SPT) and main wire streaming transfer + side wire streaming transfer (SST). Moreover, the process parameter ranges corresponding to the four modes were summarized. Due to the stable arc and the uniform metal transfer process, SPT and SST can form desirable weld seam. The gravity and z-axis components of electromagnetic force are the main forces that promote metal transfer. The x-axis and y-axis components of the electromagnetic force deviate the metal transfer path from the arc coverage. Due to the change of arc conductive channel, the energy transferred from TW-GIA to the base metal is less than that of GMAW, showing the advantages of small welding deformation, narrow heat affected zone and grain refinement.