Abstract
In this paper, we present the results of a study on droplet transferring with arc space short circuits during wire-arc additive manufacturing (WAAM GMAW). Experiments were conducted on cladding of single beads with variable welding current and voltage parameters. The obtained oscillograms and video recordings were analyzed in order to compare the time parameters of short circuit and arc burning, the average process peak current, as well as the droplets size. Following the experiments conducted, 2.5D objects were built-up to determine the influence of electrode stickout and welding torch travel speed to identify the droplet transferring and formation features. Moreover, the current–voltage characteristics of the arc were investigated with varying WAAM parameters. Process parameters have been determined that make it possible to increase the stability of the formation of the built-up walls, without the use of specialized equipment for forced droplet transfer. In the course of the research, the following conclusions were established: the most stable drop transfer occurs at an arc length of 1.1–1.2 mm, reverse polarity provides the best drop formation result, the stickout of the electrode wire affects the drop transfer process and the quality of the deposited layers. The dependence of the formation of beads on the number of short circuits per unit length is noted.
Highlights
Wire-arc additive manufacturing is one of the promising methods for obtaining high-precision work-pieces (WAAM) [1]
There are several varieties of wire-arc additive manufacturing (WAAM) cultivation, the main ones are based on the technologies of gas arc welding with a tungsten electrode (GTAW) [2] and gas melting arc welding (GMAW) [3]
The latter method is most convenient for use in WAAM, since there is no additional problem of positioning the wire feed
Summary
Wire-arc additive manufacturing is one of the promising methods for obtaining high-precision work-pieces (WAAM) [1]. There are several varieties of WAAM cultivation, the main ones are based on the technologies of gas arc welding with a tungsten electrode (GTAW) [2] and gas melting arc welding (GMAW) [3] The latter method is most convenient for use in WAAM, since there is no additional problem of positioning the wire feed. The most favorable transfer occurs when the droplet passes through the arc space short circuit In this case, the welding current is lower than in other transfer modes, and the arc burning is not constant, which reduces the heat input [10]. Most researchers use the cold metal transfer (CMT) method [11,12,13,14,15,16,17] It allows to separate the molten droplet by mechanical action on the wire, reducing the process temperature.
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