Energy characteristics of droplet transfer in wire-arc additive manufacturing based on the analysis of arc signals

Abstract

The non-pulsed arc and pulsed arc were used in wire-arc additive manufacturing (WAAM) of aluminum alloys. Arc signals about arc current and voltage synchronized with the acoustic emission (AE) detected in manufacturing were used as information source to identify the droplet transfer mode. The calculations of probability density distribution, power spectrum distribution and energy gradient to synchronous time-domain signals were used to investigate the characteristics of metal droplet transfer and energy transfer. As a result, it was found that the characteristics of arc power signals and AE signals in WAAM process have a close relationship with the droplet transfer and arc ignition, and could reflect the variations of energy characteristics. The energy output characteristics of non-pulsed arc and pulsed arc during droplet transfer process are different. The matching of pulsed arc and pulsed droplet transfer mode obtains the best thermal and mechanical transfer characteristics, which is more suitable for the WAAM manufacturing process. No matter whether pulsed arc or non-pulsed arc is adopted, the energy output of arc should not be excessive, otherwise the energy output and the impact effect of arc and droplet transfer may be not conducive to the forming efficiency and quality of WAAM manufacturing.