Process stability for GTAW-based additive manufacturing

Abstract: Purpose: Traditional gas tungsten arc welding (GTAW) and GTAW-based wire and arc additive manufacturing (WAAM) are notably different. These differences are crucial to the process stability and surface quality in GTAW WAAM. This paper addresses special characteristics and the process control method of GTAW WAAM. The purpose of this paper is to improve the process stability with sensor information fusion in omnidirectional GTAW WAAM process. Design/methodology/approach: A wire feed strategy is proposed to achieve an omnidirectional GTAW WAAM process. Thus, a model of welding voltage with welding current and arc length is established. An automatic control system fit to the entire GTAW WAAM process is established using both welding voltage and welding current. The effect of several types of commonly used controllers is examined. To assess the validity of this system, an arc length step experiment, various wire feed speed experiments and a square sample experiment were performed. Findings: The research findings show that the resented wire feed strategy and arc length control system can effectively guarantee the stability of the GTAW WAAM process. Originality/value: This paper tries to make a foundation work to achieve omnidirectional welding and process stability of GTAW WAAM through wire feed geometry analysis and sensor information fusion control model. The proposed wire feed strategy is implementable and practical, and a novel sensor fusion control method has been developed in the study for varying current GTAW WAAM process.