Process Control Methods in Cold Wire Gas Metal Arc Additive Manufacturing

Abstract

Cold wire gas metal arc (CWGMA) additive manufacturing (AM) is more productive and beneficial than the common electric arc processes currently used in wire arc additive manufacturing (WAAM). Adding a non-energised wire to the gas metal arc (GMA) system makes it possible to overcome a process limitation and decouple the energy input from the material feed rate. Two novel process control methods were proposed, namely, arc power and travel speed control, which can keep the required geometry accuracy in WAAM through a broad range of thermal conditions. The reinforcement area of the bead is kept constant with accurate control over the height and width while still reducing the energy input to the substrate; decreasing penetration depth, remelting, and the heat-affected zone (HAZ); and reaching a dilution lower than 10%. This work also presents improved productivity compared to all the other single-arc energy-based processes with a demonstrator part built using 9.57 kg h−1 with CWGMA AM.

Evaluation of Melting Efficiency in Cold Wire Gas Metal Arc Welding Using 1020 Steel as Substrate

“…From Equation (10), when the Christensen number is plotted against the Rykalin number, the result will be a straight line with an angular coefficient numerically equal to the melting efficiency. This can be used to determine the melting efficiency over a range of Rykalin numbers, as in Figure 11.…”

“…One can determine an equation that schematically asserts that the Ch number is a function of the Ry number. The simplest equation with this dependence is Equation (10). Therefore, taking the derivatives in relation to Ry of the equations shown in Figure 11 for each process condition (thin and thick plate conditions) and taking the average between them, the average angular coefficient of these equations is numerically the estimate of melting efficiency.…”

“…Therefore, taking the derivatives in relation to Ry of the equations shown in Figure 11 for each process condition (thin and thick plate conditions) and taking the average between them, the average angular coefficient of these equations is numerically the estimate of melting efficiency. Since the coefficient of proportionality between the Ch and Ry numbers is the melting efficiency, it can be seen in Equation (10).…”

“…Cold wire gas metal arc welding (CW-GMAW) is a welding process derived from standard GMAW that aims to improve deposition rate (kg/h) while keeping the nominal heat input constant [9]. The process has shown some interesting properties, such as precise geometrical control during additive manufacturing and a reduction in dilution while achieving a deposition rate of 9.57 kg/h [10]. Moreover, the use of CW-GMAW reduces heat-induced distortion [11].…”

“…Among these is cold wire gas metal arc welding (CW-GMAW). This process has been successfully applied for wire arc additive manufacturing (WAAM) [10]; however, there is a scarcity of data regarding melting efficiency in the contemporary literature. The present work aims to determine the melting efficiency of CW-GMAW for the three natural transfer modes (short-circuit, globular, and spray) while welding plain carbon steel and determine the effect of plate thickness on melting efficiency.…”