The presented work deals with the development of a novel TIG hot-wire process for the additive manufacturing of metallic components, which, in contrast to previous arc processes, enables a significant increase in melting performance with simultaneously reduced heat input. This is achieved by means of an upstream resistance heating of the wire between two contact points within the hot wire feeding system. The torch, hot wire feeder and gas nozzle are designed in such a way that a constant bead geometry can be guaranteed regardless of the machining direction. On the one hand, this can improve the dimensional accuracy; on the other hand, an increase in productivity is achieved through a significant reduction of process times. Essential parts of the work include the simulation-supported development of the processing system, the design and implementation of an innovative process control system and the testing of the new technology.

Gas metal arc welding (GMAW) processes are used in a wide range of applications due to their high productivity and flexibility. Nevertheless, the supplied melting wire electrode leads to a coupling of material and heat input. Therefore, an increase of the melting rate correlates with an increase of the heat input by the arc at the same time. A possibility to separate material and heat input is to use an additional wire, which reduces penetration and worsens the wetting behaviour. Consequently, bead irregularities such as bonding defects or insufficient root weldings can occur. In the context of this article, a controlling system for a two-dimensional magnetic arc deflection is presented, which allows to influence arc position as well as material transfer. The analysed GMAW hot wire process is characterised by high melting rates while also realising a sufficient penetration depth and wetting behaviour.Keywords Gas metal arc welding . Hotwire . Two-dimensional magnetic arc deflection . High productive welding

In this publication, the different metal transfer modes of a hot-wire GTAW process with indirect resistive preheating of the wire are presented. The hot-wire GTAW process is characterized by an additional preheating unit that is used to heat the wire before it reaches the melt pool. Thus, to preheat the wire, the contact between the melt pool and the wire is not necessary. In order to examine the metal transfer of the wire, deposition welds are analysed using a high-speed camera with a laser light source as well as a data acquisition unit. The presented results comprise the impact analysis of the GTAW current, the hot-wire current, the wire feeding rate, the wire feeding angle as well as the wire feeding direction. The observed metal transfer modes can be characterized as either a constant melting bridge (cmb) between the wire and the melt pool or a recurring melting bridge (rmb). The analysis also reveals that the influence of the process parameters and thus the metal transfer mode on the bead properties is only marginal.