Preamble - Physics and capabilities of gas metal arc welding

摘要

Gas metal arc welding (GMAW) has been established as a widely used method for joining. An electric arc burns between the tip of a wire fed as a consumable electrode and the work piece typically operated as cathode. The arc heating melts the wire tip as well as the work piece forming the weld pool and causing the droplet transfer from the wire to the weld pool. In pulsed GMAW statistically one droplet per pulse should be detached, and this method has been proven to realize a quite regular and defined material transfer. Increasing demands on joining technology arise from new materials, complex products and the request for a highly efficient and reliable production. This even requires a continuous adaption and improvement of welding processes. Present trends in the development aim improved weld seam quality, higher welding speed and the transfer to partly or fully automated processing. Concepts of process control, e.g. control of the power transfer, are of particular interest for new applications of arc welding, among others in competition with the laser welding technology. Previous developments in these directions were characterised by empirical methods to a large extent, supported by view scientific studies. It has been estimated, that present challenges of the arc welding technology can be met by highly innovative concepts only. This requires systematic scientific investigations of the process aimed in considerably improved understanding of the basics of physical mechanisms. And this should be done in close interaction with the solution of actual problems in arc welding.