Abstract An investigation was raising the question: "What does 'arc length' mean?" Actually, it is considered expressing a kind of natural relationship between arc voltage and arc column shape. Statements such as "The higher the voltage the longer the arc" or "The arc voltage proves approximately proportional to the arc length", are frequently noticed in this conjunction. However, the author suggests that there is no general possibility of describing 'arc length' over the whole welding process range. Instances are represented in this paper, showing both theoretical attempts of definition and practical observations. This paper intends to contribute to a serious discussion of something trivial, indeed very well-known or used among welding experts, but actually yet hardly understood, at least as when it comes to closer examination

Resumo Gas Tungsten Arc Welding (GTAW) é um processo bem conhecido por proporcionar alta qualidade da solda mas juntas com menor desempenho. Por isto o Gas Metal Arc Welding (GMAW) é frequentemente escolhido para aumentar a produtividade, considerando que a qualidade é também amplamente aceitável. Segmentos da indústria, especialmente àqueles que requerem a produção de revestimentos resistentes à corrosão com alta qualidade, por exemplo, aplicando material de enchimento à base de níquel, estão regularmente sob consistente demanda para atender os critérios "zero defeito". Neste contexto, limitações na soldagem podem ser superadas com o emprego de sistemas avançados GTAW 'arame-quente'. Este artigo, sob a perspectiva da automação da soldagem, descreve a tecnologia de tais sistemas e apresenta o estado da arte nesse campo – principalmente quanto a aplicação do revestimento por GTAW com dois cátodos e arame quente, que amplia consideravelmente os limites alcançáveis do processo.

Abstract Gas Shielded Tungsten Arc Welding (GTAW) – a process well-known providing highest quality weld results joined though by lower performance. Gas Metal Arc Welding (GMAW) is frequently chosen to increase productivity along with broadly accepted quality. Those industry segments, especially required to produce high quality corrosion resistant weld surfacing e.g. applying nickel base filler materials, are regularly in consistent demand to comply with "zero defect" criteria. In this conjunction weld performance limitations are overcome employing advanced 'hot-wire' GTAW systems. This paper, from a Welding Automation perspective, describes the technology of such devices and deals with the current status is this field – namely the application of dual-cathode hot-wire electrode GTAW cladding; considerably broadening achievable limits.