Size and shape of the liquid droplet at the molten tip of an arc electrode

Abstract

The main forces acting on the molten tip of an arc electrode are surface tension and electromagnetic force. Both of these forces depend on the shape of the droplet. Conversely, the shape of the droplet is determined by these forces. The equation to describe the shape of the droplet pending at the arc electrode is proposed and solved. This allows calculating the size of the detaching droplet significantly more accurately and over a wider current range compared to both existing models (stable force balance theory and pinch instability theory). Furthermore, the equation describes the main changes of the metal transfer as the arc current increases: slow decrease of the droplet size at low currents, sharp decrease at higher currents, and absence of the stable droplet above a certain current value. For higher currents a simple non-stationary model of the droplet development is proposed.