Modeling and Experimental Validation of Droplet Size in Gas Metal Arc Welding Process

Abstract

The dynamics of capillary jet instability is a complex but interesting problem because of its uses, if we observe gas metal arc welding (GMAW) process, it’s about the jet of molten steel interacting with both electric field and magnetic field. Since GMAW was introduced in the early of last century, it has become one of the most popular welding methods. Its efficiency and flexibility is great; different modes of transfer can be employed for different uses. There are about four ways to analyze mass transfer happening in GMAW; these methods help us to optimize droplet size of GMAW process according to the users. Numerical solution to this problem takes a long computational time, so the objective of this work was to model GMAW through bond graph in order to save time and increase the frame-work for multi-domain modeling in bond graph. Two Theories are prevalent in analyzing GMAW drop size, static Force balance method (SFBM) and pinch instability theory (PIT). Both of the theories have their advantages and disadvantages as they have completely different underlying phenomenon. SFBM predicts the radius a little bit higher than the experimental values; however PIT needs the exact nature of disturbance. Pinch instability theory is used here to model GMAW metal transfer dynamics in bond graph. By this approach, break-up time is the function of the axial displacement of molten metal, amplitude and wave number of disturbances. Process is also simulated in commercial software package FLUENT™ and the results are validated with experimental and bond graph results.