Determination of process parameters of pulsed GMAW

Abstract

The pinch instability theory (PIT) is applied to calculate the detaching drop size and time in the spray mode, which occurs in Multi drop one pulse (MDOP) condition. The PIT calculates the critical wavelength of current-conducting liquid cylinder in closed-form equation of current, surface tension and wire diameter and the molten tip of wire is assumed as the infinite cylinder of uniform radius. The predicted results show considerable discrepancy with the experimental data. The PIT is modified in this work to simulate drop transfer by deriving the critical wavelength of the modified PIT, which includes the effective cylinder radius, finite cylinder geometry and current leakage. The effects of the modifications on drop transfer are analyzed and the predicted results of the modified PIT are compared with experimental data. Force displacement model (FDM) is applied to predict the effects of power source response characteristics on drop transfer and process parameters of one-drop one-pulse (ODOP) condition are calculated assuming the rectangular, trapezoidal and modified waveform. The predicted results show reasonable agreement with the available experimental data.