Optimization of welding current waveform parameters in controlled short circuiting transfer GMAW

For controlled short circuiting transfer GMAW, peak current I_ap, background arcing current I_ab and tail-out time t_w (time required for welding current to decrease from I_ap to I_ab) are the adjustable waveform parameters, which have significant influence on the process stability, spatter rate and weld appearance. Using orthogonal experiment method, waveform parameters were optimized at different wire feeding rate. The results show that peak welding current has the strongest influence among the three waveform parameters. At wire feeding rate of 320 cm/min, the spatter rate is more than 2.5%, the weld appearance is always rough and bad no matter what levels of the waveforms parameters were used. With the wire feeding rate varying from 360 to 400 cm/min, the optimal waveform parameters keep constant, i. e. I_pa=440 A, I_ba=50 A, and t_w=0.6 ms. At wire feedingrate of 400 cm/min, the stable welding process with a spatter rate of less than 0.35% and excellent weld appearance can be achieved in quite wide ranges of waveform parameters(I_pa is 440-480 A, I_ba is 30-50 A, and t_w is 0.6-0.8 ms).