Abstract: Aiming at the dual bypass metal inert gas(MIG) welding process, pictures of the process of metal transfer under different bypass currents using the high speed camera is taken and the data of metal transfer by the image processing is obtained. The main forces affected the drop is calculated by the data. In addition, the situation of force under different welding parameters which act on the drop and researched the mechanism of metal transfer promoted are compared. The results indicated that electromagnetic force has the most important influence to the process of metal transfer of the dual bypass MIG welding. By the promoting of expand the area of arc root, the bypass arcs promote the metal transfer of the dual bypass MIG welding and this influence will be increased by bypass current. Moreover, with the increase of bypass current, the frequency of the metal transfer could be increased and the size of the drop is decreased when the total current is constant. The type of metal transfer is changed to spray transfer from globular transfer.

Key words: Dual bypass metal inert gas(MIG) welding, Force acting on droplets, Metal transfer