A review on Cold Metal Transfer (CMT) technology of welding

Cold metal transfer (CMT) is a novel technique of joining, which is an improvised version of the gas metal arc welding (GMAW) techniques, in which the wire of the filler metal is deliberately pulled backwards after the short circuit. The retracted wire aids the disengagement of droplets during the short circuit, thereby transferring the metal into the pool of molten without the support of electromagnetic force. Due to this, the input of heat is greatly reduced and spatter is eliminated to greater extent. Lower volume of heat makes the technique of CMT welding a more ideal one for joining thin sheets and plates. Employment of CMT welding technique curtails spatter, distortion of joints and also requires limited clean up. CMT have made it possible to join together Al and steel. In addition to this, in this technique, the length of the arc can be monitored and can be controlled easily through mechanical means. Therefore, the stability of the arc is perfect, irrespective of the surface to be joined and during faster rate of joining, thereby making it possible to employ the technique of CMT welding in all position and for any application. This paper reviews in brief, the history, applications and principle of operation of the CMT welding technique. In addition to these, the several types of recently evolved types of CMT welding techniques namely CMT pulse advanced, CMT advanced, CMT + P, CMT Dynamic and the research findings of several relevant experimental works were discussed in brief.