Avaliação das potencialidades do processo CMT PIN em diferentes materiais

Abstract

The search for manufacturing processes improvement is continuous in the mechanical construction general industry. In this sense, existing processes are improved and others created or derived. This is the case of the CMT PIN process, devised from the MIG/MAG CMT (Cold Metal Transfer) welding, which is capable of depositing short and thin metallic pins also in metallic base materials. Because it is a relatively recent development, the CMT PIN process does not appear to have many industrial applications, and there is no consistent information on its capability to deposit pins in different materials and possible effects of such deposition on base metal mechanical properties. Thus, this work aims to improve the understanding of the CMT PIN process and verify its application in thin sheets of carbon steel, galvanized steel and aluminum, specifically assessing the effects of process parameters on the pin formation stages, and on the distortion and mechanical strength of the base material. Different combinations of height and number of pins and thickness of the base material were evaluated, always with cylindrical-headed pins. The study of the pin deposition stages was based on the voltage and current signals and resultant power of the process and considering images obtained by high-speed filming. The evaluation of the distortion of the sheets was carried out by measurement of flatness before and after the deposition of pins. The effect of the deposition of the pins on the mechanical strength of the sheets was verified by ultimate tensile strength and elongation values obtained from tensile tests and complemented by metallographic evaluation of the joint area between pin and base material. The CMT PIN process proved to be quite repetitive for all evaluated combinations. Changes in the height of the deposited pins and thickness of the sheets in general did not cause high distortion or compromise the mechanical properties of the assessed base materials, except the aluminum that was more sensitive to the presence of pins.