OPTIMIZATION OF WELDING CYCLE TIME BY ESTABLISHING FULL GMAW PROCESS (STT AND P-GMAW) THROUGH A NEWLY DESIGNED SEMI-AUTOMATIC WELDING POSITIONER

Abstract

Alloy steel materials are predominantly used in the manufacturing of headers in thermal power plant boilers. Generally the hand hole pipe and dish end component are provided in the header for the inspecting the inner surface of the header. Conventionally the welding of dish end with hand hole pipe of the header is carried out using manual GTAW welding process for root pass and manual SAW welding process for filler passes which is a time consuming process. Thus it is substituted with a semi-automatic welding process i.e., STT-root pass followed by the pulsed GMAW for filler passes through a newly designed welding positioner. This semi-automatic welding process optimizes the cycle time and increases the productivity rate. Also the new welding process-STT and P-GMAW is established by following optimization technique of Taguchi's orthogonal array method and ensuring the weld quality performance through X-Radiography, mechanical tests impact test and hardness test.