FY series of semi-automatic welding of carbon dioxide to protect, apply to the plate after plate of the all-position welding and spot welding work fast, low-welded steel, low-alloy steel structure, high-strength low-alloy steel, stainless steel, steel, paste, copper, Aluminum, nickel and so on. Local into one structure, wire feeder circuit PWM modulation, wire feeding power, to ensure an effective process of welding wire feeding degree of stability.