TM-9-2350-261-20-3 Unit Maintenance Manual Volume 3 M113A2 M577A2 M1064 M1068 M1059 M901A1 Download
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REPAIR HULL BY WELDING — Continued MIG WELDING METHOD 1. MIG (Metal Inert Gas) uses a dc power source, control panel, and welding gun. The gun feeds a consumable bare electrode at a given rate into a molten pool beneath a blanket of inert gas. When an arc is struck, a molten pool forms at once. Move the welding gun along the joint line at a rate that shapes the right size bead. The covering of inert gas keeps air from polluting the weld zone. No flux is needed. 2. Lead angle and cant angle are important. Place gun at a lead angle of 10 to 15 degrees off vertical. Point gun in direction of weld travel for good gas coverage, cleaning, and preheating of material. Place gun at cant angle of 90 degrees to parent metal so filler wire and arc are directed toward apex of groove. This will give equal fusion to both sides of material, even weld buildup, and equal penetration. 3. Keep nozzle clearance of 1/2 to 5/8 inch (12 to 16 mm) for good gas coverage. Wrong nozzle clearance will cause the following: a. Oxide deposits in the weld bead. b. Force gas bubbles into the weld. c. Prevent cleaning action on the material in front of the weld pool. 0575 00-5 0575 00 TM 9-2350-261-20-3