TM-9-2350-261-20-3
CARRIER, M113A2, M577A2, M1064, M1068, M1059 AND M901A1
TECHNICAL MANUAL; UNIT MAINTENANCE MANUAL - VOLUME 3 OF 4
TM-9-2350-261-20-3 - Page 595 of 932
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.
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TM 9-2350-261-20-3
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