TM-9-2350-277-20-4 Unit Maintenance Manual Volume 4 M113A3 M577A3 M1064A3 M1068A3 M58 Download

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TM 9-2350-277-20-4 REPAIR HULL BY WELDING — Continued 0529 00 7. When welding unequal sections, direct arc against heavier piece to fuse the two edges evenly. Watch weld pool edge rather than arc to make sure weld pool edges fuse right. 8. When performing multi-pass welding, make sure edges of weld pool fuse right. Watch weld pool rather than arc. Any oscillating or weaving motion should be slight, smooth, and slow. Brush material with clean, stainless steel wire brush after each pass. On small weldments, lower amperage slightly after each pass if welding members become too hot. 9. Clean up weld area and touch-up paint all bare metal (see TM 43-0139). 10. Install any parts removed for access. MIG WELDING METHOD 1. MIG (Gas Metal Arc Welding) 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 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 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. 0529 00-5 Change 3