TM-9-2350-247-20-3 Unit Maintenance Manual Volume 3 M548A1 M548A3 Tracked Cargo Carrier Download
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TM 9-2350-247-20-3 REPAIR HULL BY WELDING — Continued 0406 00 WARNING Welding on foam-filled parts is PROHIBITED. Toxic fumes can result in death. 10. Do not weld or use too much heat in areas or carrier where sealing compound (WP 0542 00, Item 33), (WP 0542 00, Item 36), or (WP 0542 00, Item 38) has been applied or is known to exist. If you must weld in these areas, remove com pound, then clean area w ith cleaning com pou nd (W P 0542 00, Item 9). A fter weld ing, apply new sealing compoun d (WP 0542 00, Item 33), (W P 05 42 00 , Item 36 ), or (WP 0 542 0 0, I tem 3 8). a. Foam-filled parts: Driver’s compartment doors. MAGNESIUM CASTING, FILING, AND GRINDING WARNING Do not use water or foam-type extinguishers. These types of extinguishers will intensify a magnesium fire. 1. Observe special safety precautions when filing or grinding magnesium castings. Fine particles of magnesium are a fire hazard. See page 0406 00-2 f or a list o f magnesium castings used on this carrier. U se the following precautions when working with or near magnesium. a. Use grinding equipment marked FOR MAGNESIUM GRINDING ONLY. b. Do not allow magnesium dust or magnesium dust mixtures to accumulate. Keep area clean. c. Keep tools used to work magnesium sharp. d. Dispose of grinding sludge immediately. e. Wear leather or smooth, fire-retardant clothing; brush frequently. f. Keep fire extinguisher for magnesium handy. MIG WELDING METHOD 1 . MIG ( Metal I nert Gas) Weldin g. This p rocess uses a dc po wer source, control p anel, and a w elding gun. The gun feeds a consumable bare electrode at a given rate into a molten pool beneath a blanket of protective inert gas. When an arc is set up, 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. Contraction and Expansion. Aluminum welds contract about 6 percent in volume when they become solid after being melted. Welding at a slow speed may cause too much heating of the area around weld. This will cause the metal to expand too much. It will then shrink too much when it cools. 3. Filler wire: a. Always use clean wire. Filler wire polluted by grease, oil, dust, or shop fumes causes porous welds. b. After welding, cover wire to prevent pollution. 0406 00-4 Change 1