NMWR-9-2815-220 Overhaul Manual for M60 M88 Engine AVDS-1790-2CA, AVDS-1790-2DA, AVDS-1790-2DR Download

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NMWR 9-2815-220 CRANKCASE ASSEMBLY OVERHAUL—Continued 0006 00 RECLAMATION – Continued NOTE To demonstrate proficiency and attain certified status, an operator shall flame spray a test piece in accordance with this specification which shall be destructively and metallographically examined to assure bond integrity and coating soundness. To maintain certified status, an operator must consistently produce acceptable repairs relative to the flame sprayed coating and pass a yearly destructive examination for bond and coating integrity. (a) Degrease block ensuring all grease, dirt, and rust is removed from saddle areas. Bevel all sharp edges. (b) Wash all areas to be metalsprayed using Metco Solvent. (c) Mask cap mating area and areas between saddles with Thermospray Mask Material, 0.010 – 0.020 in. (0.254 – 0.508 mm) thick copper, brass, or sheet steel and Metco Anti-Bond. (d) Plug oil holes with graphite plugs and grit blast bearing saddle areas to be metalsprayed using G25 angular steel grit at 60 psi. (e) Preheat saddle area to approximately 200° F (93° C) using 6P thermospray gun. (f) Apply Metco 445 Self-Bonding Aluminum Bronze Composite Powder adhering to MIL-STD-1687A(1) using Metco 6P Thermospray System. Undercutting is not necessary as material can be finished to a feather edge. Allow 0.010 – 0.050 in. (0.254 – 1.27 mm) for finishing. (1) Spray angle should be as close to 90 degrees to substrate surface as practical. (2) Use parameters as packed with material, giving special attention to the spray distance. (3) Block may be sprayed in vertical or horizontal position. (g) Seal coating while hot, using Metco 185 Sealer to improve machining. (h) Machining is done dry with either line boring, line honing, or horizontal boring machines using feeds and speeds normally used for machining cast iron. Use 883 grade carboly tool bit or equivalent square tool with 1/32 in. (0.7620 mm) radius, set at 45 degree angle to part. Keep tool sharp and machine using the following parameters: Surface work speed 600 ft./min. Traverse speed 0.002 – 0.004 in. per revolution Infeed 0.010 in. per side, rough cut 0.005 in. per side, finish cut NOTE Quality control will inspect finished part to insure adherence to this procedure. (i) All mounting surfaces repaired by this process shall be 100% inspected for coating integrity after machining. The coating shall show no bond separation at the coating to base metal interface. The coating shall be free from blistering, cracking, chipping, and frayed edges. There shall be no bleedout of oil or other contaminants through the finished coating. 0006 00-7 Change 1