process, casting finishing processes and machining of the rough cast- ing resulted in an approved finished component 110 days from the Army’s order date.
The deflector tray is both
structural and functional. The tray guides a new projectile into the cannon’s breech and deflects the spent casing into a holding area after the projectile is fired through the barrel. Due to force and surface wear, a steel alloy is required. Steel castings are renowned for struc- tural toughness in severe service applications but also notorious for difficulty in meeting cosmetic and dimensional requirements within a reasonable lead time. Because of their high yield strength, high material stiffness and tolerance of deflection without damage, steel castings also can be effective in lightweight applications. Pushing the limits of minimum as-cast wall thickness is important in reducing weight in this type of application. H.A. Burrow Pattern Works
(HAB), Silesia, Mont., collaborated with the American Metalcasting Consortium (AMC) sponsored by the Defense Logistics Agency (DLA), the Army’s Research, Development & Engineering Command (RDE- COM), Benet Laboratory at Waterv- liet Arsenal, Watervliet, N.Y., Acme Castings, Huntington Park, Calif., and the Steel Founders’ Society of America (SFSA) to convert an origi- nal 15-piece fabricated steel design to a one-piece, lightweight 19.5-lb. cast steel design.
The 15-piece fabrication was difficult and expensive to manu-
facture and had an unacceptably high rejection rate. One of the first decisions in the new design was to choose a different steel alloy, because the carbon steel used for the fabrication would not be a good casting candidate due to fluidity issues in the thin 0.08-in.
wall sections. HAB determined an investment cast 17-4 PH alloy in H1100 condition had the fluid- ity and strength to be a good cast substitute. After numerous solid model
iterations, additional features previously welded to the fabricated
The tray casting guides the projectile into the cannon’s breech.
February 2014 MODERN CASTING | 43
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84