Original Date: 07/18/1994
Revision Date: 01/18/2007
Information : Explosive Pressing Technology
A combination of capable facilities, an experienced engineering and operating staff, a commitment to continuous improvement, and process technology development has made the Mason & Hanger (M&H) explosive processing technology world class. Although originally constructed to provide the capability to pour TNT-based explosives into artillery shells, the Iowa Army Ammunition Plant (IAAAP) also maintained a limited explosive pressing capability for pellets, boosters, and leads needed for the artillery shells. In the 1950s, the Department of Energy (then the Atomic Energy Commission) established a pressed explosives line at the M&H run facility. When that operation moved in 1965, an experienced workforce and the facilities for pressing explosives remained at the Iowa facility. As munitions technology advanced, precision shaped charges and explosively-formed penetrator-type warheads became necessary to defeat multiple targets. These requirements for precision munitions were initially met by pressing oversize billets to the proper density and machining the explosive to final critical dimensions.
More recently, M&H has pioneered the development of plastic-bonded explosives pressing to net or near net dimensions. The company now maintains a unique and impressive capability built on more than 50 presses ranging in size from a 100-ton capacity to 800-ton capacity equipped with state-of-the-art process controllers, an experienced staff of tooling design engineers, process engineers and press operators, and experience with both traditional and new, insensitive explosives. Explosives are pressed in hydraulic presses to obtain a pressure of 20,000 psi on the explosive surface to obtain a charge that is 98% of maximum theoretical density and meets critical geometric requirements to tolerance as low as +.004-inch. A combination of SPC, improved tooling design, enhanced press control, and press cycle improvements have allowed M&H to consistently manufacture high quality explosive charges.
For example, continuous improvement activities have resulted in a doubling of the penetration performance of the Hellfire warhead while reducing the performance standard deviation by half. In the TOW 2B, the performance improvement has been almost 10% over the past three years. The process yields have also improved from 80-90% in the late 1980s to 98% for the period from 1989 through 1992 for the TOW 2A, thereby reducing scrap costs. The Hellfire scrap costs were reduced by 67% from 1989 to 1993.
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