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High precision liner manufacturing using exotic metals for enhanced shaped charge jet performance.

Description:

TECHNOLOGY AREA(S): Weapons

OBJECTIVE:

To develop high precision metal forming/liner manufacturing capabilities for liner manufacturing surge capacity and to enable more cost competitive government loading, fabrication, and testing of developmental shaped charge and explosively formed penetrator warheads using hard to machine, exotic materials.

DESCRIPTION:

Manufacturing of metal liners for explosively formed penetrators and shaped charges can be a complicated and time-consuming process to do with the required precision. There are generally two phases of this process, manufacturing the preforms from raw material, billets, plate, or sheet, and machining the preforms to the desired shape. There are only about 4-5 companies that currently do this in the entire continental Unites States.


To manufacture liner preforms for large diameter liners, heavy forges are necessary to forge billets of raw material into near net shape preformed blanks. For smaller applications, deep drawing operations may be used and although somewhat less complicated than the heavy-duty forges required to manufacture larger liners, still require specialized skill and expertise to produce high tolerance, precision parts necessary to achieve high performance warheads.


Precision liner machining requires not only extremely high precision and tolerance, often around .0005 inch for a liner that may be 6 inches or greater in diameter, but unique expertise in machining all surfaces of somewhat conical shaped liners in addition to warhead loading techniques. Shaped charge liners are generally manufactured using vacuum fixtures that allow precise location and machining of each of the surfaces. Through wall thickness, liner profile, transverse wall thicknesses, and surface finish requirements all require extreme precision. Finally, specialized skill at machining exotic materials is often required. These types of materials may either have high densities, e.g. greater than 10 g/cc and may be as high as approximately 19 g/cc. Some of these exotic materials may also be pyrophoric in nature and may require machining under specialized fluids with particular feed and speed rates for safety purposes.

PHASE I:

The objectives of phase I are for the liner manufacturer to evaluate 1) whether they currently have the capability to manufacture precision liners to government specified tolerances 2) if they do not currently possess this ability, to calculate the feasibility and cost of procuring all necessary hardware, including ancillary fixtures and devices, in order to stand this capability up. The final, and most important objective of this effort would be to provide an estimated unit production cost, based on machining delivered preforms for a typical quantity of liners, materials, and geometries so that the government could measure their cost against larger, more traditional liner manufacturers. Their findings will be documented in a final report and shall include plans, if warranted, for continuing into Phase II.

PHASE II:

In phase II the contractor will either begin manufacturing the necessary ancillary hardware determined previously in phase I or they will procure the hardware if the government determines that it is warranted and cost effective. After this, they will then manufacture a limited number of liners, up to approximately 12 liners of 3 different designs for comparison to known metallurgy, geometric tolerance, and ultimately performance against baseline charges.

PHASE III:

If an additional source of cost competitive, high quality liner manufacturing can be developed, there are a variety of systems to which this technology might be transferred. These include, but are not limited to, TOW2A/B, Hellfire, Javelin, DPICM, and shoulder fired systems among others.

KEYWORDS: shaped charge liner, liner materials, liner manufacturing, explosively formed penetrator liner, high precision machining, dense metal machining

References:

1. Walters, W.P., Zukas, J. A., "Fundamentals of Shaped Charges" Wiley-Interscience, January 1989.

2. Buc, Steven M. "Shaped Charge Liner Materials: Resources, Processes, Properties, Costs, and Applications. February 1991.

3. Walters, William. "A Brief History of Shaped Charges" ARL-RP-232, December 2008.

4. Singh, M., Bola, M.S., Prakash, S., "Determination fo Dynamic Tensile Strength of Metals from Jet Break-Up Studies" 19th International Symposium on Ballistics, 7-11 May 2001, Switzerland.

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