Purpose:

All Department of Defense (DoD) military services use a 2.75-inch rocket system. Procurements of more than 1,000,000 rockets are planned through the Future Year Defense Plan. The conventional batch method planned for those rocket propellant grains produces large amounts of waste propellant, nitroglycerine, and process water and is labor intensive. This project seeks to demonstrate a lower cost manufacturing process that reduces the amount of waste and pollution generated in the manufacture of the MK 90 double base propellant grain used in the MK 66 2.75-inch rocket system. The new process utilizes a continuous shear roll mill and twin screw mixer/extruder and can reduce the propellant scrap, nitroglycerine emissions, and touch labor while increasing safety by utilizing remote control technology.

Description:

This program is utilizing novel processing techniques to reduce the amount of waste and emissions generated in the conventional manufacturing of 2.75-inch rocket motor grains. The new process uses a shear roll mill to manufacture solventless double base propellant pellets that provides a feedstock to a twin screw mixer/extruder. The Indian Head Division, Naval Surface Warfare Center will be performing the twin screw extrusion process development and demonstration in close collaboration with Alliant Techsystems, Inc., which is performing the shear roll mill process development and demonstration. The Army Research, Development, and Engineering Center will implement the process, develop model-based control schemes, and conduct an independent environmental and cost audit. The new manufacturing process will be evaluated relative to the conventional batch process for acceptable product performance, minimum environmental impact, and low manufacturing cost. The merits of the new continuous process will be assessed by characterizing and comparing the product manufactured and comparing the amount of waste and toxic air pollutants generated by the twin screw process to the conventional batch process, and validating the cost reduction of the new technology. Standard propellant characterization tests will be used to compare the twin screw and conventional batch products. Similarly, the propellant grains manufactured by each process will be tested in identical configurations and under identical test conditions to determine ballistic performance. A detailed mass balance on both processes will document the waste and air emission reduction. ARDEC will develop a shear roll mill process model and conduct an independent environmental and cost audit.

Benefits:

Continuous twin screw processing is a revolutionary lower cost technology for the manufacture of a variety of energetic materials. These lower manufacturing costs are realized as a result of reduced environmental costs, improved operating efficiency, flexible manufacturing capabilities, and enhanced operator safety. This technology is expected to save the DoD $24 million over a 5-year period. A preliminary life-cycle analysis concluded that this technology will result in a reduction of 785,000 pounds of propellant waste, 9,500,000 gallons of wastewater, 115,000 pounds of toxic air emissions, and 31,500 pound of lead contaminated ash. (Anticipated Project Completion - 2005)

Contact:

Mr. Stuart Richman
Indian Head Division, Naval Surface Warfare Center
Code 2330C
101 Strauss Avenue
Indian Head, MD 20640
Telephone: (301) 744-6463
Fax: (301) 744-4843
E-mail: richmansa@ih.navy.mil