Study on Technology and Performance of 3D Printed Special‐Shaped Grain

ABSTRACT In view of the challenges of high safety risk and difficult molding faced by traditional energetic material molding technology in manufacturing complex structure grain, 3D direct‐ink writing printing technology was adopted to realize high precision and mold‐free molding of HMX‐based special‐shaped booster grain. Through rheological control, it is determined that the energetic slurry with 90% solid content has the optimal pseudoplastic fluid characteristics, and has good fluidity and formability. The extrusion process was simulated by ANSYS Polyflow module, and it was revealed that the beveled needle has the advantages of small pressure drop and stable flow rate, and the needle diameter and driving air pressure are the key factors to control extrusion expansion. By optimizing the process parameters, it is concluded that the best molding effect can be obtained when the beveled needle is 0.84 mm, the driving air pressure is 62052.82 Pa (9 Psi) and the printing speed is 8–12 mm/s. Performance tests show that the printed annular, conical annular, and external conical concave spherical special‐shaped charges have precise and micro‐uniform structures, density of 1.638–1.647 g/cm 3 , detonation velocity of 7493–7542 m/s, thermal stability of which is significantly improved by 24.5% compared with HMX raw material, and all of them can reliably propagate detonation. This study confirms that 3D direct writing printing technology provides an effective solution for safe, efficient, and high‐performance manufacturing of complex energetic charges.