Mechanical design and manufacture by powder technology of a new mandrel tool for the fabrication of assault rifle barrels

This paper presents a mechanical design procedure for the development of mandrel tools for barrels used in assault rifles by the application of powder technology. Besides, we also analyzed some considerations on its manufacturing process. In a first stage, the requirements that have to be fulfilled by the required tool were established. With these ideas, a conceptual design was obtained. Additionally, the Finite Element Method (FEM) was applied to analyze and determine the resultant stress field during the service manufacturing process. The experimental work complemented and validated the numerical analysis. For this purpose, 10 tools were manufactured. The first one failed after it had produced 505 gun barrels. The alignment of the hammer guides proved to be crucial. This situation was corrected and it was possible to obtain 2538 pieces with a second tool. In the third case, the sinterized material did not accomplish the demanded characteristics. Once, this situation was corrected, the other seven tools produced 1500 gun barrels in average. These factors improved the current manufacturing process that was followed with tools made for other materials and reduced the production costs. (C) 2012 Elsevier B.V. All rights reserved.