Е-Публикации
Технически университет - София

Abstract: This study focuses on the optimisation of critical technological parameters in the Electro-Chemical Rifling (ECR) process for the manufacturing of barrels for under-barrel grenade launchers. A full-factorial experimental design (2³) was employed to examine the influence of current (I ≈ 950 A), voltage (U ≈ 7 V), pressure (P ≈ 22 bar), and processing time (T ≈ 176 s) on the resulting surface roughness. Rifling was performed using graphite electrodes with sodium chloride (NaCl) or sodium nitrate (NaNO₃) electrolytes under controlled conditions. Surface roughness was measured at five evenly spaced positions along the rifled bore. The process was optimised to consistently achieve a target roughness of Ra = 0.8 µm, which was adopted as a technological threshold for ensuring adhesion of subsequent coatings. Statistical analysis, including Student’s t-test and Fisher’s F-test, confirmed the validity and reliability of the developed model. The optimised parameters were successfully implemented in industrial-scale production, establishing a stable and validated process window for ECR. The developed approach enables precise control over surface characteristics, contributing to improved mechanical and tribological performance of the barrels. These findings demonstrate both the practical applicability of the method and its potential for adaptation in other Electrochemical Machining (ECM) technologies within the defence industry.

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