Electrochemical micromachining of uniformly tapered needles for endodontic application

In the present work, electrochemical micromachining (ECMM) was utilized to fabricate uniformly tapered Nitinol needles for endodontic application. A novel dynamic drawing method with stepwise voltage increments was employed to achieve precise uniform tapering during the ECMM process. To better investigate the effect of feed rate, specimen length, duty ratio, and electrolyte concentration on the full taper angle of the tapered needle, an in-house setup of an ECMM was developed. The feed rate had the highest influence (26.35%). Experimental findings verified the designed taper angles for each specimen length to ensure uniform tapering of the fabricated needles. Regression analysis identified optimal parameters: feed rate of 0.32 μm/sec, duty ratio of 21.37%, specimen length of 5.93 mm, and electrolyte concentration of 2.49 M. Validation tests confirmed the reliability of the proposed ECMM process with a novel approach, achieving a minimal error of 1.17%, making it suitable for endodontic applications.