Investigations on surface quality of helical gears finished by pulsed electrochemical honing

Abstract

Improvement in surface quality of helical gears is required to enhance their service life, operating performance and mechanical efficiency, and to reduce noise and transmission errors. Pulsed-electrochemical honing (PECH) is a fine finishing process hybridizing pulsed-electrochemical finishing (PECF) and mechanical honing. This work reports on improving the surface quality of 20MnCr5 alloy steel helical gears in terms of surface finish and microgeometry by studying effects of pulse-on time, pulse-off time, finishing time and voltage on them. The experiments were conducted using Taguchi L16 experimental design by varying the each input parameter at four levels. The results have shown improvements in the surface quality of the PECH-finished helical gears. Pulse-on time of 6 ms, pulse-off time of 3 ms, finishing time of 8 minutes and voltage of 16 V produced the best surface quality gear. The improvements in micro-geometry of helical gears in terms of average percentage improvement in total profile error, total lead error, cumulative pitch error, and in total runout were found as 41.3%, -23.2%, 74.7%, and 47.8%, respectively and the improvements in surface roughness of helical gears in terms of average percentage improvement in average surface roughness, maximum surface roughness and depth of surface roughness were found as41.6%, 32.3% and 39.6%. This work proves capability of PECH for finefinishing the helical gear flank surfaces simultaneously improving its microgeometry and surface finish.