Investigations on micro-geometry improvement of straight bevel gears finished by electrochemical honing process

Abstract

This paper reports on investigations on micro-geometry improvement of the straight bevel gears by finishing them by electrochemical honing (ECH) process. Adjacent pitch error, cumulative pitch error, and total runout have been used to evaluate the micro-geometry of the case hardened straight bevel gears made of 20MnCr5 alloy steel. An innovative experimental setup was developed for finishing the entire face width of bevel gears without requiring any reciprocating motion to workpiece gear or cathode gears and simultaneously maintaining the required inter-electrode gap by envisaging a novel concept of complementary cathode gears. Experiments were conducted to study the influence of five ECH parameters (concentration, temperature and flow rate of electrolyte, applied voltage, and rotary speed of workpiece gear) on the micro-geometry of the bevel gears using Taguchi L27 orthogonal array. Results showed that certain combinations of the ECH parameters appreciably improved the micro-geometry of the bevel gears, i.e., the quality of the bevel gear improved from standard DIN 9 to DIN 8 for the single pitch error, from standard DIN 8 to DIN 7 for the adjacent pitch error, and from DIN 7 to DIN 6 for the total runout within an optimized finishing time of 2 min which will ensure improved tribological performance and service life of the bevel gears. This work proves that ECH has great potential to be developed as a technologically better, productive, and economical alternative to the conventional bevel gear finishing processes.