Effect of finishing time and electrolyte composition on geometric accuracy and surface finish of straight bevel gears in ECH process

• Novel concept of twin complementary cathode gears for bevel gear finishing by ECH.
• Study of electrolyte composition & finishing time effects on microgeometry & finish.
• 75% NaNo3 + 25% NaCl and 2 min finishing time gave best improvement in the responses.
• Significant improvement in the geometric accuracy and surface finish of bevel gears.
• ECH can be economical and productive alternative finishing process for bevel gears.

This paper presents study on the effects of electrolyte composition and finishing time on geometric accuracy and surface finish of straight bevel gears by electrochemical honing (ECH) process with an objective to improve their service life and operating performance. An experimental setup was developed for fine finishing of straight bevel gears by ECH using an innovative concept of twin complementary cathode gears. It ensured finishing the entire face width of the bevel gears without any reciprocating motion and maintained the required inter-electrode gap (IEG). Gravimetric aqueous solution of NaCl and NaNO3 was used as the electrolyte. Geometric accuracy was evaluated in terms of errors in pitch and runout while surface finish was evaluated by average and maximum surface roughness values. An electrolyte composition having 75% NaNO3 and 25% NaCl and finishing time of 2 min were found as the optimum combination. The results have shown considerable improvement in geometric accuracy and surface finish of the bevel gears. It proves the capability of ECH to improve the quality of the bevel gears of any material hardness with high productivity.