Effect of Cryogenic Heat-Treated Honing Gears on Surface Quality Improvement of Bevel Gears in P-ECH Process

In this paper, bevel gears made of 20MnCr5 alloy steel are finished using pulse electrochemical honing (P-ECH) process. The honing gears used during finishing process were made of same material, which obtained higher hardness than the workpieces through two distinct heat treatments. The two different heat treatments viz. (i) case hardening through a carburizing process (CP) alone, and (ii) a combination of CP followed by deep cryogenic treatment (DCT), (referred to as CP_DCT) were utilised to improve the surface characteristics of the honing gears. These honing gears were used in P-ECH process for finishing workpiece bevel gears. The experimental results indicates that the hardness of honing gears is crucial factor in improving surface quality of the workpiece bevel gears. Surface quality of workpiece bevel gears was assessed in terms of surface finish. The results show that, honing gears underwent through CP_DCT improves the surface roughness of workpiece gears by over 50% compared to those processed with CP alone. The enhancement will increase the service life and operating performance, reducing noise levels and the chances of premature failures of the finished bevel gears.