A Study on the Efficacy of Hard Turning (HT) Process in Enhancing the Surface Reliability by White Layer Elimination Using CBN Inserts Under Protective Gas Mixture Atmosphere

S. Girisankar ； M. Omkumar

《中國機械工程學刊》 39卷2期 (2018/04) Pp. 233-244

摘要

Of late, Hard Turning (HT) process has established itself as a feasible alternative to the traditional grinding, due to its ability to facilitate precise machining with better surface finish along with its capability to offer a dry or near dry machining for super hardened steels. However, parts made out of the Hard Turning crops adverse surface pattern known as ＂White Layer＂ (WL), which results in poor surface reliability. Hence, this study was focused on the hard turning performed under Argon-CO_2 protective gas mixture atmosphere. Since this gas mixture provides more heat sink at the Thermally Mechanically Affected Zone (TMAZ) during the hard turning process carried out with CBN inserts The innate qualities of this gas mixture excellently curbed the mechanisms which are responsible for the White Layer formation, by ensuring greater heat dissipation by vaporization, regulating uniform cooling through convection and efficiently protecting the machined surface against the environmental reactions. Recently conducted study and their noteworthy results, have for sure established the significant role of this abundantly available and harmless Argon-CO_2 gas mixture, in enhancing the surface reliability by the effective elimination of White Layer formation.

關鍵字

Hard turning ； Protective gas mixture atmosphere ； Super hardened steels ； Surface reliability ； White Layer