Simultaneous optimization of machining parameters for dimensional instability control in aero gas turbine components made of Inconel 718 alloy

Aero gas turbine components made of Inconel 718 superalloy revealed signifi cant dimensional instability after machining. The dimensional instability i s a manifestation of alterations in residual stresses and microstructure, w hich are influenced by machining parameters. This paper presents a simultan eous optimization technique used to control the dimensional instability in turning operation. Empirical equations are established for predicting surfa ce residual stresses, surface finish, dimensional instability and tool life using response surface methodology. Experimental results show a strong cor relation between residual stresses and dimensional instability. A desirabil ity function approach is used to optimize the multiple responses and machin ing parameters are derived for practical applications. Inconel 718 test spe cimen and jet engine components machined with optimal cutting parameters sh ow dimensional instability within the acceptable tolerance band [S1087-1357 (00)01704-4].