Multi Response Optimization for Internal Surface Finish of Inconel 625 tubes in MAF and CMAF processes using desirability Function Approach

With the rapid development of industrial technology, various innovative alloys and materials have been developed. Of these, the nickel-based superalloys have emerged as very important materials because of their excellent mechanical and thermal properties, which are highly useful in critical applications in marine, solar, petrochemical and aerospace industries. For the aforementioned applications, it is important for the internal surface finish of Inconel 625 tubes to be improved to ensure performance reliability. The precision finishing methods will have to be optimized to obtain the desired surface quality. The process enhancement of Magnetic Abrasive Finishing (MAF) and chemically assisted Magnetic Abrasive Finishing (CMAF) processes is discussed in this research using a multi-response optimization approach. The Desirability Function Approach (DFA) was used in conjunction with experiments which were designed using Response Surface Methodology (RSM) to study Percentage Improvement in Surface Finish (PISF). Two regression models - predictive MAF model and predictive CMAF model - were generated. The optimal processing parameters determined by DFA of 56 minutes of processing time, 25% concentration of abrasive, and 270 RPM of rotational speed, gave promising results. The average PISF was validated to be about 60% for MAF and 72% for CMAF, respectively, showing that CMAF provides 20% higher finishing efficiency as compared to MAF. In addition, the microstructural surface changes were studied using the Scanning Electron Microscopy (SEM) technique. The results showed that compared with MAF, the CMAF process achieved a smoother surface with lower scratch depth and lower waviness, indicating that the CMAF process was superior to MAF for improving the surface formed on the inside of the tube.