Experimental Evaluation of Machinability of Monel 400 Alloy During High Speed Micro Milling Using Various Tool Coatings

Abstract

Quality of finished miniature products is characterized by surface roughness as well as burr formation after manufacturing processes. It gains more significance when it is gauged in terms of high precision and dimensional accuracy of final micro parts. The requirement of complex fea-tures in 3D micro parts also figures out its significance. Similarly, tool wear is an important indicator of production efficiency and quality related to finished parts. In the current research, the impact of key input parameters like depth of cut, feed rate, cutting speed and various tool coatings (TiAlN, TiSiN, nACo, including an uncoated tool) were statistically analyzed while carrying out micro-milling of Monel 400 super alloy. Sur-face roughness along with burr formation and tool wear were considered as response parameters due to their significant nature. Machining ex-periments were performed up to 80,000 rpm (high-speed range). Feed rate values were selected in comparison with cutting tool edge radius. The selected values of feed rate were taken into consideration at moderate and high-speed ranges while selecting the values equal to below and above the values of cutting-edge radius. Digital microscopy and scanning electron microscope (SEM) were utilized for analysis in addition to statistical techniques for response parameters. Methodology utilizes Taguchi's Experimental design. L16 orthogonal array was formulated to carry out mi-cro milling experiments on Monel 400 specimen, having dimensions 20mm x 30mm x 40mm. Contribution ratio (CR) of individual input pa-rameter was calculated through Analysis of Variance (ANOVA). The outcome of experimental work indicated that feed rate was the most sig-nificant factor for surface roughness with CR 27.86%. It also became most significant factor for top burr width in both categories (Up-milling & down-milling) with CR 56.56% and 56.60% respectively. Moreover, it was also most significant factor for top burr height in both categories (Up-milling & down-milling) with CR 23.84% and CR 28.47% respectively. Whereas in case of tool wear, the depth of cut and tool coatings were significant factors with CR 19.46% and 28.47% respectively.

Keywords

• micro millin
• monel 400 alloy
• manufacturing processes
• taguchi design of experiments
• process design
• sustainability
• green manufacturing
• precision machining