A Multi-Objective optimization framework for the sustainable machining of Monel 400

Area of Science:

• Materials Science
• Manufacturing Engineering
• Tribology

Background:

• Superalloys like Monel 400 present significant machining challenges due to their high strength and toughness.
• Optimizing machining processes is crucial for industries such as aerospace and precision manufacturing to reduce costs and improve efficiency.

Purpose of the Study:

• To investigate the combined effects of lubrication and cooling on the machinability of Monel 400.
• To compare the performance of different machining environments: dry cutting, Minimum Quantity Lubrication (MQL), Cryogenic CO₂, and a hybrid MQL + CO₂ approach.
• To identify optimal machining parameters for enhanced Monel 400 machinability.

Main Methods:

• Comparative machining assessment across four environments: dry, MQL, Cryogenic CO₂, and hybrid MQL + CO₂.
• Scanning Electron Microscopy (SEM) for analyzing tool wear mechanisms (adhesion and abrasion).
• Analysis of Variance (ANOVA) to determine the influence of machining parameters (feed, cutting speed, depth of cut).
• Multi-Objective Response Surface Methodology (MORSM) to establish optimal machining conditions.

Main Results:

• The hybrid MQL + CO₂ method demonstrated superior performance, reducing cutting force by 19.58%, tool wear by 19.10%, and surface roughness by 47.19% compared to dry cutting.
• SEM analysis confirmed adhesion and abrasion as primary wear mechanisms, influenced by temperature and hard particle interactions.
• ANOVA indicated feed and cutting speed as the most critical parameters affecting machining outcomes.
• Optimal conditions identified: 78.35 m/min cutting speed, 0.1 mm/rev feed, and 1 mm depth of cut, achieving a composite desirability of 0.84.

Conclusions:

• The hybrid MQL + CO₂ machining strategy offers a sustainable and effective method for improving Monel 400 machinability.
• Understanding wear mechanisms and optimizing parameters are key to enhancing the performance and efficiency of machining challenging superalloys.
• The findings provide a practical framework for optimizing Monel 400 machining in demanding industrial applications.