Comparative Study on Thermal Behaviour, Tool Wear and Surface Roughness in Milling EN8 Steel for Sustainable...

Area of Science:

• Materials Science
• Manufacturing Engineering
• Tribology

Background:

• Dry machining is crucial for sustainable manufacturing but faces challenges like tool wear and thermal instability.
• Medium-carbon steels, such as EN8, are widely used, necessitating efficient machining strategies.

Purpose of the Study:

• To evaluate the kinematic-tribological performance of EN8 steel during dry milling.
• To compare up-milling and down-milling strategies for optimizing tool life and surface finish.

Main Methods:

• Utilized response surface methodology (RSM) with a central composite design (CCD) for 36 experimental runs.
• Investigated the interactions of spindle speed, feed rate, and depth of cut.
• Employed Grey Relational Analysis (GRA) to determine multi-objective optimal cutting parameters.

Main Results:

• Down-milling demonstrated superior performance, yielding 12.4% less tool wear, a 45.9% better surface finish, and a 47 °C lower peak cutting temperature.
• Attributed down-milling's advantages to favorable chip formation kinematics, reduced entry friction, and enhanced heat dissipation.
• Identified optimal parameters for down-milling: mid-range cutting speed (22.31 m/min) and low feed rate (25 mm/min).

Conclusions:

• Down-milling offers significant kinematic-tribological benefits over up-milling for dry machining of EN8 steel.
• A kinematic-tribological coupling exists, providing a unified approach for optimizing dry machining processes.
• The findings offer a practical strategy for enhancing the efficiency and sustainability of machining harder materials.