Investigation of the Machinability Characteristics Using Dry Electrostatic Cooling (DEC) for the Turning Process of SCr420H

Abstract

This study presents the first comprehensive investigation of the machinability characteristics and tribological mechanisms of Dry Electrostatic Cooling (DEC) during turning of SCr420H steel. DEC represents a novel eco-friendly machining approach utilizing ozone generated through high-voltage discharge as an alternative to conventional cutting fluids, offering potential solutions to the economic, health, and environmental challenges of traditional lubrication methods. Unlike conventional cooling methods relying on physical heat removal, DEC operates through unique chemical interactions. EDS and XPS analyses confirmed the formation of iron oxides including Fe2O3 and Fe3O4 on the work surface. This oxide formation led to a significant 74.8% reduction in surface hardness and a 47.1% decrease in friction coefficient compared to the bare specimen. These favorable changes translated into substantial performance improvements during actual machining operations. DEC reduced the resultant cutting force by up to 12.1% and tool wear by up to 38.5%, depending on machining parameters. Surface quality improvements exhibited distinct patterns relative to cutting speed, with Ra values showing the most significant reduction (24.2%) at lower cutting speeds, while Rz values decreased substantially (20.2%) at higher cutting speeds. Chip cross-section analysis revealed that the friction coefficient under DEC conditions was 42% lower than under dry machining, with reduced plastic deformation. These improvements stem from two mechanisms: the oxide layer acts as a solid lubricant reducing friction, while the decreased surface hardness allows more efficient plastic deformation. Given SCr420H's extensive automotive applications, these findings demonstrate significant potential for advancing sustainable manufacturing practices.