Cryogenic Cooling in Sustainable Machining: A Review on Advancements and Applications for Difficult-to-Machine Materials

Abstract In recent years, the manufacturing industry has increasingly emphasized sustainable machining practices to mitigate environmental pollution and enhance operator safety. One of the sustainable techniques widely explored in the past few years is cryogenic cooling. Cryogenic cooling has emerged as a highly effective and environmentally benign alternative. The application of liquid nitrogen (LN2) as a cryogenic coolant significantly influences tool performance and process efficiency by reducing the temperature at the tool–chip–workpiece interface, improving dimensional accuracy, minimizing tool wear, decreasing cutting forces, and enhancing surface integrity. This paper primarily reviews previous and current research articles on cryogenic cooling techniques in machining operations, including turning, milling, drilling, and grinding, for various difficult-to-machine materials such as titanium alloys, nickel-based alloys, hardened steels, stainless steels, ceramics, and composites. The discussion highlights the limitations of conventional cutting fluids, challenges encountered during the machining of these materials, and the comparative performance of LN2 and LCO2 cooling systems. The outcomes from reviewed studies reveal that cryogenic cooling substantially improves machinability, chip breakability, and surface quality while reducing thermal and mechanical loads on the cutting tool. Furthermore, the paper identifies recent advances in hybrid cryogenic approaches and outlines potential future research directions to enhance the sustainability and industrial adaptability of cryogenic machining systems.