Review of innovative strategies and future prospects in challenging-to-machine materials

Abstract Manufacturing industries increasingly use advanced materials such as high-strength alloys and superalloys, which, despite their superior performance, present significant machining challenges. This review highlights recent advances in machining these Challenging-to-machine materials (CMM), focusing on precision machining operations. Key innovations include enhanced tool life through composite materials, optimized geometries, and advanced cooling strategies such as minimal lubrication, cryogenic systems and hybrid approaches. Emerging techniques like oscillation-assisted and multi-process machining are also assessed. The analysis addresses tool–chip-workpiece interactions, surface quality, heat management, and sustainability, outlining current limitations and future research directions. The novelty of this work lies in proposing a unifying three-lever framework, namely thermal management, tool technology, and advanced/hybrid machining, applied consistently across four CMM classes, complemented by quantitative cross-comparison tables and a discussion of how these strategies align with sustainability and Industry 4.0 paradigms.