Subtractive manufacturing is a fundamental process that involves the strategic removal of material from a workpiece to shape, refine, or create a desired product. By employing a diverse range of techniques such as milling, drilling, turning, grinding, and electrical discharge machining (EDM), subtractive manufacturing achieves exceptional precision and intricacy. This is accomplished by starting with a larger raw material and systematically removing excess material to achieve the final form. The subtractive approach allows for the creation of highly complex components with extremely tight tolerances, making it an indispensable process across multiple industries, including automotive, aerospace, healthcare, and consumer electronics. Among the various subtractive manufacturing processes, CNC milling and drilling are the most widely utilized techniques across industries. The preservation and continuous monitoring of cutting tools in a computerized numerical control (CNC) machine are crucial for ensuring a seamless transition in the manufacturing workflow while maintaining consistent part quality. The implementation of tool condition monitoring (TCM) in milling operations for specific classes of materials is a significant step in this direction, as it provides essential data on tool life, wear, and part quality. By leveraging real-time monitoring, manufacturers can enhance efficiency, prolong tool longevity, and improve machining precision. The primary goal of this research is to monitor the health and performance of subtractive machining tools using tool condition monitoring methods across a diverse range of machining processes, materials, and applications. The first area of focus is on milling operations involving materials with low to high yield strength. This study investigates how tool condition monitoring can be optimized for machining operations spanning a broad spectrum of material strengths. Through advanced real-time data analysis and monitoring techniques, the research aims to enhance the efficiency, durability, and accuracy of milling processes for a variety of materials. The second domain of this research explores specialized medical applications, specifically the drilling of synthetic bone. By implementing tool condition monitoring tailored to surgical drilling procedures, this study aims to optimize operations involving synthetic bone, ensuring precise, controlled, and safe drilling. This objective underscores the critical role of tool condition monitoring in the healthcare sector, where enhanced surgical precision can improve patient outcomes and minimize procedural risks. Finally, it is essential to evaluate the environmental implications of subtractive manufacturing approaches. The third research objective focuses on the use of diamond-coated cutting tools, analyzing both tool condition monitoring and the associated environmental impacts. This perspective integrates an in-depth performance assessment of diamond-coated tools with a broader evaluation of their environmental footprint. By examining sustainable tooling solutions, this research aims to highlight the environmental considerations of advanced tooling technologies, paving the way for more eco-conscious manufacturing practices. Through these three focal areas, this research provides a comprehensive understanding of tool condition monitoring across different machining operations, material types, and applications. The insights gained will contribute to improved tool efficiency, prolonged tool life, enhanced manufacturing precision, and sustainable machining solutions across multiple industries.