Cutting fluid plays a pivotal role in CNC machining, contributing to both process efficiency and the quality of the finished part through several key functions. One of its primary roles is cooling: during machining, friction between the cutting tool and workpiece generates significant heat, which can reach temperatures exceeding 500°C. Cutting fluid absorbs and dissipates this heat, preventing thermal damage to the workpiece—such as warping in metals like aluminum or steel—and reducing tool wear caused by high temperatures. This cooling effect is particularly critical for high-speed machining, where heat buildup is more pronounced. Lubrication is another essential function; cutting fluid forms a protective film between the tool’s cutting edge and the workpiece, reducing friction and minimizing adhesion of workpiece material to the tool (a phenomenon known as built-up edge, or BUE). BUE can degrade surface finish and cause tool chipping, so effective lubrication helps maintain sharp cutting edges and improves surface quality. Additionally, cutting fluid flushes away chips and debris from the cutting zone, preventing them from recontacting the tool or workpiece, which could cause scratches, dimensional inaccuracies, or even tool breakage. Different types of cutting fluids are used based on the application: water-soluble coolants are effective for high-heat operations like milling steel, while straight oils (mineral or synthetic) provide superior lubrication for heavy-duty machining of materials like titanium. Proper maintenance of cutting fluid—including monitoring concentration, pH levels, and filtering to remove contaminants—ensures it remains effective over time. Without adequate cutting fluid, CNC machining processes would suffer from increased tool wear, poor surface finish, higher scrap rates, and longer cycle times, making it an indispensable component of effective machining operations.