COOLING EFFECTS OF CUTTING FLUIDS ON CUTTING TOOLS

ABSTRACT Heat generation during machining operations significantly affects cutting tool performance, tool life, surface finish, and overall production efficiency. Excessive temperature at the tool–workpiece interface accelerates tool wear mechanisms such as flank wear, crater wear, thermal cracking, and oxidation, thereby increasing operational costs and reducing productivity. This study investigates the cooling effects of cutting fluids on cutting tools during turning operations using mild steel as the workpiece material and High-Speed Steel (HSS) as the cutting tool. An experimental research design was adopted to compare dry machining, water-soluble cutting fluid, and synthetic cutting fluid under controlled machining parameters (cutting speed of 150 m/min, feed rate of 0.25 mm/rev, and depth of cut of 1.0 mm). Temperature measurements were obtained using a K-type thermocouple and infrared thermometer, while tool wear was measured using a tool maker’s microscope. Surface roughness was also evaluated to determine machining quality. Results showed that dry machining recorded the highest temperature (400°C) and greatest tool wear (0.48 mm). The application of water-soluble cutting fluid reduced temperature by 36.25% and tool wear by 41.67%. Synthetic cutting fluid demonstrated superior performance, reducing temperature by 42.5% and tool wear by 54.17%, with an estimated tool life improvement of approximately two times compared to dry machining. Surface roughness improved significantly under wet machining conditions, with synthetic fluid producing the smoothest finish (1.9 µm). The study concludes that effective cooling significantly enhances tool life, reduces wear rate, and improves surface quality. Synthetic cutting fluid exhibited the best cooling-lubrication synergy among the tested fluids. The findings provide quantitative performance efficiency data and practical recommendations for optimizing cutting fluid application in machining operations.