Numerical Study of Coolant Flow Phenomena and Heat Transfer at the Cutting-Edge of Twist Drill

Abstract

Cutting tool coolant channels play a pivotal role in machining processes, facilitating the efficient supply of cooling agents to high-stress areas and effective heat dissipation. Achieving optimal cooling at the tool’s cutting-edge is essential for enhancing production processes. Experimental investigations into tribological stress analysis can be limited in accessing complex tool–workpiece contact zones, prompting the use of numerical modelling to explore fluid dynamics and tribology. In this study, the coolant flow dynamics and heat dissipation in drilling operations were comprehensively investigated through computational fluid dynamics (CFD) modelling. Four twist drill models with varying coolant channel arrangements were studied: standard model drill, standard model drill with notch, profile model drill, and profile model drill with notch. Two distinct approaches are applied to the coolant inlet to assess the impact of operating conditions on fluid flow and heat dissipation at the cutting-edge. The findings emphasize that cutting-edge zones have insufficient coolant supply, particularly in modified drill models such as the standard model drill with notch and profile model drills with and without notch. Moreover, enhanced coolant supply at the cutting-edge is achieved under high-pressure inlet conditions. The standard model drill with a notch exhibited exceptional performance in reducing thermal load, facilitating efficient coolant escape to the flute for improved heat dissipation at the cutting-edge. Despite challenges like dead zones in profile models, the standard-with-notch model yielded the most promising results. Further analyses under constant pressure conditions at 40 and 60 bar exhibited enhanced fluid flow rates, particularly at the cutting-edge, leading to improved heat dissipation. The temperature distribution along the cutting-edge and outer corner demonstrated a decrease as the pressure increased. This study underscores the critical role of both coolant channel design and inlet pressure in optimizing coolant flow dynamics and heat transfer during drilling operations. The findings provide valuable insights for designing and enhancing coolant systems in machining processes, emphasizing the significance of not only coolant channel geometry but also inlet pressure for effective heat dissipation and enhanced tool performance.

Keywords

• drilling
• CFD
• coolant
• heat dissipation
• internal cooling channel design