A novel approach to use internally cooled cutting tools in dry metal cutting

Abstract

This paper presents a new cooling method to be used in dry metal cutting. This new cooling method is based on a tool holder with cooling fluid circulating inside a closed internal cooling system. A prototype that facilitates the cooling from inside the tool holder was specifically designed and manufactured. For this study, a series of cutting trials was carried out to investigate the practicality and effectiveness of the internally cooled cutting tool concept. Two techniques, one using a K-type thermocouple and the second using an infrared (IR) pyrometer, were employed to estimate the temperatures of the tool and the tool-chip interface. Experiments were conducted on DIN 1.2379 cold work die steel (50 HRC) using CVD-coated CNMG 190608-IC907 carbide inserts. The experimental results for dry cutting and for the internally cooled tool were compared using fluid dynamic analysis implemented via the ANSYS Fluent FEA code. The internally cooled tool exhibited the advantages of better surface roughness and extended tool life: in addition, machining was enabled at a wider range of cutting speeds while avoiding environmental hazards and health problems. The results clearly indicated that internal cooling could sufficiently reduce the cutting temperature and consequently, by controlling the critical cutting temperature, was able to circumvent it during the turning process. This technique could generally be advantageous for the machining of hard materials.