Investigation of flank wear behaviours of CBN cutting tool in hard turning hardened AISI 4140 steel by using different cutting parameters through real-time monitoring system

In this study it was aimed to determine the cutting tool edge abrasion of the hardened AISI 4140 (52 – 54 HRC) steel materials commonly used in the production of machine elements such as shaft, axle and pin in the industry in turning with cutting tools coated with CBN (Cubic Boron Nitride) using different cutting speeds and feed rates. Cutting tool edge abrasion affects both the life of the cutting tool and size precision of the machine part, the production of which is realized. Unpredictable rate of abrasions in the cutting tool during the cutting process negatively affects the surface characteristics and dimensional measurements of the part produced. Determination of the abrasion occurring in the cutting tool during the cutting process and replacement of the cutting tool when the abrasion occurring on the tool reaches acceptable limits are quite important in terms of providing the surface quality and size precision of the machine element produced and also in terms of determining the life of the cutting tool. Abrasions occurring in the cutting tool during the cutting process, dimensions of the abraded areas occurring on the cutting tool at the phase when the cutting process is stopped at certain intervals are determined with the aid of a microscope. Changes (change in the processed part size, change in the current drawn by the bench, change in the forces acting on the cutting tool, etc.) related to the abrasion occurring in the cutting tool during the cutting process are monitored during the process without interrupting the cutting process and cutting tool abrasion is indirectly determined. In indirect measurement, determining the tool abrasion without stopping the bench during the cutting process has advantages over direct measurement with respect to the production speed and the quality of the surface characteristics. During the turning of the hardened AISI 4140 materials, changes occurring in the processed part size based on the abrasion in the cutting edge were determined using On-line monitoring method. In these tests, cutting parameters consisting of 200 and 280 m/min cutting speed, 0.04, 0.08, 0.12 mm/rev feed rate and 0.2 mm cutting depth were utilized.