Abstract. Generally the study, evaluation and general understanding of end milling cutters are complicated by the complexity of the cutting process and of the cutting tool. The main performance factor of the end milling cutters is given by the durability of the tool. In practice the sound analysis of the tool engaged in the cutting process is used as a simple predictability mean to forecast the future durability of the tool. An alternative or complementary tool to predict future durability is the investigation of the chip behaviour. Chip behaviour investigations can also give clues concerning the possible improvement of the cutting tools. The current article presents a detailed chip behaviour investigation for 5-fluted end milling cutters with different performances and various geometries when approaching different types of metal cutting operations in 42CrMo4 alloy steel. Current study can be applied in future researches regarding the evaluation and the development of end milling cutters. Furthermore the current approach can be used on other types of cutting tools.

It's known that the durability of the cutting tool is influenced by the cutting parameters. In the recent years, scientists turn their research efforts to demonstrate that the microgeometry have an important role in determining the durability of the cutting tools. The processes studied most are milling and turning, but few researches have been done on the drilling operation. In this paper is presented the influence of 6.8 mm diameter drills with three values of the K-factor, but the same radius of the cutting edge and same macrogeometry. To obtain the desired microgeometry of the drills, two preparing technologies of the cutting edge were used. Drills were tested in two types of materials: X5CrNi18-10 (1.4301) and 42CrMo4 (1.7225). The main goal of this paper is to observe the influence of the microgeometry in the drilling process namely the durability and wear evolution.