###### Abstract  
In this paper, a practical issue of the application of cubic boron nitride (CBN) cutting tools for the machining of steel 100 Cr6 thin-walled bearing rings is addressed. Three geometries of the commercially available CBN cutting inserts were tested at different machining parameters. The effect of geometry was assessed in terms of surface integrity, considering 2D profile parameters, 3D topography of the surface, and residual stresses in the surface layer. The results were sometimes contradictory, since the same cutting inserts provided the largest and the lowest values of the topography parameters, dependent on different cutting conditions. In general, CBN cutting inserts with XCEL geometry ensured the smallest profile parameters \(Ra\) and \(Rz\), and the spatial parameters of \(Smr1\) exhibited the largest values among all tested tools, suggesting reduced wear resistance. Residual stresses analysis did not reveal any inacceptable or potentially dangerous surface layer state after machining. surface integrity; steel 100 Cr6; CBN; cutting tool; cutting speed; cutting feed; cutting depth; bearing rings +
Footnote †: journal: Applicid  
**C****e**  
**The Effect of Cutting Tool Geometry on Surface Integrity: A Case Study of CBN Tools and the Inner Surface of Bearing Rings**  
hardness and heat-resistant alloys to fabricate various components such as shafts, bearings, gears, engine blocks, etc., with high dimensional accuracy and surface parameters using high cutting speed [3]. The wear resistance and durability of other cutting tool materials can reach only 50%, and after certain modifications it can be improved, but still reach no more than 75% of CBN tools wear resistance [4]. There are extensive studies published on the morphology of the CBN structure and its effect on cutting tool wear resistance [5; 6; 7]. Other studies analyzed the effect of various additions and binders in CBN composites [8]. Since some materials, such as compacted graphite iron, cause extensive wear of CBN tools, [PERSON] et al. published the results of their investigations on CBN tool wear with different metalworking fluids [9]. In an assessment of the tool life, surface integrity was found useful both in terms of the machined surface [10] and the surface of the cutting insert [11]. It is widely known that the performance of a machined component, including features such as fatigue strength, wear resistance, and tribological behavior, is closely correlated with the surface integrity obtained by machining. In general, the integrity of a machined surface is described as the relation of its mechanical, chemical, metallurgical, and topographical state to its functional characteristics [12]. A study on the cutting tool load effect on the machined surface aimed to statistically evaluate the real dynamic loads in correlation with surface roughness after milling [13]. [PERSON] and his team analyzed the effect of a chosen milling strategy on the surface quality after the pocket milling process [14]. [PERSON] et al. demonstrated that the ultrasonic assisted cutting process, compared with conventional machining, had the potential to improve the quality of a surface machined with CBN tools [15]. Specifically, [PERSON] and [PERSON] [16] investigated the influence of tool cutting edge geometry on the surface roughness in the finish hard turning of AISI 52100 steel. They found that the two-factor interaction between the workpiece hardness and cutting edge geometry had a substantial effect on the obtained surface roughness. It was also reported that after machining with large edge hone tools, deeper, more compressive residual stresses appeared in comparison with the ones after hone tools with small edges or chamfered tools [17]. Moreover, when harder materials underwent machining with chamfered tools, an increase in both the axial and the circumferential residual stresses has been reported for increased cutting speeds [18]. [PERSON] et al.