## 2 Datasets Description and Preparation  
Turning is a process to remove material, which is mainly oriented to metal machining. Within this field, several criteria are used to establish the conditions for an acceptable turning process, including surface roughness, measurement tolerance, power consumption, machining time, forces, loads, etc. These measurement criteria are highly related to the selected cutting insert, cutting parameters, working material and working conditions [25]. A cutting insert varies according to its geometry, shape and material composition. Thus, it is possible to apply a specific group of cutting inserts to a specific turning application, working material and working conditions. In general, a tool-insert can be defined by its geometrical features and material composition, which are hereinafter referred as tool-insert features. The most notable tool-insert features are the inscribed circle (ICmm), clearance angle (AN), cutting length (LEmm), corner radius (REmm), thickness (Smm) and shape angle (SC), as shown in Figure 1.  
The ICmm is a tool-insert feature that is highly related to the insert size. A large insert size increases the stability performance but oversizing can lead to high production costs. This feature must be linked with the depth of the cut, the entering angle and the cutting length to be used. The AN is the angle between the front face of the insert and the vertical axis of the workpiece [25]. This feature also defines the negative or positive quality of an insert [25]. On the other hand, the REmm feature is also related to the chip-breaking and cutting forces but it is mainly linked to finished surfaces. For a set feed rate cutting parameter, the machining yields a certain surface roughness. Furthermore, the radial forces that push away the insert in the turning machining become the axial forces as the depth of the cut increases with respect to the radius nose. As a suggestion from the supplier, the depth of cut should be greater or equal to 2/3 of the nose radius of the tool-insert [25]. The insert-shape feature is the most tangible feature, which is mainly selected by accessibility requirements. This feature defines a tool-holder and the depth of cut range in the process. The SC feature is defined by the nose angle of the tool-insert, which is related to strength and reliability issues. Large nose angles are stronger but require more machining power. They also increase the vibration tendency of the machine. On the contrary, small nose angles are weaker and have small cutting edges but are linked to better surface roughness [25]. The CTPT feature, which describes the cutting operation, is defined by three possible configurations: Finishing, Medium and Roughing operations. The WEP feature is a logical feature, which defines if the tool insert has a wiper radius. The GRADE feature describes the material composition of a tool-insert. Three features are linked to different grade features. These features describe the distribution of each grade in the range of area applications for ISO group materials. Figure 1: Tool-insert features considered in this study [25]; cutting length (LEmm); corner radius (REmm); thickness (Smm); and shape angle (SC). The introduced features are MC_L (machine condition low), MC_H (machine condition high) and MC_Suitability (machine condition suitability). The MC_L and MC_H features represent the low and high borders of each grade in the range of area application. The MC_Suitability feature is defined as a percentage of range for each grade that belongs to wear resistance region, which is in the upper region of the total field of application. For instance, the grade 4325 is defined as MC_L = 40, MC_H = 10 and MC_Suitability = 50%; the grade 5015 is defined as MC_L = 0, MC_H = 20 and MC_Suitability = 100%; and the grade GC30 is defined as MC_L = 35, MC_H = 45 and MC_Suitability = 0% [25]. Figure 2 graphically shows the relation between the working material (hardness feature), cutting parameters (feed rate) and cutting velocity.