# Performance Investigation of Coated Carbide Tools in
## 2 Materials and Methods  
### Coated Cutting Tools and Workpiece  
The machining investigations of the present study were conducted via a tool holder of 63 mm external diameter and cemented carbide inserts of HW-K05/K20 ISO specifications using the DJET cutting insert WDMW080520 ZTR, as displayed in Figure 1a. The geometrical characteristics of the tool holder and the cemented carbide inserts are illustrated in Figure 1b. The chamfer length on the inserts' rake face measures approximately 280 \(\upmu\)m, while the cutting-edge radius is 20 \(\upmu\)m. Generally, chamfering on a carbide insert composes a critical design feature that enhances tool performance, durability, and machining quality in milling procedures [18]. In particular, chamfer geometries reinforce the cutting edge, making it less prone to chipping or breaking, especially during interrupted cuts or when machining hard materials. Furthermore, by strengthening the edge, the chamfer reduces wear and extends the lifespan of the insert, aiding in maintaining consistent performance over time, even under high-stress conditions. The flank wear VB was measured via an optical microscope, and typical results are exhibited in Figure 1c at various stages of the tool wear evolution. Regarding the mechanical properties of the coating and substrate, these were evaluated using an FEM-based analysis of the nanoindentation experimental process. The employed nanoindentation device was the Fischerscope H100 using a Vickers diamond pyramid. In order to minimize the impact of surface roughness on the indentation depth, 30 experiments per material investigation were conducted for stabilizing the moving average of the maximum indentation depth, as exhibited in Figure 2a. The estimation of the stress-strain curves of the investigated coating and its substrate was based on the 'SSCUBONI' (Stress-Strain CUrves Based on Nanoindentation) algorithm [19]. Particularly, the algorithm continuously simulates indenter penetration into the coating material and calculates the corresponding reaction force up to a maximum load of 15 mN as a function of penetration depth. Hereupon, the elastic modulus and stress-strain behavior of the material were determined by comparing the simulated force-depth relationship with the experimentally obtained indentation load-depth data. In addition, it should be noted that the plastic deformation of the coating was approximated using stepwise linear intervals in the stress-strain curve. The calculated stress-strain curves provided key material properties, including the elastic modulus (E), equivalent yield stress (S\({}_{\text{Y}}\)), and rupture stress (S\({}_{\text{M}}\)), as documented in Figure 2b. These properties were subsequently incorporated into the FEM simulations presented in Section 3.2. Figure 1: (**a**) Experimental setup; (**b**) Geometrical characteristics of the investigated milling cutter; (**c**) Characteristic tool wear evolution on the flank surface. Figure 2: (**a**) Nanoindentation analysis; (**b**) The corresponding material constitutive stress-strain laws of the examined coated insert and its substrate. In the present work, a modified AISI P20 steel that is equivalent to DIN 1.2311 steel was employed as the workpiece material, which is a pre-hardened mold steel with very good polishing and texturing properties that is widely used in applications that require high toughness, good polishability, and wear resistance [20]. Its balanced mechanical properties make it a popular choice for mold-making and tooling applications [21]. Specifically, AISI P20 is commonly utilized for plastic injection mold bases, cavities, and cores due to its good machinability, fatigue strength, high hardness, and reliability. It is also suited for producing automotive parts, consumer goods, and general constructional parts. Moreover, it is exploited in low-pressure die casting for non-ferrous metals such as aluminum, zinc, and magnesium, where moderate wear resistance is required.