# Wear Behavior of Uncoated and Coated Tools in Milling Operations of AMPCO (Cu-Be) Alloy
## 3 Results and Discussion
### Wear Analysis
#### 3.3.2 Tool Wear Mechanisms Analysis  
In this section, the identified wear mechanisms are presented. These were determined by performing SEM analyses for each of the tested tools. The main wear mechanism that was registered was adhesive wear, registering a built-up-edge, which was expected as the machined material is quite ductile.  
In Figure 14a, it is possible to identify the adhesive wear on an uncoated tool, with adhered material being registered on the tools' cutting edge. Chipping of the substrate  
Figure 12: Surface graph of the mean value of measured flank wear (VB) of the coated tools for each of the tested conditions.  
Figure 13: Comparison of the sustained flank wear of uncoated and coated tools for each of the machining conditions.  
is also registered. EDS analyses were carried out to determine the presence of adhered material, as seen in Figure 14b,c.  
The coated tools were also subject to adhesive damage, as can be observed in Figure 14, in the \(Z4\) area. In addition to the wear mechanism registered in the uncoated tools, these tool types suffered coating delamination, caused primarily by the adhesion of material to the tools' surface. Figure 15 shows that the tool suffered substrate exposure, as well as outer layer delamination, as seen in Z2, which corresponds to the intermediate CrN layer. EDS analysis carried out on this tool can be observed in Figure 16.  
In all the analyzed coated tools, delamination and erosion of the first DLC layer was registered, with this first layer being peeled off in the early stages of the machining tests (for cutting lengths of 18 m).  
Figure 17a,b presents the main wear mechanisms registered in the uncoated tools; more specifically, for uncoated tools tested at a cutting length of 48 m and feed rate values of 750 mm/min and 1500 mm/min. Once again, the presence of adhered material was found, that was deposited in the craters caused by machining. It can be observed that, for higher feed rate values, adhesive wear was more severe. In Figure 17b, it can be observed  
Figure 14: (**a**) Wear mechanisms present on an uncoated tools’ clearance face, tested at 36 m of cutting length and 750 mm/min feed rate; (**b**) EDS spectra of Z1; (**c**) EDS spectra of Z2.  
In Figure 18, a comparison of the wear mechanisms sustained by coated tools tested at a cutting length of 48 m for both feed rate values is shown. The main wear mechanisms that these coated tools suffered were coating delamination, adhesion, and tool chipping, for both feed rate conditions. However, for higher feed rate values, considerably more chipping damage to the tool was registered, as seen in Figure 18b, which negatively impacting the machined surface roughness. For lower feed rate values, the main mechanisms were adhesion, coating delamination, and chipping of the cutting edge.  
Figure 17: (**a**) Wear mechanisms registered on the rake face sustained by an uncoated tool tested at a cutting length of 48 m and 750 mm/min feed rate; (**b**) wear mechanisms registered on tools’ top sustained by an uncoated tool tested at a cutting length of 48 m and 1500 mm/min feed rate.  
Figure 18: SEM images of coated tools rake face tested at a cutting length of 48 m, at 220\(\times\) magnification: (**a**) for a coated tool tested at a feed rate value of 750 mm/min and (**b**) coated tool tested at a feed rate value of 1500 mm/min.  
A discussion of these results cannot be performed due to the absence of results reported for these kinds of alloys.