Wear Behavior of TiAlN/DLC Coating on Tools in Milling Copper–Beryllium Alloy AMPCOLOY® 83

Abstract

In recent years, the exponential growth of the machining industry and its needs has driven the development of new manufacturing technologies, more advanced cutting tool types, and new types of coatings to extend tool lifespan. New coating solutions have been studied and implemented for machining tools, which provide a low friction coefficient and lubrication, thus increasing tool lifespan. Following this line of reasoning, it is relevant to develop scientific work aimed at studying the behavior of cutting tools coated with thin films that promote low friction and high lubrication, as is the case with DLC (diamond-like carbon) coatings. These coatings promote good resistance to oxidation and allow high machining speeds, properties also exhibited by TiAlN (titanium aluminum nitride) coatings. In fact, there is a gap in the literature studying the performance of cemented carbide tools provided with multilayered coatings in milling operations of Cu–Be alloys, commonly used in inserts of plastic injection molds. This study’s objective was to investigate the effect of a multilayer coating (TiAlN/DLC) on end-milling tools to analyze their cutting performance when milling a Cu–Be alloy known commercially as AMPCOLOY^®83. The quality of the machined surface was evaluated, and the wear of the cutting tool was studied. A comparative analysis of milling parameters with respect to their effect on the condition of the surface after machining and the resulting wear on the tools, using coated and uncoated tools and different machining parameters, allowed us to verify a better quality of the machined surface and wear quantified in approximately half when used coated tools.

1. Introduction

Machining continues to be one of the most common processes for producing components for the most diverse industrial sectors. The significant growth in additive manufacturing processes has not taken away machining’s prominence, as it is still quite difficult to compete with different machining processes in terms of dimensional accuracy [1]. The importance of the process can also be assessed by the density of studies that are published annually, including several states of the art that bring together hundreds of recent articles [2,3]. Studies on machining are dispersed across several topics, from the kinematics and rigidity of equipment [4,5], to the investigation of tools [6], and increasingly include very current concerns, such as the impact of machining on the environment [7,8]. Although the initial investment in equipment weighs on costs, tools represent an important direct cost in machining. Furthermore, premature tool wear leads to greater resource consumption and the generation of more waste [9]. Therefore, it is vitally important to improve the behavior of tools, both from an economic and environmental perspective [10]. These concerns are particularly relevant when the materials to be machined are difficult to cut or with high a tendency to adhere to the tool.

There is little literature in terms of machining Cu–Be alloys, but these alloys are increasingly used in the manufacture of inserts for plastic injection molds because their incorporation increases the durability of the molds, as well as improving their precision, also benefiting the quality of surface polishing, which allows injected products to be obtained with greater shine and general quality [11]. In fact, the combination of Cu and Be brings some very useful attributes for that type of application. Cu contributes adequate mechanical strength, high thermal conductivity, dimensional stability, and resistance to oxidation and wear [12]. In turn, Be is characterized by its high hardness [13]. This characteristic property of Be presents additional challenges in obtaining highly polished surfaces as currently required by injected parts, because of the abrasive nature of these hard particles, which significantly increases the wear of the cutting edges when machining the cavities of the inserts commonly used in plastic injection molds, increasing the costs and complexity associated with production and repair operations [14,15]. Another undeniable advantage of these alloys in the production of inserts for mold cavities is the possibility of quickly draining the heat brought by the injected plastic material, allowing faster cooling of the injected material, which can translate into an effective reduction in injection cycle time by 80% [16]. This economic advantage, associated with the patented surface quality of these inserts, makes the use of Cu–Be alloys very attractive in the mold industry. The most common Cu–Be alloys are C17510, which has high thermal conductivity but moderate hardness, and C17200, which has good conductivity and high hardness [17,18]. The latter are the most suitable for mold cavities, as they allow for greater mold longevity without maintenance operations, presenting a very interesting level of conductivity considering the application. The C17200 Cu–Be alloys are detailed in ASTM B 194-15, Standard Specification for Copper–Beryllium Alloy Plate, Strip, Sheet, and Rolled Bar [19], and their use is widespread across numerous applications. Sharma et al. [20] studied the influence of hard Be particles during machining with diamond tools. This study allowed us to verify that when the cutting edge encounters a hard Be particle, depending on the positioning of the particle relative to the cutting plane as well as the size of that same particle, it tends to tear it off, leaving the corresponding dig. On the other hand, the tool suffers corresponding wear. Another study conducted by Sharma et al. [21] allowed us to conclude that the hard Be particles were mainly responsible for tool wear and that the thrust forces are approximately one order higher in the turning of Cu–Be alloys when compared to the same operation in Cu. It was also possible to verify that atomic stress was the main cause of phase transformation in the diamond tool, as well as the occurrence of high interface temperatures. Sharma et al. [22] concluded the same effect in a similar work, referring again to the abrasive effect of the Be hard phases. Sharma et al. [23] found in another similar work that, for the same cutting length, the roughness was around 48% higher in Cu–Be alloys compared to Cu alloys. Analyses carried out using molecular dynamics simulation made it possible to observe that hard precipitate particles are subject to cracking, which propagates in different directions. As the tool moves from the Cu-rich phase to the Be-rich phase, the cutting mechanism undergoes a ductile-to-brittle transition. It was also possible to observe that the Cu and Cu–Be surfaces machined with diamond inserts were contaminated by C and Cu oxides. Similar results were also published by Sharma and Kumar [24], corroborating the same phenomena previously reported. Zuo et al. [25] investigated the milling process of the C17200 alloy, concluding that, on the one hand, the microstructures observed on the surface of the machined part suggested that the process of generation and detachment of sticky substances on the tool surface is positively correlated with the partial removal of the Co binder and the accumulation of sticky substances. On the other hand, taking into account the energy spectrum analysis and the cutting conditions, the adhesive effect appears to have a positive relationship with tool performance, both in terms of friction between the tool and the workpiece and wear resistance. This phenomenon allows us to understand that the high adhesion rate can be induced by tool wear, including delamination of the coating and poor lubrication in the contact zones. Also, in milling operations using AMPCOLLOY 83, Sousa et al. [26] concluded that for short machining distances, WC-CO tools coated by PVD with a DLC/CrN multilayer coating showed less wear and better-machined surface quality, but for longer cutting distances, uncoated WC-Co tools showed better behavior, both through a lower roughness measured on the workpiece surface and a lower wear rate. Nogueira et al. [27] also tested WC-Co-uncoated and PVD-coated tools in milling AMPCO alloy but using a different coating: TiAlTaN. The wear phenomena identified were different regarding the uncoated and coated tools. The coated tools were essentially affected by the delamination of the films, followed by chipping on the tool substrate and the observation of some abrasion scratches. Regarding uncoated tools, which generally performed better than coated tools, they revealed abrasion and adhesion phenomena, essentially due to the hard Be particles (abrasion) and the traditional softness of Cu. The authors also found that the surface roughness of the machined part is strongly affected by the feed rate and cutting length; when these parameters are increased, there is an evident degradation in surface quality. Sudhakar et al. [28] found that the Cu–2Be alloy presents relatively higher mechanical properties when machined under cooling and lubrication conditions in comparison to dry-cutting conditions.

In terms of the machinations of this alloy, the literature is quite scarce, noting that it is essentially focused on a very restricted number of researchers. Some additional studies were also found in the literature focusing on the non-conventional machining of these alloys [29,30], as well as their tribological behavior in typical tests to evaluate the wear of pairs of materials [11,31,32,33,34,35,36].

The work now presented is intended to compare the behavior of non-coated tools and tools coated by PVD with TiAlN/DLC, a coating still little used in the cutting tool sector, with a view to analyzing possible advantages of using the coating and investigating which wear mechanisms are involved, both in non-coated tools and in tools coated with TiAlN/DLC. The aforementioned coating was selected because it is known that it allows obtaining properties such as lubrication and low friction on the surface (granted by the DLC surface layer) and resistance to high machining speeds and oxidation resistance (granted by the intermediate TiAlN layer), in a tungsten carbide-based tool, seeking to obtain an increase in productivity [37,38]. The main focus of the analysis was based on two main variables: feed rate and cutting length, because these parameters are usually reported as the most important in conditioning the tools’ wear behavior [2,3,21,26]. At the same time, a study was conducted on the machined surface quality, with a view to correlating the type of tool wear with the roughness of the machined surface. The novelty of this study is based on the scarce literature found about the materials used as workpiece material and the PVD coating used on the tools’ surface. This also was the main motivation to carry out this work.

2. Materials and Methods

2.1. Materials

2.1.1. Workpiece Material

The material of the workpiece consisted of AMPCOLOY^® 83, a copper–beryllium alloy. This material was provided in the shape of a parallelepiped, with dimensions of 155 × 115 × 155 (mm) and 22.5 kg, whereas at the beginning of the work, it was 155 × 115 × 120 (mm) and 17.4 kg. This workpiece was purchased from the company AMPCO Portugal (Porto, Portugal). The chemical composition of the AMPCOLOY^® 83 alloy is given in Table 1.

The copper–beryllium AMPCOLOY^® 83 alloy has good thermal and electrical conductivity, along with excellent mechanical properties. The material’s mechanical properties are presented in Table 2.

2.1.2. Substrate and Tool Configuration

The tools employed were end mills constructed from cemented carbide WC-Co substrate grade 6110, comprising cobalt as a binder (~6 wt%) and possessing an average grain size of 0.3 μm. INOVATOOLS, S.A. (Leiria, Portugal) supplied these tools. Table 3 presents a characterization of the tool configuration.

2.2. Methods

2.2.1. PVD Coating

The cutting tools were cleaned with acetone in an ultrasonic bath before the coating was deposited. This process was carried out in two stages: The first phase took about 15 min to complete, and then there was a change in acetone before the last cleaning step, which took 5 min to complete.

A 2.1 μm thick TiAlN\DLC coating was applied using the PVD HiPIMS method with CemeCom CC800/HiPIMS equipment (CemeCon, AG, Wuersele, Germany) with four high-purity (99.9%) target holders. For the deposition of the TiAlN initial layer, three targets with a chemical composition of Ti and Al were used. However, in the case of the deposition of the DLC coating, a carbon target was used. The selected parameters for the deposition are shown in Table 4. Based on prior successful experiments on similar substrates with various targets, these parameters were selected. Throughout the deposition process, great homogeneity of the deposited coatings was ensured by rotating the substrate holder at a speed of one revolution per minute.

2.2.2. Machining Experiments

Machining tests were performed using the CNC machining center HAAS VF-2 (HAAS Automation, Oxnard, CA, USA), a maximum speed of 10,000 rpm, with three axes to machine, and a maximum power (Pin) of 20 kW. The distance from the table to the spindle is 610 mm; the table is 914 mm long and 356 mm wide. A linear milling approach was selected due to the part being provided in a rectangular shape. Thus, milling occurred along the largest face of the stock, and the tool entry was carried out perpendicularly and externally to the edge of the stock with alternating concordant and discordant movements. This machining strategy ensures greater cutting distances with the smallest number of passes. The tests were carried out with Alusol SL 61 XBB (Castrol, Pangbourne, UK), a semi-synthetic metalworking fluid, containing 5% oil in water as cutting fluid.

To avoid wear-related issues, a linear method was used with respect to the milling parameters, and the radial depth of the cut was maintained constant at 3.6 mm (60% of the tool diameter), while the axial cutting depth was constant and 0.5 mm. These parameters were kept constant for all conditions tested. The cutting speed v_c adopted a constant value of 126 m/min, keeping the spindle rotation speed constant, which is a parameter to be modified in future studies. Based on preliminary testing and a comparison of coated and uncoated tools, the parameters f and L_cut were changed. These characteristics are thought to have the greatest influence on machining processes, as was previously mentioned [2,3,21,26]. Values of 18 m, 36 m, and 48 m were selected for L_cut in order to assess the wear’s advancement during the workpiece machining process. To compare and examine how feed rate affects the resulting wear and surface roughness, two different feed rates—750 mm/min and 1500 mm/min—were utilized for f. Table 5 displays all test parameters and conditions, and Figure 1 shows the workpiece along with the matching linear marks. For every set of parameters, five trials were conducted.

2.2.3. Surface Roughness Analysis

A Mahr Perthometer M1 profilometer provided with a Mahr probe (Mahr, Gottingen, Germany) was used to measure the roughness of the machined surface, operating in accordance with DIN EN ISO 10049:2005 [33]. The test was conducted according to DIN EN ISO 21920-3:2021 [38]. Table 6 presents the most relevant technical specifications of the Mahr Perthometer M1 profilometer.

The roughness measurement of the machined surface after each test performed was carried out with a cut-off value (λc) of 0.8 mm and a total measurement length of 5.6 mm, which corresponds to seven cut-offs. Additionally, the initial and final measurement sections of 0.8 mm were excluded because errors can result from the probe’s acceleration and deceleration during measurement. Furthermore, measurements were conducted both transversely and longitudinally to the machining direction, with at least five measurements taken in various regions to account for potential discrepancies between values obtained at the edges and at the core of the workpiece. These were used to calculate the arithmetic average roughness value (Ra), which led to a roughness assessment to evaluate the cutting tool’s stability and effectiveness. This evaluation can be connected to tool deterioration and the ideal milling parameters for achieving the best quality and surface integrity.

2.2.4. Wear Mechanisms Characterization

The cutting tools were cleaned with acetone using ultrasonic technology prior to examining the wear on them. Following ISO 8688-2:1986 [39], the damage incurred by the machining tools was evaluated through the application of Scanning Electron Microscopy (SEM) analysis. According to this standard, all wear occurrences should be examined for presence and the most substantial impact should be chosen as the life criterion. As a result, the VB3 was selected, and “Position 1” was used for the wear measurements. For this, an SU3800 Hitachi (Hitachi, Tokyo, Japan) scanning electron microscope was utilized. The analyses were conducted using Backscattered Electron (BSE), with magnification ranging from 100× to 2000× and a beam potential of 15 kV. Moreover, the existence of material adhering to the tool was verified and confirmed by an Energy-Dispersive X-ray Spectroscopy examination. All of the tools’ clearance faces (CFs), rake faces (RFs), and top views (TOP) were examined as part of the analysis. In addition, a reference was created for the tool’s four cutting edges, designating numbers 1 through 4 to help with identification.

3. Results and Discussion

The results were analyzed and discussed in three distinct categories, namely, the roughness of the machined surface, tool wear, and associated wear mechanisms. The results are evident in comparative studies using coated and uncoated tools and considering the same machining conditions.

3.1. An Analysis of the Machined Surface’s Roughness

In order to investigate the machined surface quality in both transverse and longitudinal directions, the surface roughness (SR) was measured after each testing condition. Considerable fluctuations were seen in the values acquired in various orientations, with an average discrepancy of almost 30% among the outcomes. The SR values obtained, which were arranged and categorized in accordance with Figure 2 as shown in Table 7, were used to compare all test circumstances. Six groups correspond to each of the test situations shown on the X-axis of the graph in Figure 2. It contrasts the total SR value and the SR values in the transverse and longitudinal directions for tools with and without coating. The Y-axis is used to display SR values. It is significant to note that the number following the “L” designates the L_cut, and the number following the “F” denotes the f used in the machining test, per the tool identification.

As can be seen in the graphs of Figure 3 and the corresponding values in Table 7, surface roughness values tend to increase with higher cutting lengths and feed rates. For the 1500 mm/min feed rate condition, the surface roughness values are the highest, both for coated and uncoated tools, and in general, the coating allows a better-quality surface finish. It is also evident that by augmenting the L_cut, the SR values have likewise risen, which was the anticipated outcome. Even with low L_cut values, significant tool wear can occur, increasing SR values and diminishing the quality of the machined surface [40]. The f influence is evident for the conditions tested at v_f = 750 mm/min and v_f = 1500 mm/min since, for a L_cut = 18 m, when the v_f was increased, the roughness also increased, reaching average differences of double. Identical wear results were obtained for L_cut = 36 and L_cut = 48 m, changing the v_f condition. Typically, lower values of v_f result in superior machined surface quality, indicated by reduced surface roughness [41]. This implies that an increase in v_f may compromise the quality of the surface being machined [42]. Therefore, under the conditions tested at v_f = 1500 mm/min, the maximum Ra value was obtained for the condition using L_cut = 48 m, condition L48F1500V126. The lowest Ra value was obtained for the condition v_f = 750 mm/min and a L_cut = 18 m, corresponding to the L18F750V126 condition.

Similarly to the conditions evaluated at 750 mm/min, under the conditions assessed at 1500 mm/min, an increase in L_cut resulted in a corresponding increase in roughness, hence highlighting the significance of this parameter. Furthermore, for a L_cut = 18 m, the same was observed as in the previous case: When the fz increased, the roughness of the machined surface also increased. Thus, increasing the f results in a decrease in the roughness of the machined surface. Therefore, it appears that this factor has a significant impact on the roughness of the machined surface [43].

Overall, it was observed that average Ra values typically rise with higher L_cut values, a trend that is registered for all conditions tested for both types of tools with and without coating. In certain circumstances, this increase is more evident, as in the L36F1500 and L48F1500 conditions, especially in the longitudinal direction. Conversely, this increase is minimal under some conditions, specifically in L18F15000 and L36F750 for the transverse direction, as indicated in Table 8.

It was possible to verify in Table 8 that the lowest roughness values were reported for coated tools, being on average lower by around 25%. However, analyzing only the longitudinal roughness, the difference increases to 36%. Hence, there is a tendency for a greater difference in roughness between coated and uncoated tools in readings taken longitudinally as the cutting length increases, with this difference being around 51% for the cutting length of 48 m under similar test conditions. Therefore, it can be said that the coating extends the tools’ lifespan.

For low values of f, L_cut is the most influential parameter. However, as the values of v_f increase, its effect on surface quality becomes less pronounced. In fact, it is always possible to verify an increase in the Ra value with an increase in L_cut, so it is possible to point out that this parameter is of particular importance. Conversely, f is the most significant parameter affecting surface quality, and this effect is more evident. It was verified that the increase in f from 750 mm/min to 1500 mm/min results in Ra results twice as high.

The coating has been shown as the most critical parameter, together with f and L_cut. Globally, it is visible that the use of coated tools leads to a reduction in Ra. However, this trend is not 100% consistent. However, when it comes to the most extreme setups, the quality of the surface is significantly impacted by the coating.

As a result, the machined surface quality was adequate, exhibiting favorable surface roughness results. Considering the above, it was possible to verify in all tests that the tools that were coated resulted in an improved surface finish on the machined part when compared to the uncoated ones.

3.2. Wear Analysis

As outlined in Section 2.2.4, the assessment of tool wear was conducted in accordance with ISO 8688-2:1986 [39] for the top view of the tools (VB3). In order to compare all test conditions, the values obtained for VB3 were organized and grouped according to Figure 3; the sum is shown in Table 9. Figure 4 is organized by test conditions on the X-axis of the graph, with six groups corresponding to identical machining conditions on coated and uncoated tools, carrying out tests with variations in L_cut and f in three different conditions. It is important to mention that, according to the identification of the tools, the number after the “F” indicates the f, and the number after the “L” indicates the L_cut used in the machining test. These values will be presented in the form of a graph with the average wear values in Figure 4 for the feed rates of 750 mm/min and 1500 mm/min.

High values of deviation were observed, compared to the average wear measured, since on several occasions, and particularly in uncoated tools, fractures of only one or two cutting edges occurred. As observed in Table 9, the flank wear corresponding to uncoated tools is lower for the condition of a lower f of 750 mm/min, with flank wear increasing as the feed rate increases. An increase in flank wear was also recorded as the cutting length increased, except in cases of tool breakage, which had an extremely high influence on wear. For coated tools, wear increased with an increasing feed rate, reaching a maximum average VB3 of close to 0.8 mm, which corresponds to a f of 1500 mm/min. Wear also increased as the cutting length increased. However, for the f of 750 mm/min, its increase was practically imperceptible, as minimal differences were reported between wear values. When comparing results between coated and uncoated tools, it was possible to identify that the cutting length and feed rate are factors that greatly increase the average wear value, particularly when using uncoated tools, which present a value twice as high overall average wear compared to the use of coated tools. The minimum values of flank wear on coated tools were obtained for lower cutting lengths and feed rate values. Furthermore, as recorded in the analysis of visual comparison data, coated tools suffer less wear than uncoated ones for all feed rates and cutting lengths. Analyzing Figure 3, there is greater wear on tools with lower cutting lengths and a similar feed rate. This situation is due to the difference in wear measured due to the fracture of the cutting edges. Generally, coated tools with lower cutting speeds have low average flank wear when compared to other conditions. This means that these tools have better wear behavior for longer cutting lengths, suffer less flank wear, and allow greater machining distances. It is also possible to notice a clear increase in the average VB value with increasing cutting length, particularly for uncoated tools. This increase is experienced by all tools. However, it is not as intense for tools with lower cutting speeds.

For conditions tested at a f = 750 mm/min, the influence of the L_cut is evidently clear when the L_cut increases from 18 m to 48 m, both on coated and uncoated tools. Concerning the impact of the variation in f on the flank wear of the tools, for a L_cut of 18 m, the lowest value obtained was for condition L18F750 with coated tools. Wear increased when f changed from 750 mm/min to 1500 mm/min and decreased when using a coated tool. The same trend was observed for the cases tested at L_cut = 36 m and 48 m: increased wear was observed in both. At v_f = 1500 mm/min and L_cut = 48 m, the maximum VB was observed both in coated and uncoated tools.

Under all settings, VB3 increased as L_cut increased. However, increased wear is more relevant for uncoated tools. This is due to the coating properties, which cause additional protection for the tool due to the typical TiAlN and DLC properties. Overall, it was noted that the coating had a noticeable impact on the VB rise. Furthermore, the multilayered coating of TiAlN and DLC presents mechanical properties such as resistance to impact and the occurrence of cracks, as well as lubrication and reduction in friction. Thus, when the f increases, the consequent wear likewise induces the coating to be able to mitigate this effect. This rise in VB corresponds with the roughness achieved and the quality of the machined part surface. Nevertheless, a higher f generally leads to improved surface quality and a more uniform cutting performance of the cutting tools [44].

3.3. Wear Mechanisms Analysis

3.3.1. f of 750 mm/min

In relation to the VB3 type found in tools tested at 750 mm/min, Figure 4 shows the top view of the uncoated and coated tools tested under conditions L18F750V126, L36F750V126, and L48F750V126, allowing for the observation of the impact of L_cut and coating on wear outcome.

Regarding the wear mechanism, it can be stated that abrasion and adhesive wear were the primary types found under 750 mm/min, on both the substrate (uncoated and coated tools) and the coating (coated tools). Additionally, under some circumstances, cracking and fracture of the substrate transpired on uncoated tools, whereas delamination and cracking of the coating occurred on coated tools. Adhesion and abrasion are frequent wear mechanisms that affect the wear that cutting tools experience throughout the milling process [45]. Figure 5 compares the condition of coated and uncoated tools and shows the abrasive wear that occurred on the substrate of the cutting tool under the L18F750V126, L36F750V126, and L48F750V126 conditions, where, for 48 m, the wear is more prominent. Abrasive wear was observed in all tests and was particularly pronounced and severe for L_cut = 48 m.

Regarding the existence of attached content, it was seen in large quantities and under all circumstances, which is due to the traditional Cu softness. This outcome is not surprising, as AMPCOLOY^® 83 frequently sticks to tools for cutting. Figure 5 shows the adhered material on the clearance faces of the L36F750V126 and L48F750V126 conditions. Additionally, the coating displayed wear mechanisms like fractures, delamination, adhesion of the workpiece material, and abrasion. The tool substrate showed fewer occurrences of abrasive and adhesive wear. Adhesion of the material results in increased abrasion and may cause coating delamination [40], due to Be hard particles ripped out of the workpiece. Figure 6 illustrates the wear mechanisms identified in the coating. In Figure 6a, abrasive wear and adhered material can be observed in the T0L48F750V126 condition, and in Figure 6b, delamination and cracking can be seen in a cutting tool tested in the T1L48F750V126 condition. Moreover, it can be argued that the wear mechanisms observed in the coating of the cutting tool were more severe during the tests at L_cut = 48 m.

Therefore, it seems that the increase in L_cut caused the development of increased wear mechanisms, including wear from friction and sticking of the workpiece material on the tool surface occurs on both coated and uncoated tools. As the test advances, the adhesion of the material is enhanced because it gathers in the grooves on the tool’s surface, thanks to a grinding effect [42]. Thus, with a longer L_cut, there will be a greater buildup of material leading to increased abrasive wear. This could result in coating delamination and substrate wear mechanisms and intensity, different from the coating. Under these conditions, coating wear progressively occurred in almost all situations as the L_cut increased. However, substrate delamination is reduced by the existence of a self-lubricant DLC coating (comparing Figure 6c and Figure 6d, with identical cutting conditions), which also indicates that the coating acts as a protective layer for the tool. In addition, the lowest wear among all conditions was verified on uncoated tools with the highest cutting compliance, as shown in Figure 6c.

3.3.2. f of 1500 mm/min

Figure 7 shows the top view of tools used under L18F1500V126, L36F1500V126, and L48F1500V126 conditions, where it is possible to observe the effect of L_cut and the coating on the machining in these conditions.

As can be observed in the pictures previously shown, the impact of the L_cut significantly increases the resulting wear. In the first phase, the coating preserves and reduces tool wear. However, after its detachment or abrasion, the substrate tends to be less effective in sustaining the wear. This is evident in the conducted measurements and the SEM images acquired. Regarding the impact of f, tools tested with higher f have wider, more distinct, and deeper wear marks. This is related to the process of creating chips and has the ability to alter the shape of the tools [46].

Abrasion and adhesion of workpiece material were the main wear mechanisms observed on both the tool substrate and coating, with the adhesion being more pronounced compared to tests conducted at 1500 mm/min on uncoated tools.

It has been noted that AMPCOLOY^® 83 attaches to cutting tools and wears abrasively. As seen in Figure 8, the abrasive wear was more noticeable on the tools’ clearance face, and this kind of wear is typical when machining this alloy.

In the coating, it is possible to observe delamination and substrate chipping as wear mechanisms, along with material adhesion and abrasion. Figure 9 depicts adherent material, delamination on the coating, and substrate chipping. The process performance is adversely affected by this chipping [47] because of the altered geometry of the cutting tool [48], which induces a different surface topography. The absence of cracking in the tool substrate can also be reported.

Figure 10 depicts the four zones in which the analysis was conducted as well as the material’s adherence to the tool substrate under the T1L18F1500V126 condition. The rake face, flank, and tool edges all showed signs of wear. In this instance, EDS analysis was carried out based on the chemical composition that the study revealed to establish the existence of AMPCOLOY^® 83. The results of the EDS tests for the four relevant zones are displayed in Figure 11.

In the spectrum represented in Figure 11a, elements related to the substrate were found, with tungsten being clearly detected, as well as cobalt and carbon elements, though in smaller quantities. In the spectrum represented in Figure 11b, it is possible to identify the Z1 layer elements, such as Ti, Al, and N, corresponding to the TiAlN layer. The element detected in the highest concentration was aluminum. Considering the type of deposition carried out, with variations in elements and gradient transitions that cause variations in the quantity of elements, another position within the same zone could present a different proportion between elements. In Figure 11c, it is perfectly noticeable that carbon is the element in the greatest quantity in the upper layer, as would be expected, given that DLC coating is present in this area. As can be seen in Figure 11d, Cu was detected, referring to the adhered machined material, AMPCOLOY^® 83. Because of the chemistry of the parts in the image that are highlighted, the results are consistent.

4. Conclusions

The current work describes how different milling parameters affect the quality of the machined surface and the wear of the tool, using coated and uncoated tools, with the main target of studying the influence of feed rate and cutting length on the wear mechanisms and machined surface quality. Based on the results obtained, the following conclusions can be drawn:

• The coating under study exhibited a reduction in adhesion and in the wear phenomena, despite showing some delamination phenomenon, mainly on the cutting edges.

• The coating proves to be more effective for shorter L_cut, and the reduction in f allows roughness to be improved, consequently increasing working time.

• The tool wear is about half on coated tools compared to equal conditions using uncoated tools.

• The process is affected by the machining parameters, with the greatest impact coming from the L_cut.

• The T1L18F750V126 condition granted the smallest roughness values for the machined surface.

• The f and L_cut had an influence on roughness.

• The highest VB was seen with the T0L48F1500V126 setting, while the lowest was with the T1L18F750V126 setting, both impacted by the L_cut and the presence of the coating.

• For higher f and L_cut values, the wear developed was more extreme.

• The predominant wear mechanisms were abrasive wear and adhesive wear on the coating and the tool substrate. Delamination and chipping were also observed in the coated tools.

• Reduced breakage of cutting edges for coated tools.

• The results allowed us to observe that, for machining AMPCOLOY^® 83, tools coated with TiAlN/DLC are more effective.

Hence, the findings indicate a necessity for additional improvement in the process, particularly concerning the excessive wear on the coating. Coating adhesion needs enhancement as coating delamination was seen in all situations. This problem can be solved by adjusting in a better way the PVD deposition parameters. However, coated tools demonstrate less intense wear behavior and produce better surface quality, when compared to uncoated tools, under identical test conditions.

Generally, significant improvements in the lifespan provided by the coating of the cutting tool were detected when machining the AMPCOLOY^® 83 alloy. Although the coating is subject to delamination, it provides greater resistance and an increased tool lifespan. Uncoated tools showed greater wear and resulted in a worse surface finish. This indicates that this coating is more suitable for machining operations of copper–beryllium alloys, for the machining strategy used, although it can be improved further. The results unequivocally demonstrate the necessity for a fresh investigation centered on coating deposition parameters and the optimization of machining parameters.

Due to the scarce literature found in studies related to the tool wear behavior in milling AMPCOLOY^® 83, as well as tribological investigations on the wear behavior of multilayered TiAlN/DLC coatings in tools used in machining this alloy, this work intends to make a little contribution to the overall knowledge around these coatings and machining behavior.

Author Contributions

Conceptualization, F.J.G.S., F.R.S.F. and R.C.B.C.; methodology, F.J.G.S. and R.C.B.C.; validation, F.F., N.P.V.S., V.F.C.S., R.P.M. and R.C.M.S.-C.; formal analysis, F.F., N.P.V.S., V.F.C.S., R.P.M. and R.C.M.S.-C.; investigation, F.R.S.F. and N.P.V.S.; resources, F.J.G.S. and R.C.M.S.-C.; data curation, F.F., N.P.V.S., V.F.C.S., R.P.M. and R.C.M.S.-C.; writing—original draft preparation, F.R.S.F.; writing—review and editing, F.J.G.S., F.F., V.F.C.S. and R.C.M.S.-C.; visualization, F.F., N.P.V.S., V.F.C.S., R.P.M. and R.C.M.S.-C.; project administration, F.J.G.S. All authors have read and agreed to the published version of the manuscript.

Data Availability Statement

The original contributions presented in the study contain all data available.

Conflicts of Interest

The authors declare no conflicts of interest.

Footnotes

Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Figures and Tables

Figure 1. Workpiece material and its linear marks.

Figure 2. Comparison of SR values acquired under each evaluated situation.

Figure 3. Comparison of VB3 values obtained for all conditions tested.

Figure 4. Top view of the tools tested at f of 750 mm/min: (a) N1T0L18F750V126, (b) N7T1L18F750V126, (c) N2T0L36F750V126, (d) N8T1L36F750V126, (e) N3T0L48F750V126, and (f) N9T1L48F750V126.

Figure 5. Clearance face of the tools tested at a vf of 750 mm/min and 270× magnification: (a) N1T0L18F750V126, (b) N7T1L18F750V126, (c) N2T0L36F750V126, (d) N8T1L36F750V126, (e) N3T0L48F750V126, and (f) N9T1L48F750V126.

Figure 6. Rake face of the tools tested at vf of 750 mm/min: (a) N1T0L18F750V126, (b) N7T1L18F750V126, (c) N3T0L48F750V126, and (d) N9T1L48F750V126.

Figure 7. Top view of the tools tested at vf of 1500 mm/min: (a) N4T0L18F1500V126, (b) N10T1L18F1500V126, (c) N5T0L36F1500V126, (d) N11T1L36F1500V126, (e) N6T0L48F1500V126, and (f) N12T1L48F1500V126.

Figure 8. Clearance face of the tools tested at f of 1500 mm/min: (a) N4T0L18F1500V126, (b) N10T1L18F1500V126, (c) N5T0L36F1500V126, (d) N11T1L36F1500V126, (e) N6T0L48F1500V126, and (f) N12T1L48F1500V126.

Figure 9. Adhered material, delamination, and chipping in RF3 of one of the tools used under N11T1L36F1500V126 condition.

Figure 10. Tools under the N10T1L18F1500V126 condition reveal material adhesion, as can be observed in the spectra generated during the EDS analysis.

Figure 11. EDS spectra analysis of the four areas pointed out in one of the tools used under N10T1L18F1500V126 condition: (a) Z1—tool substrate, (b) Z2—coating TiAlN and adhered machined material AMPCOLOY® 83, (c) Z3—coating DLC, and (d) Z4—adhered machined material AMPCOLOY® 83.

Figure 11. EDS spectra analysis of the four areas pointed out in one of the tools used under N10T1L18F1500V126 condition: (a) Z1—tool substrate, (b) Z2—coating TiAlN and adhered machined material AMPCOLOY® 83, (c) Z3—coating DLC, and (d) Z4—adhered machined material AMPCOLOY® 83.

Table 1

Chemical composition of the copper–beryllium alloy AMPCOLOY^® 83 (wt%).

	Copper(Cu)	Beryllium(Be)	Cobalt + Nickel (Co) + (Ni)	Others
Percentage (wt%)	97.1	1.9	0.5	Maximum 0.5

Table 2

Mechanical properties of the AMPCOLOY^® 83 alloy.

Material Property	Value
Yield strength (MPa)	1000
Tensile strength (MPa)	1250
Young’s modulus (GPa)	131
Elongation (%)	4
Rockwell hardness (HRC)	40
Brinell hardness (HBW 10/3000)	380
Density (g/cm3)	8.26
Expansion coefficient (10−6/K)	17.5
Electrical conductivity (m/Ω∙mm2)	12.8
Thermal conductivity (W/m·K)	106
Specific heat (J/g·K)	0.38

Table 3

The WC-Co end mill arrangement utilized in the experiment.

Tool Geometry	Value
Cutting Ø (mm)	6
Overall length (mm)	57
Maximum depth of cut (mm)	13
Chamfer (°, mm)	45, 0.20
Rake angle (°)	12
Clearance angle (°)	10
Helix angle (°)	35
Number of flutes (-)	4

Table 4

Parameters of the deposition of TiAlN\DLC coating.

Deposition Parameters	TiAlN	DLC
Deposition time (min)	120
Gases	Ar+ + N2 (300 mln + 100 mln)
Target amount/composition	3 × TiAl	1 × C—Graphite
Pressure (mPa)	600
Average power (kW)	6
Bias voltage (V)	−60
Holder rotational speed (rpm)	1

Table 5

Conditions and parameters used in milling tests.

Reference	Coated Tool	vc(m/min)	f(mm/min)	ap(mm)	ae(mm)	Lcut(m)
N1T0L18F750V126	No	126	750	0.5	3.6	18
N2T0L36F750V126	No	126	750	0.5	3.6	36
N3T0L48F750V126	No	126	750	0.5	3.6	48
N4T0L18F1500V126	No	126	1500	0.5	3.6	18
N5T0L36F1500V126	No	126	1500	0.5	3.6	36
N6T0L48F1500V126	No	126	1500	0.5	3.6	48
N7T1L18F750V126	Yes	126	750	0.5	3.6	18
N8T1L36F750V126	Yes	126	750	0.5	3.6	36
N9T1L48F750V126	Yes	126	750	0.5	3.6	48
N10T1L18F1500V126	Yes	126	1500	0.5	3.6	18
N11T1L36F1500V126	Yes	126	1500	0.5	3.6	36
N12T1L48F1500V126	Yes	126	1500	0.5	3.6	48

Table 6

Technical information about the Mahr Perthometer M1 profilometer.

Parameters	Value
Measurement speed (mm/s)	0.5
Measuring range (μm)	100/150
Profile resolution (nm)	12
Cut-offs (mm)	0.25/0.8/2.5
Filter	Gaussian
Travel length (mm)	1.75/5.6/17.5
Sample length (mm)	1–5
DIN/ISO	Ra Rz Rmáx RPc

Table 7

Ra values for all conditions tested.

Reference	Average Ra Transverse Value (μm)	Average Ra Longitudinal Value (μm)	Ra GlobalValue (μm)
N1T0L18F750V126	0.4246 ± 0.0322	0.2970 ± 0.0408	0.3608
N2T0L36F750V126	0.5290 ± 0.0395	0.3066 ± 0.0424	0.4178
N3T0L48F750V126	0.6358 ± 0.0459	0.3334 ± 0.0699	0.4846
N4T0L18F1500V126	0.7992 ± 0.0593	0.8212 ± 0.0512	0.8102
N5T0L36F1500V126	0.9508 ± 0.0372	1.1426 ± 0.0749	1.0467
N6T0L48F1500V126	1.1522 ± 0.0486	1.2626 ± 0.1649	1.2074
N7T1L18F750V126	0.3416 ± 0.0552	0.2040 ± 0.0384	0.2728
N8T1L36F750V126	0.4750 ± 0.0541	0.2232 ± 0.0586	0.3491
N9T1L48F750V126	0.5054 ± 0.0229	0.2690 ± 0.0380	0.3872
N10T1L18F1500V126	0.7700 ± 0.0595	0.5038 ± 0.0820	0.6369
N11T1L36F1500V126	0.8624 ± 0.0375	0.5846 ± 0.0552	0.7235
N12T1L48F1500V126	0.9426 ± 0.0494	0.6142 ± 0.0548	0.7784

Table 8

Percentage difference of Ra values with equal machining parameters, between coated and uncoated tools.

Uncoated vs. Coated	RaTransverse (%)	RaLongitudinal (%)	RaGlobal (%)
N1T0L18F750V126 vs. N7T1L18F750V126	20	31	25
N2T0L36F750V126 vs. N8T1L36F750V126	10	27	19
N3T0L48F750V126 vs. N9T1L48F750V126	21	19	20
N4T0L18F1500V126 vs. N10T1L18F1500V126	4	39	21
N5T0L36F1500V126 vs. N11T1L36F1500V126	9	49	29
N6T0L48F1500V126 vs. N12T1L48F1500V126	18	51	35
Global Difference	14	36	25

Table 9

Average values of VB3 for all conditions tested.

Reference	Average VB3 Value (μm)
N1T0L18F750V126	0.2275 ± 0.1404
N2T0L36F750V126	0.3250 ± 0.1436
N3T0L48F750V126	0.8650 ± 0.3629
N4T0L18F1500V126	0.6675 ± 0.4295
N5T0L36F1500V126	1.4225 ± 0.2772
N6T0L48F1500V126	1.5225 ± 0.2605
N7T1L18F750V126	0.0950 ± 0.0333
N8T1L36F750V126	0.2575 ± 0.1992
N9T1L48F750V126	0.2625 ± 0.2296
N10T1L18F1500V126	0.1725 ± 0.0764
N11T1L36F1500V126	0.3800 ± 0.2661
N12T1L48F1500V126	0.7425 ± 0.4214

References

1. Zhang, L.; Ma, C.; Liu, J. Enhancing four-axis machining center accuracy through interactive fusion of spatiotemporal graph convolutional networks and an error-controlled digital twin system. J. Manuf. Process.; 2024; 112, pp. 14-31. [DOI: https://dx.doi.org/10.1016/j.jmapro.2024.01.024]

2. Sousa, V.F.C.; Silva, F.J.G. Recent Advances on Coated Milling Tool Technology—A Comprehensive Review. Coatings; 2020; 10, 235. [DOI: https://dx.doi.org/10.3390/coatings10030235]

3. Sousa, V.F.C.; Silva, F.J.G. Recent Advances in Turning Processes Using Coated Tools—A Comprehensive Review. Metals; 2020; 10, 170. [DOI: https://dx.doi.org/10.3390/met10020170]

4. Portman, V.T.; Kushnir, E. Drives’ stiffness of 5-axis machine designs: Evaluation and comparison by Schur complement eigenvalues. Procedia CIRP; 2023; 118, pp. 169-174. [DOI: https://dx.doi.org/10.1016/j.procir.2023.06.030]

5. Russo, M.; Zhang, D.; Liu, X.-J.; Xie, Z. A review of parallel kinematic machine tools: Design, modeling, and applications. Int. J. Mach. Tools Manuf.; 2024; 196, 104118. [DOI: https://dx.doi.org/10.1016/j.ijmachtools.2024.104118]

6. Asgari, A.; Sedighi, M. Investigation on the optimal machining of Mg-based composites considering surface roughness, tool life, cutting forces, and productivity. Proc. Inst. Mech. Eng. Part C J. Mech. Eng. Sci.; 2022; 237, pp. 1139-1152. [DOI: https://dx.doi.org/10.1177/09544062221128693]

7. Xu, Z.; Zhu, T.; Luo, F.L.; Zhang, B.; Poon, H.; Yip, W.S.; To, S. A review: Insight into smart and sustainable ultra-precision machining augmented by intelligent IoT. J. Manuf. Syst.; 2024; 74, pp. 233-251. [DOI: https://dx.doi.org/10.1016/j.jmsy.2024.03.008]

8. Duc, T.M.; Tuan, N.M.; Long, T.T.; Ngoc, T.B. Machining feasibility and Sustainability study associated with air pressure, air flow rate, and nanoparticle concentration in Nanofluid minimum quantity lubrication-assisted hard milling process of 60Si2Mn steel. J. Mech. Eng. Sci.; 2022; 236, pp. 11256-11269. [DOI: https://dx.doi.org/10.1177/09544062221111253]

9. Çakir, F.H.; Yilmaz, A.; Sert, Z. Evaluation of the performance of DLC Coatings (ta-C) of WC-Co tools while machining Al7075 alloy. Proc. Inst. Mech. Eng. Part C J. Mech. Eng. Sci.; 2024; 238, pp. 8151-8163. [DOI: https://dx.doi.org/10.1177/09544062241237425]

10. Roy, S.; Das, A.; Kumar, R.; Das, S.R.; Rafighi, M.; Sharma, P. Exploring the viability of alternative cooling-lubrication strategies in machining processes: A comprehensive review on the performance and sustainability assessment. Proc. Inst. Mech. Eng. Part B J. Eng. Manuf.; 2024; 09544054241229472. [DOI: https://dx.doi.org/10.1177/09544054241229472]

11. Rouxel, B.; Mischler, S.; Logé, R.; Munoz, A.I. Wear behaviour of novel copper alloy as an alternative to copper-beryllium. Wear; 2023; 524–525, 204817. [DOI: https://dx.doi.org/10.1016/j.wear.2023.204817]

12. ASM International. Surface Engineering; ASM International: Novelty, OH, USA, 1994.

13. Jakubowski, M.; PałczyŃski, C. Chapter 30—Beryllium. Handbook on the Toxicology of Metals; 4th ed. Nordberg, G.F.; Fowler, B.A.; Nordberg, M. Academic Press: San Diego, CA, USA, 2015; pp. 635-653.

14. Wang, Z.; Kovvuri, V.; Araujo, A.; Bacci, M.; Hung, W.N.P.; Bukkapatnam, S.T.S. Built-up-edge effects on surface deterioration in micromilling processes. J. Manuf. Process.; 2016; 24, pp. 321-327. [DOI: https://dx.doi.org/10.1016/j.jmapro.2016.03.016]

15. Dong, S.; Wang, Z.; Wang, Y. Research on micro-EDM with an auxiliary electrode to suppress stray-current corrosion on C17200 beryllium copper alloy in deionized water. Int. J. Adv. Manuf. Technol.; 2017; 93, pp. 857-867. [DOI: https://dx.doi.org/10.1007/s00170-017-0478-8]

16. Lipa, M.; Durocher, A.; Tivey, R.; Huber, T.; Schedler, B.; Weigert, J. The use of copper alloy CuCrZr as a structural material for actively cooled plasma facing and in vessel components. Fusion Eng. Des.; 2005; 75–79, pp. 469-473. [DOI: https://dx.doi.org/10.1016/j.fusengdes.2005.06.056]

17. Khodabakhshi, A.; Abouei, V.; Mortazavi, N.; Razavi, S.H.; Hooshyar, H.; Esmaily, M. Effects of cold working and heat treatment on microstructure and wear behaviour of Cu–Be alloy C17200. Tribol.-Mater. Surfaces Interfaces; 2015; 9, pp. 118-127. [DOI: https://dx.doi.org/10.1080/17515831.2015.1107257]

18. Çakıroğlu, R.; Günay, M. Analysis of surface roughness and energy consumption in turning of C17500 copper alloy under different machining environments and modellings with response surface method. Proc. Inst. Mech. Eng. Part E J. Process. Mech. Eng.; 2023; 237, pp. 207-219. [DOI: https://dx.doi.org/10.1177/09544089221101368]

19. ASTM B 194-15 Standard Specification for Copper-Beryllium Alloy Plate, Sheet, Strip, and Rolled Bar; ASTM International: Conshohocken, PA, USA, 2015.

20. Sharma, A.; Datta, D.; Balasubramaniam, R. An investigation of tool and hard particle interaction in nanoscale cutting of copper beryllium. Comput. Mater. Sci.; 2018; 145, pp. 208-223. [DOI: https://dx.doi.org/10.1016/j.commatsci.2018.01.011]

21. Sharma, A.; Joshi, S.S.; Datta, D.; Balasubramaniam, R. Modeling and analysis of tool wear mechanisms in diamond turning of copper beryllium alloy. J. Manuf. Process.; 2020; 56 Pt A, pp. 439-450. [DOI: https://dx.doi.org/10.1016/j.jmapro.2020.04.053]

22. Sharma, A.; Datta, D.; Balasubramaniam, R. A molecular dynamics simulation of wear mechanism of diamond tool in nanoscale cutting of copper beryllium. Int. J. Adv. Manuf. Technol.; 2019; 102, pp. 731-745. [DOI: https://dx.doi.org/10.1007/s00170-018-03246-0]

23. Sharma, A.; Joshi, S.S.; Datta, D.; Balasubramaniam, R. Investigation of Tool and Workpiece Interaction on Surface Quality While Diamond Turning of Copper Beryllium Alloy. J. Manuf. Sci. Eng.; 2020; 142, 021011. [DOI: https://dx.doi.org/10.1115/1.4045721]

24. Sharma, A.; Kumar, A. Atomic scale insights into material removal mechanisms in nanoscale machining of copper beryllium. J. Micromanuf.; 2023; 25165984231203091. [DOI: https://dx.doi.org/10.1177/25165984231203091]

25. Zuo, J.; Lin, Y.; Zhong, P.; Liu, Y. Investigation on adhesive wear process of tool coating surface under high-adhesive rate environment in cutting Beryllium-copper C17200 alloy. Mater. Lett.; 2020; 279, 128488. [DOI: https://dx.doi.org/10.1016/j.matlet.2020.128488]

26. Sousa, V.F.C.; Castanheira, J.; Silva, F.J.G.; Fecheira, J.S.; Pinto, G.; Baptista, A. Wear Behavior of Uncoated and Coated Tools in Milling Operations of AMPCO (Cu-Be) Alloy. Appl. Sci.; 2021; 11, 7762. [DOI: https://dx.doi.org/10.3390/app11167762]

27. Nogueira, F.R.; Pedroso, A.F.V.; Silva, F.J.G.; Campilho, R.D.S.G.; Sales-Contini, R.C.M.; Sebbe, N.P.V.; Casais, R.C.B. A Comparative Study on the Wear Mechanisms of Uncoated and TiAlTaN-Coated Tools Used in Machining AMPCO^® Alloy. Coatings; 2024; 14, 4. [DOI: https://dx.doi.org/10.3390/coatings14010004]

28. Sudhakar, K.V.; Cisneros, J.C.; Cervantes, H.; Pineda, C.G. Machining Characteristics and Fracture Morphologies in a Copper-Beryllium (Cu-2Be) Alloy. J. Mater. Eng. Perform.; 2006; 15, pp. 117-121. [DOI: https://dx.doi.org/10.1361/105994906X83510]

29. Rebelo, J.C.; Dias, A.M.; Mesquita, R.; Vassalo, P.; Santos, M. An experimental study on electro-discharge machining and polishing of high strength copper–beryllium alloys. J. Mater. Process. Technol.; 2000; 103, pp. 389-397. [DOI: https://dx.doi.org/10.1016/S0924-0136(99)00492-6]

30. Yildiz, Y.; Sundaram, M.M.; Rajurkar, K.P. Statistical analysis and optimization study on the machinability of beryllium–copper alloy in electro discharge machining. Proc. Inst. Mech. Eng. Part B J. Eng. Manuf.; 2012; 226, pp. 1847-1861. [DOI: https://dx.doi.org/10.1177/0954405412457610]

31. Mouda, P.A.; Azeez, A.; Hydershah, S.J. Sliding Wear Behavior of Cryogenic Treated Copper Beryllium Alloy. Appl. Mech. Mater.; 2016; 852, pp. 391-396. [DOI: https://dx.doi.org/10.4028/www.scientific.net/AMM.852.391]

32. Xu, Z.; Huang, Z.; Wang, Y.; Lin, C.; Xu, X. Friction and Wear Behavior of C17200 Copper-Beryllium Alloy in Dry and Wet Environments. J. Mater. Eng. Perform.; 2021; 30, pp. 7542-7551. [DOI: https://dx.doi.org/10.1007/s11665-021-05969-w]

33. Zhou, Q.; Jiao, Z.; Huang, Z.; Shi, Y.; Li, Y.; Yin, C.; Wang, H.; Pinto, H.C.; Greiner, C.; Liu, W. Wear-resistant CrCoNi nanocrystalline film via friction-driven surface segregation. Acta Mater.; 2024; 279, 120299. [DOI: https://dx.doi.org/10.1016/j.actamat.2024.120299]

34. Zhang, Y.; Hou, W.; Yu, J.; Chen, C.; Zhou, L. The Role of Carbon in Wear Resistance of CoCrFeNiTi0.5 High-Entropy Alloy Layer. J. Mater. Eng. Perform.; 2024; pp. 1-13. [DOI: https://dx.doi.org/10.1007/s11665-023-09101-y]

35. Huang, X.; Etsion, I.; Shao, T. Effects of elastic modulus mismatch between coating and substrate on the friction and wear properties of TiN and TiAlN coating systems. Wear; 2015; 338–339, pp. 54-61. [DOI: https://dx.doi.org/10.1016/j.wear.2015.05.016]

36. Kim, J.-E.; Choi, J.I.J.; Kim, J.; Mun, B.S.; Kim, K.-J.; Park, J.Y. In-Situ Nanotribological Properties of Ultrananocrystalline Diamond Films Investigated with Ambient Pressure Atomic Force Microscopy. J. Phys. Chem. C; 2021; 125, pp. 6909-6915. [DOI: https://dx.doi.org/10.1021/acs.jpcc.1c00454]

37. EN 10049:2005 Measurement of Roughness Average Ra and Peak Count RPc on Metallic Flat Products; European Standard of the European Committee for Standardization: Brussels, Belgium, 2005.

38. ISO 21920-3:2021 Geometrical Product Specifications (GPS)—Surface Texture: Profile—Part 3: Specification Operators; International Organization for Standardization: Geneva, Switzerland, 2021.

39. ISO 8688-2:1986 Tool Life Testing in Milling—Part 2: End Milling; International Organization for Standardization: Geneva, Switzerland, 1986.

40. Sebbe, N.P.V.; Fernandes, F.; Silva, F.J.G.; Sousa, V.F.C.; Sales-Contini, R.C.M.; Campilho, R.D.S.G.; Pedroso, A.F.V. Wear Behavior Analysis of TiN/TiAlN Coated Tools in Milling of Inconel 718. Flexible Automation and Intelligent Manufacturing: Establishing Bridges for More Sustainable Manufacturing Systems; Springer Nature: Cham, Switzerland, 2024; pp. 784-795. [DOI: https://dx.doi.org/10.1007/978-3-031-38241-3_87]

41. Kumar, S.; Saravanan, I.; Patnaik, L. Optimization of surface roughness and material removal rate in milling of AISI 1005 carbon steel using Taguchi approach. Mater. Today Proc.; 2020; 22, pp. 654-658. [DOI: https://dx.doi.org/10.1016/j.matpr.2019.09.039]

42. Sousa, V.F.C.; Fernandes, F.; Silva, F.J.G.; Costa, R.D.F.S.; Sebbe, N.; Sales-Contini, R.C.M. Wear Behavior Phenomena of TiN/TiAlN HiPIMS PVD-Coated Tools on Milling Inconel 718. Metals; 2023; 13, 684. [DOI: https://dx.doi.org/10.3390/met13040684]

43. Airao, J.; Chaudhary, B.; Bajpai, V.; Khanna, N. An Experimental Study of Surface Roughness Variation in End Milling of Super Duplex 2507 Stainless Steel. Mater. Today Proc.; 2018; 5, Pt 1, pp. 3682-3689. [DOI: https://dx.doi.org/10.1016/j.matpr.2017.11.619]

44. Korkut, I.; Donertas, M. The influence of feed rate and cutting speed on the cutting forces, surface roughness and tool–chip contact length during face milling. Mater. Des.; 2007; 28, pp. 308-312. [DOI: https://dx.doi.org/10.1016/j.matdes.2005.06.002]

45. Akhtar, W.; Sun, J.; Sun, P.; Chen, W.; Saleem, Z. Tool wear mechanisms in the machining of Nickel based super-alloys: A review. Front. Mech. Eng.; 2014; 9, pp. 106-119. [DOI: https://dx.doi.org/10.1007/s11465-014-0301-2]

46. Sousa, V.F.C.; Da Silva, F.J.G.; Pinto, G.F.; Baptista, A.; Alexandre, R. Characteristics and Wear Mechanisms of TiAlN-Based Coatings for Machining Applications: A Comprehensive Review. Metals; 2021; 11, 260. [DOI: https://dx.doi.org/10.3390/met11020260]

47. Lu, Y.; Wu, S.; Gan, Y.; Huang, T.; Yang, C.; Junjie, L.; Lin, J. Study on the microstructure, mechanical property and residual stress of SLM Inconel-718 alloy manufactured by differing island scanning strategy. Opt. Laser Technol.; 2015; 75, pp. 197-206. [DOI: https://dx.doi.org/10.1016/j.optlastec.2015.07.009]

48. Virdi, R.L.; Chatha, S.S.; Singh, H. Performance Evaluation of Inconel 718 under vegetable oils based nanofluids using Minimum Quantity Lubrication Grinding. Mater. Today Proc.; 2020; 33, pp. 1538-1545. [DOI: https://dx.doi.org/10.1016/j.matpr.2020.03.802]