# Sustainability-Based Analysis of Conventional to High-Speed Machining of Al 6061-T6 Alloy
## 2 Materials and Methods  
Despite the development of new materials in the last decade, the global consumption map of metals is dominated by steel and aluminum [33]. Low energy requirement in secondary production, abundance, and recyclability makes aluminum and its alloys the most environmental friendly metals [34]. Aluminum alloy 6 xxx series has excellent mechanical properties and is widely used in manufacturing of various components in automotive, aerospace, and other high-tech applications; therefore, aluminum alloy Al 6061-T6 has been employed as workpiece material in the current work. Turning operation of solid Al 6061-T6 shafts having diameter of 280 mm was performed on YIDA ML-300 CNC machine as shown in Figure 2. Cutting tests were performed with H 13 grade uncoated plain inserts without chip breaker (CCMW 09 T3 04-H13A) and tool holder (SCACL 1616 K 09-S). The cutting tool had 0\({}^{\mathrm{o}}\) rate angle, 90\({}^{\mathrm{o}}\) entry angle, nose radius of 0.4 mm, and a cutting edge length of 9 mm. In order to eliminate the effect of tool wear on energy consumption, fresh cutting edge was used in each experiment. Power measurements were done using Yokogawa CW-240 power analyzer. Specific cutting energy was measured as the ratio of the difference of power consumed in actual cut (\(P_{actual}\)) and air cut (\(P_{cut}\)) to the material removal rate (\(MRR\)), using the methodology described in previous research [11]. Surface roughness was measured using surface roughness tester TR 110. Three readings were taken around the circumference of aluminum shaft for each experimental run to minimize experimental error. The mean of the three values was taken as the final value, using the methodology described in the literature [35]. Figure 2: Turning setup used in present research. Several factors affect turning operation such as machining parameters (cutting speed, feed, and depth of cut), tool geometry, cutting fluids, and workpiece material. Since energy analysis was the focal point of this research, screening of factors was conducted based on detailed literature review. Tool geometry is highly significant for surface roughness, but its effect on power and energy consumption has been reported to be negligible [5; 36; 37]. Therefore, tool geometry was not varied during experimentation. A fresh cutting tool was used in every experiment to eliminate the effect of tool wear. Dry machining conditions were used for each experiment in order to realize the aspect of cleaner machining practices [19]. A detailed review of published literature revealed that cutting parameters such as cutting speed (\(v\)), feed (\(f\)), and depth of cut (\(d\)) have significant effect on power and energy consumption [16; 17; 38]. These three cutting parameters are also important because of their significant effect on cutting temperatures, production time, surface roughness, tool life, etc. [32; 39]. Therefore, cutting speed (\(v\)), feed (\(f\)), and depth of cut (\(d\)) were used in present work. Cutting speeds for different alloys can be generally divided in three regions: conventional, transition, and high-speed machining, as shown in Figure 3[40]. For aluminum alloys, conventional speed machining (CSM) range is approximately equal to 10-500 m/min. Transition speed machining (TSM) range, which is considered as a transition region between conventional and high-speed machining (HSM), is approximately equal to 500-1500 m/min. The HSM range for aluminum-based alloys can be described between 1600 and 10,000 m/min, with the upper bound dictated by tooling and machine tool limitations [41]. However, HSM is not just about increased cutting speeds; the feed and depth of cut are also required to be set at values higher than the usual practices [41; 42]. Feed (\(f\)) and depth of cut (\(d\)) are generally set at 0.05 mm/rev-0.3 mm/rev and 0.5-3 mm, respectively, during machining of Al 6061-T6 [16; 17; 43; 44]. In order to match for HSM, these two parameters were also set at values higher than the usual practice.