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    Heat Transfer Efficiency of Cryogenic-LN2 and CO2-snow and their application in the Turning of Ti-6AL-4V
    (Pergamon-Elsevier Science Ltd, 2021) Jamil, Muhammad; He, Ning; Zhao, Wei; Li, Liang; Gupta, Munish Kumar; Sarikaya, Murat; Khan, Aqib Mashood
    Owing to poor thermal conductivity, and high chemical reactivity of Ti-6Al-4V alloy at elevated temperatures, a lubri-cooling having superior heat transfer is benefic to apply to dissipate cutting heat and to improve the machinability. As conventional coolants are ineffective to prevent thermal damage and tool wear. Therefore, recent advanced cryogenic coolants such as cryogenic-liquid nitrogen (LN2) and carbon dioxide (CO2-snow) are hypothesized to mitigate the set objectives. In this experimental study, a static workpiece plate was sprayed to compare their heat transfer coefficients. Furthermore, the machining performance of cryogenic coolants was evaluated in the turning of Ti-6Al-4V in terms of tool wear, cutting force, surface roughness, and chip curl diameter. For this, experiments are conducted at a constant cutting speed of 120 m/min, a feed rate of 0.1 mm/rev, the coolant injection flow rate of 350, 450g/min, and a depth of cut of 2.5 mm to clarify their effect on the process. The outcome analysis of this work showed the overall less tool wear, cutting forces, surface roughness, with maximum chip curl diameter under CO2-snow cooling followed by cryogenic-LN2 and dry condition. In summary, CO2-snow showed promising outcomes and a superior heat transfer effect warrant its implementation in the aerospace industry. (C) 2020 Elsevier Ltd. All rights reserved.
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    Sustainable milling of Ti-6Al-4V: A trade-off between energy efficiency, carbon emissions and machining characteristics under MQL and cryogenic environment
    (Elsevier Sci Ltd, 2021) Jamil, Muhammad; Zhao, Wei; He, Ning; Gupta, Munish Kumar; Sarikaya, Murat; Khan, Aqib Mashood; Sanjay, M. R.
    The urgent need for an innocuous and sustainable machining system is essential in this modern manufacturing era. Therefore, a study is devoted to fulfilling a missing bridge between sustainability measures (process time, specific cutting energy, energy efficiency, carbon emissions) and machining characteristics (tool wear, surface roughness, cutting temperature) in the milling of Ti-6Al-4V. The experiments are organized by implementing the minimum quantity lubrication (MQL), CO2-snow, and cryogenic-LN2 under varying end-mill geometries and cutting conditions. The results obtained have underscored the outperformed CO2-snow followed by cryogenic-LN2, MQL, and dry cutting conditions regarding sustainability measures and machining characteristics. The up-milling of 42 degrees helix angle cutter and CO2-snow outperformed by reducing 47% of surface roughness, 50% extended tool life compared to dry cutting. The cryogenic-LN2 provided minimum cutting temperature flowed by CO2-snow, MQL, and dry cutting, respectively. Besides, the up-milling tool of the 42 degrees helix angle provided better machining characteristics than the down-milling tool of the 30 degrees helix angle. The feasibility of CO2-snow was comprehensively expressed and implemented in the milling process to extend the advanced analysis. (C) 2020 Elsevier Ltd. All rights reserved.