Browsing by Author "Rafighi, Mohammad"

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A Comparative Performance Investigation of Single- and Double-Nozzle Pulse Mode Minimum Quantity Lubrication Systems in Turning Super-Duplex Steel Using a Weighted Pugh Matrix Sustainable Approach
(2023) Roy, Soumikh; Kumar, Ramanuj; Panda, Amlana; Sahoo, Ashok Kumar; Rafighi, Mohammad; Das, Diptikanta; 0000-0002-9343-9607; AAQ-7933-2020
This study investigates the performance comparison of machining of UNS S32750 super-duplex stainless steel under single- and double-nozzle pulse mode minimum quantity lubrication (MQL) conditions. The pulse mode MQL system delivers lubricant pulses at specific intervals. The Taguchi L9 design, with three factors and their three levels, was taken to perform the CNC turning experiments under both single-nozzle and double-nozzle MQL cooling environments. The surface roughness (Ra), tool-flank wear (VB), tool-flank temperature (Tf), power consumption (Pc), and material removal rate (MRR) are evaluated and compared as performance indicators. In comparison to single-nozzle MQL, the responses of Ra, VB, Tf, and Pc were found to be decreased by 11.16%, 21.24%, 7.07%, and 3.16% under double-nozzle conditions, respectively, whereas MRR was found to be 18.37% higher under double-nozzle conditions. The MQL pulse time was found to be an important variable that affects Ra, VB, Tf, and MRR significantly. Under both cooling scenarios, common wears such as abrasion, built-up edges, adhesion, and notch wear are detected. Furthermore, the Pugh matrix-based sustainability evaluation results revealed that the double-nozzle MQL technique was superior to single-nozzle MQL, achieving improved sustainability for machining super-duplex stainless steel.
Exploring The Viability Of Alternative Cooling-Lubrication Strategies İn Machining Processes: A Comprehensive Review On The Performance And Sustainability Assessment
(Başkent Üniversitesi Mühendislik Fakültesi, 2024-02-19) Roy, Soumikh; Das, Anshuman; Kumar, Ramanuj; Das, Sudhansu Ranjan; Rafighi, Mohammad; Sharma, Priyaranjan
This paper explores the challenges of machining difficult-to-cut metals using tools like coated carbide, ceramics, and CBN under dry conditions, addressing issues such as heat generation, tool wear and friction, chip evacuation, surface integrity, vibration, and chatter. Though cutting fluids have historically improved machinability, environmental concerns, such as toxicity and non-biodegradability, are significant. Researchers aim to enhance the economic and ecological aspects of machining by reducing cutting fluid usage. This paper provides an overview of the performance assessment and sustainability evaluation of various cooling and lubrication methods during the machining of hard-to-machine as well as difficult-to-cut metals. Additionally, the literature review highlights various environmentally friendly cooling strategies, such as minimum quantity lubrication (MQL) and cryogenic arrangements. According to the results of this review, the utilization of various cooling and lubrication technologies has the potential to enhance both sustainability and machinability properties while prolonging the lifespan of cutting tools. The findings also show that there is a lot of room for improvement in terms of optimizing and making these cooling-lubrication solutions more practical and effective.
Material Gradation Effects On Twisting Statics Of Bi-Directional Functionally Graded Micro-Tubes
(AIP ADVANCES, 2024-03-04) Aghazadeh, Reza; Rafighi, Mohammad; Kumar, Raman; Al Awadh, Mohammed
This study aims to characterize the twisting behavior of bi-directional functionally graded (FG) micro-tubes under torsional loads within the modified couple stress theory framework. The two material properties involved in the torsional static model of FG small-scale tubes, i.e., shear modulus and material length scale parameter, are assumed to possess smooth spatial variations in both radial and axial directions. Through the utilization of Hamilton's principle, the governing equations and boundary conditions are derived, and then, the system of partial differential equations is numerically solved by using the differential quadrature method. A verification study is conducted by comparing limiting cases with the analytical results available in the literature to check the validity of the developed procedures. A detailed study is carried out on the influences of the phase distribution profile and geometric parameters upon twist angles and shear stresses developed in FG micro-tubes undergoing external distributed torques.