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Article Comparative Analysis of Vibration Axis Effects on Ultrasonic Vibration-Assisted Machining of Inconel 718(MDPI, 2026) Namlu, Ramazan Hakki; Kilic, Zekai MuratInconel 718 is widely utilized in critical engineering sectors, particularly aerospace, owing to its exceptional creep resistance, corrosion resistance, and retention of mechanical strength at elevated temperatures. However, its high hardness, low thermal conductivity, and strong work-hardening tendency make it extremely difficult to machine using conventional techniques. Ultrasonic Vibration-Assisted Machining (UVAM) has emerged as an effective strategy to overcome these limitations by superimposing high-frequency, low-amplitude vibrations onto the cutting process. Depending on the vibration direction, UVAM can significantly change chip formation, tool-workpiece interaction, and surface integrity. In this study, the influence of three UVAM modes-longitudinal (Z-UVAM), feed-directional (X-UVAM), and multi-axial (XZ-UVAM)-on the machining behavior of Inconel 718 was systematically investigated. The findings reveal that XZ-UVAM provides the most advantageous outcomes, primarily due to its intermittent cutting mechanism. Compared with Conventional Machining (CM), XZ-UVAM reduced cutting forces by up to 43% and areal surface roughness by 37%, while generating surfaces with more uniform topographies and smaller peak-to-valley variations. Furthermore, UVAM enhanced subsurface microhardness as a result of the surface hammering effect, which may improve fatigue performance. XZ-UVAM also effectively minimized burr formation, demonstrating its potential for high-quality, sustainable, and efficient machining of Inconel 718.Article Citation - WoS: 1Citation - Scopus: 1An Experimental Study on Ultrasonic-Assisted Drilling of CFRP Composites with Minimum Quantity Lubrication(MDPI, 2025) Namlu, Ramazan Hakki; Sagener, Mustafa Burak; Kilic, Zekai Murat; Colak, Oguz; Kilic, Sadik EnginThe increasing use of carbon fiber reinforced polymer (CFRP) composites in industries such as aerospace, due to its high strength-to-weight ratio, durability, and resistance to corrosion has led to a growing demand for more efficient machining processes. However, the multilayered structure of CFRP composites, composed of densely packed fibers, presents significant challenges during machining. Additionally, when cutting fluids are used to improve effective cooling and lubrication, the material tends to absorb the fluid, causing damage and leading to problem of weaking of composite structure. To address these issues, this study compares ultrasonic-assisted drilling (UAD) and minimum quantity lubrication (MQL) techniques with conventional drilling (CD) and dry cutting to improve the performance of CFRP composite drilling. The results show that using UAD and MQL together reduced thrust force by up to 27%, improved surface roughness inside the holes by up to 31%, reduced improved hole diameter, cylindricity, roundness, and delamination.
