Investigating Drilling Efficiency: A Study on Indexable Centerless Drilling of Ti-6Al-4V Alloy

Abstract Titanium Alloy (Ti-6Al-4V), is highly regarded in the aerospace industry due to its exceptional strength-to-weight ratio. The alloy's low thermal conductivity and high tensile strength pose machining challenges, leading to increased tool temperatures and mechanical stress. The conventional use of solid carbide drills is hindered by substantial tool wear. To improve tool life, prior research has delved into various cutting strategies, ranging from flood cooling to minimum quantity lubrication (MQL), enduring challenges persist. This study introduces an innovative approach, leveraging Titanium Aluminum Nitride (TiAlN) coated indexable centerless inserts to bore holes in Ti-6Al-4V under three distinct cutting conditions: dry, flood cooling, and MQL. These conditions are scrutinized across varied feed rates (60 mm/min, 100 mm/min, and 120 mm/min) with a fixed spindle speed of 1200 rpm. The study's primary focus is on key output parameters, including surface roughness (SR), tool life, and cutting temperature. From the parametric and surface topographic analysis, the findings reveal that under the flood cutting approach with a 60 mm/min feed rate, the indexable inserts excelled when drilling Ti-6Al-4V. This combination delivered a better surface quality (Ra = 1.66 µm), extended tool life (27814.27 mm 3 material removed and 18 holes drilled), and lower cutting temperature (881°F). Additionally, scanning electron microscopy (SEM) analysis corroborates that most common types of wear observed were abrasion, delamination, cracking, and edge fracture.