Airflow performance of Ti6Al4V holes with varying surface characteristics induced by different machining methods

Purpose This study investigates how hole characteristics such as surface roughness, dimensional deviation and burr formation affect airflow performance in Ti6Al4V alloy. This work aims to inform better process planning and quality control strategies for components used in flow-sensitive applications such as aerospace and fluid systems. Design/methodology/approach To produce a representative range of hole qualities, four hole-generation techniques – Conventional Drilling, Drill + Reaming, Orbital Drilling and Wire Electrical Discharge Machining (WEDM) – were used. Each method inherently produced distinct features in terms of surface roughness, dimensional tolerance and burr formation. Findings The findings suggest that surface integrity and burr-free geometry significantly impact effective flow area, sometimes more than nominal diameter alone. In particular, holes produced via WEDM exhibited the most favorable flow performance due to minimal surface roughness and absence of mechanical deformation. Originality/value The findings underline the importance of surface and form integrity in functional applications where airflow is critical, providing insights for both manufacturing method selection and downstream quality control. The accepted surface roughness value in the turbine industry is Ra = 0.8 µm. The fact that the roughness values obtained in methods WEDM and Orbital Drilling applied in this study were 0.561 and 0.775 µm proved that this study meets the industrial requirements.