Comparative Evaluation of Concentric and Helical Multipass Toolpath Strategies on Surface Integrity in CATIA V5-Based Pocket Milling of Al6061

The fabrication of aerospace components with thin-walled pocket features requires strict control of surface integrity, as surface roughness directly affects structural performance and fatigue life. However, the selection of appropriate toolpath strategies in computer-aided manufacturing (CAM) environments remains a critical challenge, particularly when multiple strategies are available for achieving similar geometric outcomes. This study investigates the influence of two roughing toolpath strategies namely Concentric-Multipass and Helical-Multipass, on surface roughness during pocket milling of Aluminum 6061 using CATIA V5. All experiments were conducted under constant machining parameters on a 3-axis CNC milling machine to ensure a consistent basis for comparison. Surface roughness (Ra) was measured using a Mitutoyo SJ-410 surface tester, while optical microscopy was employed to examine the resulting surface morphology. The analysis was performed across circular and rectangular regions to account for geometric variability. The results demonstrate that the Concentric-Multipass strategy consistently outperformed the Helical-Multipass approach in terms of surface finish. A minimum Ra value of 0.3145 µm and a maximum of 0.655 µm were recorded for Concentric-Multipass, whereas Helical-Multipass exhibited a higher peak roughness of 1.392 µm. Overall, the Concentric strategy achieved approximately 20–50% improvement in surface quality. Microscopic observations further revealed more uniform tool marks and reduced surface defects for the Concentric approach, indicating more stable cutting conditions. These findings highlight the critical role of toolpath selection in achieving high-quality surface finishes and suggest that the Concentric-Multipass strategy is more suitable for aerospace pocket milling applications requiring superior surface integrity.