Feasibility of tool configuration and the effect of tool material, and tool geometry in multi-hole simultaneous drilling of Al2024

The use of the multi-spindle head in drilling technology can reduce the drilling cycle time by simultaneously producing multiple holes in one go. However, selecting the appropriate drill material and geometry is critical to overcoming the challenges of multi-hole drilling to ensure high-quality holes. This study investigates the use of the multi-spindle head with different tool configuration, tool materials and tool geometry during multi-hole simultaneous drilling of Al2024. A comparison is made among the high-speed steel drills (diameter: 6 mm; point angle: 118 degrees) and two different carbide drills (diameter: 6 mm and 10 mm; point angle: 140 degrees) as well as the maximum and minimum possible centre to centre tool distances of the multi-spindle head. The experiments are based on measuring the thrust force, evaluating the hole quality in terms of surface roughness and burrs, the formation of chips and post-drilling tool conditions. The results showed that carbide drills with high point angle and smaller diameter generated less thrust force, produced higher quality holes, and formed less built-up edge due to short chips. Besides, tools of the multi-spindle head can be adjusted in any position without affecting the hole quality which is useful for increasing productivity at a higher rate in manufacturing industries.