Aluminum Matrix Composite (AMC) represents an innovative class of materials that is extensively utilized in industries such as automotive, defense, aerospace, structural engineering, sports, and electronics. This study investigates the thrust force, exit burr formation, changes in the micro-tool, and drilled hole diameters during the micro-drilling of an aluminum-polyethylene composite panel (Al–PE). The panel consists of 3501 series aluminum skin materials bonded to a polyethylene (PE) core. Micro-drilling test parameters were designed using Taguchi’s L16 (4² 2³) orthogonal array. Tests were conducted with five control parameters: cutting speed with four levels (10 m/min, 20 m/min, 30 m/min, 40 m/min), feed rate with four levels (0.5 µm/rev, 1 µm/rev, 2 µm/rev, 4 µm/rev), the tool diameter with two levels (0.7 mm, 1 mm), and tool point angle with two levels (100°, 140°) using both AlTiN-coated and uncoated drills. The maximum thrust force (F_z), maximum burr height, and changes in both the drill tool and hole diameters were measured for analysis of variance (ANOVA). The results showed that, in terms of impact on F_z, tool point angle had the highest positive influence (64.54%) on the micro-drill at the entrance of composite (upper aluminum plate). The cutting speed had the highest positive influence (45.32%) on the tool in the core layer (PE core layer). The tool point angle also had the highest positive influence (68.95%) on the micro-drill at the lower layer of the composite (the lower aluminum plate). There was noticeable chip adhesion on the major cutting edge and nose area under micro-drilling conditions with higher thrust forces and burr height. The AlTiN coating had a positive effect on tool wear and hole diameter deviations, but it adversely affected the burr height.

This study investigates the combined effects of drilling parameters and tool features on thrust force during drilling of hybrid AA7050/CFRP stacks intended for aerospace applications. Experiments were designed using a Taguchi L16 (4²2²) orthogonal array by considering feed rate, cutting speed, drill diameter, and coating condition. Unlike most previous studies on Al/CFRP stack drilling, this work provides a layer-specific evaluation by separately analyzing the thrust-force responses of the AA7050 and CFRP layers, while also correlating force behavior with aluminum-side damage and CFRP-side delamination within a unified framework. For the aluminum layer, feed rate was the dominant factor affecting thrust force, with a contribution of 71.22%, followed by drill diameter (26.22%). For the CFRP layer, drill diameter was the most influential parameter (52.58%), followed by feed rate (43.77%). Thrust force ranged from 155.24 to 414.45 N for AA7050 and from 77.73 to 175.39 N for CFRP. Uncoated tools and higher feed rates increased thrust force, leading to poorer machining performance. Delamination in the CFRP layer was primarily governed by feed rate (46.71%), followed by drill diameter (35%). Overall, increasing feed rate and drill diameter significantly deteriorated the machinability of the hybrid structure.