Investigation of machinability of metal and fiber reinforced composites produced with different stacking orders

In this study, hybrid FML composite laminates with 5 different Al 2024/ FRP (12 layers)/ Al 2024 stacking sequences consisting of CFRP and GFRP layers were produced by vacuum bagging method. These materials were used in machinability tests (conventional drilling and abrasive water jet drilling) and mechanical tests (tensile test and low speed impact test). In conventional drilling, 4 different feed rates (100, 200, 300 and 400 mm/min) and 3 different speeds (1500, 3000 and 4500 rpm) were used. A 6 mm diameter tungsten carbide twist drill was used during drilling. Cutting force and torque values were determined with the dynamometer on the bench. Surface roughness measurements were made with Mitutoya 2D profilometer. In addition, the surface morphology was examined in detail by SEM analysis. In the abrasive water jet drilling process, 3 different traverse speed (400, 600 and 1000 mm/min) were used. Nozzle diameter, cutting pressure, amount of abrasive garnet and nozzle distance were kept constant. After drilling, inlet and outlet hole diameter, change in material thickness, kerf angle and hole deviation rate were determined. Surface roughness measurements were made with a Zygo optical profilometer. In addition, the defects occurring in the hole were shown in detail by SEM analysis. The effect of stacking sequence on both drilling methods and mechanical tests was comprehensively evaluated. As a result of the study, it was determined that the stacking sequence has a significant effect in both machinability methods. Hole damage was observed to be more intense in GFRP structures. The lowest surface roughness values were measured in stacks with fully CFRP structures. In hybrid composites, it was generally found that the GFRP structure increased the surface roughness.