Optimization and prediction of thrust force, vibration and delamination in drilling of functionally graded composite using Taguchi, ANOVA and ANN analysis

Composite materials offers many advantages over traditional materials in terms of weight, strength and design flexibility. However, machining of these materials leads to some critical problems such as delamination, inferior surface finish and excessive tool wear due to their anisotropic and inhomogeneity structure. In particular, in manufacturing of the functionally graded composite (FGC) materials, this situation becomes more complicated since these composites have been made with different stacking sequences. In this work, drilling performance of FGC, depending on delamination, thrust force and vibration, has been investigated experimentally by using different cutting parameters, which are feed rate, spindle speed and material directions (carbon/epoxy and glass/epoxy). From the results of experiments, the material direction has deeply affected the delamination (89.5%) but has rarely affected the thrust force (0.1%) and vibration (8.4%). Feed rate is the most impactful factor on thrust force and vibration generation. Whereas the feed rate has a direct proportion to the thrust force and delamination, the spindle speed has an inverse proportion to these responses. When the results evaluated generally, In addition to that, a surrogate model is created through ANN to estimate the responses or cutting parameters on the drilling process in a wider range.