Investigation of machinability of nomex composite materials

The processing of Nomex composite materials, which are widely used in sectors such as aerospace, marine, motorsports and automotive due to their superior properties such as high strength, light weight and non-flammability, is complex due to their anisotropic structure. In such composites, which are joined with fasteners such as rivets and bolts, the quality of the drilling process is an important factor determining the quality of the connection. In this study, the delaminations caused by the cutting forces generated during the drilling process were investigated in order to determine the most suitable cutting tool geometry, spindle speed and feed rate. In the experiments, glass fiber prepreg coated Nomex honeycomb sandwich material; Helical three flute cutting tool and two flute breaker type cutting tools; 100, 200, 300, 400 and 500 mm/min feed rate and 2000, 8000 rpm. and spindle speed parameters of 2.000 and 8.000 rpm on a vertical machining center using the direct drilling method. Cutting forces were measured with a dynamometer. Delamination was calculated from the images of the drilled holes. As a result of the experiments, the best cutting force and exit delamination values were obtained at low feed rates with a two-flute breaker type cutting tool. Cutting forces decreased with higher spindle speed. High spindle speed increased the exit delamination values in the experiments with the two-flute breaker type cutting tool.