Investigation of machinability in carbon fiber reinforced composite pipes with epoxy polymer matrix produced in different fiber directions

Today, the search for high-strength and lightweight materials continues rapidly, especially to use the developing battery systems more efficiently. For this reason, composite materials are attracting more attention. Composite materials are obtained from two or more materials and contain the superior properties of these materials. Fiber reinforcement plastics (FRP) are used in a significant number of high-tech applications. For example, it is used in the maritime, aviation, motor sports, energy, and defense industries. However, some challenges remain to be overcome, such as long production times, high production costs, and difficulties in complex geometries. Although various production methods such as filament winding, pultrusion, and vacuum bagging are available to obtain products in shaped geometries, the hand lay-on-die method is the most efficient method for developing high-strength materials. In the thesis study, carbon fiber and polymer matrix were studied. Since surface sensitivity is low in the production methods of CFRP pipes, surface quality treatments are required at the end of production. Considering these processes, the turning machining process for CFRP pipes has been experimentally investigated in this study. In this study, products were obtained by using unidirectional fiber direction (UD) fiber in the manufacture of carbon fiber/epoxy composite pipes; and by winding at angles between 0, 45, and 90° for application-oriented use. The produced samples were turned at three different cutting speeds, three different feed rates, and constant cutting depth on a computer numerically controlled (CNC) lathe. After the turning process, surface roughness, cutting temperature, and tool wear parameters were investigated. As a result of the experimental studies, the highest surface roughness value was reached at 90⁰ wrap angle and 120 m/min cutting speed, and the lowest was reached at 45⁰ wrap angle and 160 m/min cutting speed. As for the cutting temperature, it was observed that as the cutting speed increased, the cutting temperature also increased.