Optimization of turning parameters to minimize surface roughness and tool wear in carbon fiber and glass fiber composite rods

The objective of this research is to optimize the cutting parameters for reduced surface roughness and tool wear in turning carbon fiber (CFRP) and glass fiber (GFRP) composite rods. Experiments were conducted under dry machining with a Taguchi L8 orthogonal array, and effects of cutting speed, feed rate, depth of cut, together with coated cutting insert were studied. Taguchi analysis as well as regression models and desirability function approach were utilized in assessing the impact of parameters on output such as average surface roughness (Ra), tool wear, including cutting time. The findings revealed that different optimum parameter combinations for CFRP and GFRP; for surface roughness in CFRP, coated tools with 120 m/min cutting speed, 0.2 mm/rev feed rate and 0.5 mm depth of cut provided the lowest surface roughness (2.240 µm), while in GFRP, coated tools with 150 m/min cutting speed, 0.2 mm/rev feed rate and 0.5 mm depth of cut provided the lowest surface roughness (3.557 µm). For tool wear, uncoated tools with 150 m/min, 0.2 mm/rev and 0.8 mm in CFRP (22 µm) and uncoated tools with 60 m/min, 0.2 mm/rev and 0.8 mm in GFRP (25 µm) gave optimum results. Moreover, the seventh experiment (150 m/min, 0.2 mm/rev, 0.8 mm, uncoated) presented the optimum balance with low surface roughness, tool wear and cutting time. This work showed that CVD TiCN+Al₂O₃ coating type was inadequate against the abrasive nature of composite materials and was not suitable due to problems such as peeling style deformation. Results were obtained that GFRP has higher surface roughness compared to CFRP, supporting the hypothesis of fiber pull-out tendency of glass fibers and low thermal conductivity stated in previous literature. The study aims to provide a practical guide to improve the efficiency and quality of processing these composites in industrial applications.