Optimization of Pultrusion Process Parameters for Carbon Fiber/Epoxy Composites

This study investigates the effects of key pultrusion process parameters—including temperature profile, fiber volume ratio (FVR), preformer geometry, resin viscosity, and line speed—on the production stability and mechanical performance of carbon fiber/epoxy composite profiles. Continuous carbon fiber rovings were impregnated with epoxy resin and processed through a multi-zone heated die under varying operating conditions. Tensile properties were evaluated in accordance with ASTM D3039 to ensure standardized and comparable mechanical characterization. Experimental observations revealed that even small adjustments in thermal management, heating zone positioning, preformer compression and eye diameter, fiber volume ratio, resin rheology, fiber type, squeezer configuration, and pulling speed produced significant variations in surface quality, flow behavior, resin backflow, fiber congestion, and overall process stability. The optimal process window was achieved at a line speed of 30–35 cm/min and an FVR range of 65–70%, with improved results obtained by shifting the initial heating zone backward, reducing the final preformer diameter, and utilizing lower-viscosity resin systems. The findings provide a comprehensive process–property relationship for carbon pultrusion and offer a practical guideline for industrial optimization aimed at achieving stable production and high-quality composite profiles.