Formability Assessment of 3D-Printed Acrylonitrile Butadiene Styrene Sheets Using Nakajima Test

This study explores the formability of acrylonitrile butadiene styrene (ABS) sheets produced by the fused filament fabrication 3D-printing process. The ABS sheets, fabricated with a diameter of 80 mm, were subjected to the Nakajima test. The investigation focused on assessing the impact of printing pattern (rectilinear, concentric, concentric/rectilinear), sheet thickness (0.8, 1.4, and 2 mm), and forming temperature (35, 70, and 90 °C) on forming depth, utilizing a full factorial design of experiments comprising 27 conditions. Through the application of analysis of variance, a model was developed to predict forming depth, demonstrating high precision and reliability. Results indicate that as temperature increases, formability improves, reaching a maximum at 90 °C with a rectilinear print pattern (15.95 mm depth). Conversely, the lowest forming depth (1.45 mm) occurred at 35 °C with a concentric printing pattern. Sheet thickness exhibited a minimal impact on forming depth, indicating that while thicker sheets do lead to a slight increase in depth, the effect is relatively minor. However, the forming force significantly increased with thickness.