Effect of powder supply preheating on mechanical properties and moulding accuracy of carbon black/pinewood/polyethersulfone composites printed by image shape laser sintering

Preheating in selective laser sintering plays a critical role in enhancing mechanical properties and dimensional accuracy. Due to equipment of image shape laser sintering limitations that prevent direct preheating of the build chamber, a thermal conditioning strategy was implemented in the powder supply chamber instead. To assess the impact of supply chamber preheating for image shape laser sintering on part strength and dimensional accuracy, this study systematically examined the effects of laser power (16–22 W), scanning speed (6–12 mm/s), layer thickness (0.1–0.25 mm), and preheating temperature (70°C–85°C) of carbon black/ pinewood/ polyethersulfone composites. Temperature calibration confirmed that the powder could be preheated to 85°C, maintaining a powder bed surface temperature of approximately 60°C during spreading. Orthogonal experiments, combined with a weighted performance analysis, showed that scanning speed had the most significant influence on mechanical and geometric outcomes, while layer thickness had the least. The optimal process parameters—20 W laser power, 85°C preheating temperature, 0.15 mm layer thickness, and 6 mm/s scanning speed—resulted in a twofold increase in tensile strength and a 1.5-fold increase in flexural strength compared to samples processed without preheating. These results highlight the effectiveness of indirect preheating and offer a practical solution for cases in which direct build chamber heating is not feasible.