Application of FBG Technology in Additive Manufacturing: Monitoring Real-Time Internal Temperature of Products

This study presents an investigation of the influence of infill density on inner temperature change of Polylactic Acid (PLA) and carbon fiber filaments. Five groups of different infill densities (20%, 40%, 60%, 80%, and 100%) were considered for testing and analysis in additive manufacturing. Fiber Bragg grating (FBG) sensors were used to monitor the internal temperature change of all prototypes during additive manufacturing process. Monitoring tests indicate that relationships of temperature against printing time are characterized by three typical parameters including the first peak temperature (FPT), minimum temperature (MT), and completion temperature (CT). All FPT, MT, and CT values increase substantially as the increase of infill density values. MT values generally present at relatively lows infill density values but coincide with CT values at high infill density values. At low infill density levels (infill density is no higher than 60%), fabrication of the upper surface of prototypes leads to substantial temperature rise, and this rise appears to be limited at infill density values of 80% and 100%. This study can be used to reveal printing quality of 3D printed products arise from non-uniform distribution of temperature change.