Effect of high-pressure hot airflow on interlayer adhesion strength of 3D printed parts

A novel gas-assisted FDM 3D printing method is proposed in this study. High-pressure hot airflow is injected into a special designed 3D printing nozzle to form a thin gas film between molten polymer and nozzle wall, so the die swell effect of polymer is eliminated. The high-pressure hot airflow heats and pressurizes the printed part surface, which improves the inter-layer adhesion strength. To form a stable thin gas film, the gas temperature, gas flow, and gas pressure are studied. The results show that under conditions of 210 degrees C, 1.75 L/min, and 0.4 MPa, a stable gas film is formed between the inner wall of gas-assisted nozzle and molten polymer. The inter-layer adhesion strength of the printed parts is enhanced more than 50%, and the lowest dimensional shrinkage is only 0.13%. The developed gas-assisted 3D printing nozzle improves the performance of parts and provides new possible applications in biomedical, automotive, aerospace, and functional device printing.