Effect of nozzle vibration at different frequencies on surface structures and tensile properties of PLA parts printed by FDM

•Proper vibration frequency of the nozzle increased the vertical tensile strength of FDM parts.•The vibration frequency determined the surface structure of FDM parts.•Nozzle vibration reduced the porosity of FDM parts. Fused deposition modeling (FDM) has been a widely used 3D printing technology. However, the poor inter-layer bonding strength leads to serious anisotropy, which hinders the further application of FDM technology. In this paper, a self-developed print head that vibrates the nozzle vertically was used to study the possibility of improving the vertical tensile strength of FDM parts, and to seek the appropriate vibration frequencies. The polylactic acid (PLA) specimens were printed at five different vibration frequencies and in two directions (horizontal and vertical). The results show that different vibration frequencies lead to different surface structures and porosities. The vertical tensile strength was increased when the vibration frequency was high enough. Moreover, vibration did not affect the horizontal tensile strength of FDM parts. This research is significant to promote the application of FDM technology.