An improved fused deposition modeling process for forming large-size thin-walled parts

Aiming at the problem of severe warping, deformation and crack during the fabrication of large-size thin-walled parts, an improved fused deposition modeling process with laser-assisted heating was put forward to improve the forming quality and shape accuracy. The numerical model of the improved FDM process was established to analyze the thermal field and three-dimensional (3D) solidified morphology during the forming process. The dependency relationship among the forming temperature, shear rate and the thermo-physical properties of forming material, such as viscosity and surface tension, were considered in the model. The numerical model was verified by experiments from two aspects: the temperature information and the solidified morphology. The effects of forming speed, laser power and the ways of laser heating on the surface temperature distribution and viscosity of the forming material were investigated. Incremental forming experiments of ABS thin-walled parts was carried out under several laser irradiation conditions and forming speeds using the improved process. The results show that the lateral laser-assisted heating has more obvious effect in increasing the temperature of the local forming regions than the pre- and post-laser-assisted heating. Tensile strength of test unit had a maximum increase of 195% when the lateral laser-assisted heating was employed. Meanwhile, the shape accuracy of the fabricated thin-walled parts can be improved obviously, and the effective bonding width between layers was about 24% larger than that without laser-assisted heating.