Support removal is one of the thorny issues faced by laser powder bed fusion (LPBF). In particular, the efficient and safe removal of support structures from the thin-walled parts and obtaining high-quality surfaces still remains a challenge owing to their sensitivity to machining. An in-depth understanding of the material response behavior of LPBF thin-walled parts when removing support structures is necessary for overcoming this challenge. The work is divided into two parts: revealing the support removal mechanism and proposing a solution to improve the support machinability. First, the machinability of support structures on thin-walled parts with different thicknesses at different cutting depths was thoroughly investigated. Experimental investigation on cutting force, surface morphology, and deflection were carried out. The results show that cutting forces increase gradually at each cut owing to the tilt and collapse of support structures. The surface morphology is improved as the sample thickness increases but deteriorated as the cutting depth increases. Second, a novel solution of adding resin is proposed to improve the support machinability and good results have been achieved. The z-direction cutting forces for 0.3 and 0.4 mm thickness samples are reduced by 72.6% and 64.6%, respectively, and no deflection of the sample is observed after support removal. Moreover, finite element method simulations are established to further explain the support removal mechanism.
Keywords: laser powder bed fusion; postprocessing; support removal; thin-wall structure.
Copyright 2023, Mary Ann Liebert, Inc., publishers.