Topology optimization based channel design for powder-bed additive manufacturing

Additive manufacturing (AM) technology allows us to manufacture 3D models with arbitrarily complex shapes. Among different AM technologies, powder-based 3D printing techniques, such as laser-based powder bed fusion of metals and polymers (PBF-LB/M and PBF-LB/P), are common tools favored by engineers and have been widely used in the industrial field. In order to reduce the cost of printing materials, a large variety of lightweight infill structures have been proposed, such as skin-frame structures, lattice structures, honeycomb structures and porous structures. Currently, most of the proposed methods lead to a large number of closed voids in the printed models. These closed voids are particularly detrimental to structures printed using powder-based 3D printing techniques. A large amount of powder remains in the closed voids and cannot be discharged, which will reduce the performance of the printed structure. This problem limits the application of powder-based 3D printing techniques for printing complex structures. To the best of our knowledge, very few investigations have been conducted to address this problem. In this paper, a method based on topology optimization (TO) is proposed to automatically generate channels between closed voids and outlets, by which the remaining powder of the powder-based printing structures can be discharged. The proposed method consists of three main steps: 1) topology optimization, 2) topology extraction, 3) channel generation. Six standard structures with a large number of closed voids are investigated to demonstrate the applicability of the proposed method. In addition, experimental tests are conducted to validate the effectiveness of the generated channels.