Optimisation of part orientation and design of support structures in laser powder bed fusion

Part orientation and support structures are crucial to the quality of metal parts by laser powder bed fusion. Computer-aided solutions for part orientation can be used to support users during the process preparation. In this study, an original computer-aided approach to prepare parts for laser powder bed fusion was formulated and implemented. The proposed method consists of multi-objective optimisation of part orientation and a novel strategy for the simultaneous design of support structures. The automated part orientation optimisation considers both global and local objectives defined by the user. For this purpose, penalty functions measuring the building time, support volume, part distortion, surface roughness and supports contact points are adopted. Unlike in existing methods, the user has the opportunity to define the importance of these aspects in different regions of the part. Such functions are then optimised through a genetic algorithm. The proposed approach was applied to a real product imposing three different sets of objectives. The tested case studies were solved in less than 10 min, providing solutions that satisfied the imposed aims and constraints. Specifically, the results demonstrated that the orientation optimisation can reduce the building time by 68.1% or the material consumption by 66.8%, depending on user requirements. It was also shown how the proposed method can be used to minimise the surface and dimensional error of manufactured parts. The proposed approach allows to manually define the specific design requirements and translate them in terms of manufacturing decisions. This contributes to establishing a fruitful interaction between the user and the developed software during the process design.