Rapid Prototyping by Laser Foil Bonding and Cutting: Thermomechanical Modeling and Process Optimization

Abstract

This paper introduces a new solid freeform fabrication technology based on successive joining of thin metal foils by laser spot welding, followed by laser cutting of each layer contour. This technology was implemented in the laboratory using a robotic Nd:YAG laser station with optical fiber transfer, and the optimal bonding and cutting conditions were determined experimentally for steel prototypes. A flexible thermomechanical finite element model of the process was established, with its boundary conditions calibrated and its predictions verified by pyrometry and profilometry measurements. This numerical model was used to study the layer deformation due to thermal gradients and to develop weld sequencing, cycle timing, and in-process heat treatment methods for minimization of warping distortions and residual stresses. This new rapid manufacturing technology can fabricate high-strength, high-density multi-metal parts and metalmatrix composites as well as internal functional structures with encapsulated active components.