A novel approach to fabricate uni-directional and branching slender structures using laser-based direct metal deposition

The slender structures are identified by a distinctive morphology and large aspect ratio. Contrary to most of the common products, the fabrication of slender structures is usually based on forming operations. For complex shapes; however, machining may be required. Characteristic of machining for a slender structure; however, is the very small ratio of sustained material with respect to the machined material. This paper describes a novel approach to fabricate slender structures using laser-based direct metal deposition (LBDMD) in a layer-by-layer fashion such that the thickness of each layer is infinitesimally small. The existing additive layer-by-layer deposition is guided by 2 1/2 axis movement and is characterized by intermittent steps. The proposed method, on the contrary, is similar to continuous 2 casting such that the layer thickness can be considered infinitesimally small. The paper develops a framework for fabrication of slender structures using LBDMD. An algorithm based on geometric reasoning is proposed. Simulations based on Volume Of Fluid (VOF) method and a set of experiments are performed to determine and control various key process parameters. Simulations and experiments performed to determine the a relationship between the material flow rate and corresponding body forces that act on the molten pool as the inclination of substrate changes. A range of complex geometries that are based on linear as well as nonlinear spatial trajectories are fabricated. The fabricated geometries offer different inclinations as well as material flow rate; hence, support the applicability of proposed method. (c) 2006 Elsevier Ltd. All rights reserved.