New trajectories in Electron Beam Melting manufacturing to reduce curling effect

Previously reserved to the manufacturing of prototypes, since few years, additive manufacturing is used to manufacture metallic parts. It is the case of the Electron Beam Melting (EBM) process that is studied in this paper. The transition from prototypes to functional parts has led to increase the requirements on the produced parts. The quality of the built material has to be controlled, the geometrical tolerancings decrease and the residual stresses try to be limited. This article will focus on current main quality problem: the deformations of the part during its built due to thermal effects. The aim of this article is to show the interest to use specific melting strategies, and especially specific beam trajectories to reduce these thermal effects. First the current solution to avoid these deformations (support structures) will be discussed. In a second part the thermal phenomena causing deformations of the part will be explained in order to propose a new strategy to limit deformations in the third part. This strategy is based on the modulation of the energy input using specific beam trajectories. (C) 2014 Elsevier B.V.