Metal Additive Manufacturing Conference 2018

Gases represent only a very small part of the production cost structure, but they play a crucial role for safety, process stability and for the final quality of products. Although the influence of the gas in the process is sometimes considered to be secondary during the laser beam melting process, its protective function is essential, as well as the evacuation of generated smokes and spatters in order to limit the pollution of the powder bed. In this work, our study on the influence of gas atmosphere on the process and on the quality of the manufactured parts is presented. Usually, argon or nitrogen is used to inert the chamber during the process. In this study, realized in collaboration with Poly-Shape company and the Process and Engineering in Mechanics and Materials laboratory (PIMM, Paris), various atmospheres have been studied including helium/argon mixtures as well as nitrogen with defined quality and from machine-integrated nitrogen generator. Modifications of the process have been observed, on the melt pool stability and wettability, and on the generation of particles and spatter. The atmosphere of the chamber has been controlled (oxygen, moisture and nanoparticles), powder and generated particles were analyzed and their impact on the part properties quantified.