Investigation of deviations caused by powder compaction during 3D printing

Powder bed based 3D printing technologies are of great interest for the production of prototypes and low quantity production lots because they allow the realization of highly customized and complex geometries. Moreover, significant benefits of 3D printing include an expedited manufacturing and a decreased number of necessary tools in the process chain. In contrast to traditional production methods, where material is subtracted or molded, thin layers of powder are successively added and solidified by locally applying binder based on a digital model. By continuously depositing material, the powder bed experiences an additional compaction through the increasing weight of the material on top. The consequences are dimensional deviations of the component in build-up direction and occasionally even avalanche-like collapses of material. The objective of this study is the investigation of these effects and their influencing factors. For this reason, occurring deviations and their underlying causes are examined. Test objects were manufactured and examined with the objective of identifying the main influencing factors by varying the length, position and surrounding conditions of the objects within the building chamber. Significant parameters were analyzed in greater detail in order to generate rules, regarding their effect on the occurrence and magnitude of the identified deviations. Finally, an approach for the compensation of these deviations prior to the production by a pre-deformation of the digital model was implemented. (C) 2016 The Authors. Published by Elsevier B.V.