Additive Manufacturing of Complex Shapes Through Weld-Deposition and Feature Based Slicing

Abstract

Fabricating fully dense and functional metallic components is one of the important challenges in Additive Manufacturing (AM). Additive Manufacturing is a technology in which functional components can be fabricated rapidly and efficiently from their CAD models. It is also referred as Layered Manufacturing (LM) as the object is created by slicing the CAD model into layers and realizing each layer at a time. These layers are thin and stacked or glued together to get the physical shape of the CAD model. However, realizing overhanging features is a difficult task due to deficiency of support mechanism for metals. A separate support structure has to be deposited to build overhanging structures. Although, use of a distinct support material is quite common in non-metallic AM processes, such as Fused Deposition Modelling (FDM), and the same for metals is not yet available. The various techniques in AM process for fabricating metal parts can be mainly classified as laser based, electron beam based and arc based processes. While some Additive Manufacturing processes like Selective Laser Sintering (SLS) employ easily-breakable-scaffolds made of same material to realize the overhanging features, the same approach cannot be extended to deposition processes like laser or arc based direct energy deposition processes. Even though it is possible to realize small overhangs by exploiting the inherent overhanging capability of the process or by blinding some small features like holes, the same cannot be extended for more complex geometries. A different approach to solve this problem is feature based slicing. Unlike uniform and adaptive slicing techniques, where the thickness of a given slice is constant, in feature based slicing inclined slicing; the thickness varies even within a given slice, based on its feature. The current work presents a novel approach for realizing complex overhanging features without the need of support structures. This can be possible by using higher axis kinematics or by adding extra degrees of mobility to the work piece or to the deposition system and suitably aligning the overhang with the deposition direction. Some Vital concepts required in realizing and depositing overhangs are feature based non-uniform slicing and non-uniform area-filling and the same are briefly discussed here. This research will summarize the issues and related approaches in the research, development, and integration. This includes understanding of the weld deposition process by establishing proper geometries, and automated process planning. This technique can be used to fabricate or repair fully dense and functional components for various engineering applications. Although this approach has been implemented for weld-deposition based system, the same can be extended to any other direct energy deposition processes also.