Process-planning for layered manufacturing of heterogeneous objects using direct metal deposition

Layered manufacturing (LM) is emerging as a new technology that enables the fabrication of three-dimensional heterogeneous objects such as multimaterials and functionally gradient materials (FGMs). The necessary steps for LM fabrication of heterogeneous objects include representation and process planning of material information inside an object. This paper introduces a new processing planning method that takes into account the processing of material information. The detailed tasks are pre-processing (discretization), orientation (build direction selection), and adaptive slicing of heterogeneous objects. In particular, this paper focuses on the discretization process that converts all of the material information inside a heterogeneous object into material features like geometric features. It is thus possible to choose an optimal build direction among various preselected ones by approximately estimating build time. This is because total build time depends on the complexity of features. This discretization process also allows adaptive slicing of heterogeneous objects to minimize surface finish and material composition error. In addition, tool path planning can be simplified into fill pattern generation. Examples are shown to illustrate the overall procedure.