Solid Freeform Fabrication (SFF) technologies refer to the fabrication of physical parts directly from computer-based solid models by layers using a row-by-row pattern, though it is possible to build the part using other patterns. The trend is to produce parts of 100% density which would have properties similar to those made by casting molten metal into a mold. Very good results have been obtained recently by treating a rendered part in a high pressure chamber. In this paper, an idea is presented in which the structure of a part can be designed in such a way that there is no need for the entire part to be 100% solid. The stresses are taken only by certain regions of structure and those regions should be rendered with full a density as possible. The rest of the part material is treated as filling and supporting substance which can be made as porous as is needed to conduct the heat out during the rendering process. In such an approach the design process for SFF technology would represent a challenge to designers who, in addition to making decisions concerning optimum shape and functionality of the entire part, have to take under consideration several other manufacturing factors. These factors cover a wide range of technical issues, such as Computer-Aided Design model generation, part description and model slicing files, laser path files, precision of part design, rendering patterns, manufacturing tolerances, thermal expansion, and residual stress phenomena.

On the basis of experience gained in previously developed SFF part manufacturing, the authors describe the concepts and some conclusions from the research in progress that concentrates on two areas that are inseparable; developing the most suitable CAD methods for precise part design, and optimization of the part building structure for maximum part stiffness under a given load.

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