Determining fabrication orientations for rapid prototyping with stereolithography apparatus

Traditionally, prototypes are built manually by skilled workers with the help of machine tools, which is very time consuming. The advent of rapid prototyping technology greatly eases the effort required for making prototypes. In this research we investigate geometric issues involved while using a particular rapid prototyping system, called Stereolithography Apparatus (SLA). SLA creates prototypes layer by layer, each layer being formed (solidified) by scanning a laser beam across the x-y surface of a vat of liquid monomer mix. In contrast to traditional methods, the planning of prototyping with SLA is done directly with the computer models of designed parts and requires little experience. The performance of SLA is influenced by the orientation in which a design is fabricated. For example, sloped surfaces produced by the SLA process inherently have an undesirable stepped surface texture. Such surface texture can, however, be reduced by orienting as many faces as possible vertically or horizontally. This prompts us to establish decision criteria and develop algorithms-based on the considerations of surface quality, build time, and the complexity of support structure-for identifying desirable fabrication orientations for a given design. Copyright (C) 1996 Elsevier Science Ltd