Current commercial rapid prototyping technologies are based on a layered additive process to build parts. The layer-based process results in a stairstepping effect, which can be apparent on curved and sloped surfaces. The selection of the build orientation, whether based on experience, trial and error, or not even considered, is one critical factor that affects the quality of the surface finish. Furthermore, it influences other important aspects, such as the build time and the amount of support structure needed. The authors propose an expert system tool that considers the various parameters that affect the production of the prototype and interacts with the user to recommend the best direction to build. The recommendation is based both on the user's input and on a decision matrix based on the result of interviews with experts, which is implemented within the expert system. If an optimal orientation is not possible, the tool helps the user to select an acceptable build direction. The expert system can also draw attention to issues such as trapped volumes, which can be detrimental to the build process. It helps to reduce the design time, to automate the build process and to minimize the cost of the prototype. The results of this work form a base for ongoing research to complete a tool that considers all major issues for a preferred orientation.
