From 3D Models to 3D Prints: an Overview of the Processing Pipeline <s> Optimize for mixed factors <s> Rapid prototyping (RP) machines reduce the lead time and cost of new products by automating the prototype manufacturing phase of the product development process. However, it is necessary for operators to orientate the prototype correctly in the RP machine to obtain the best trade-off between time, cost, and accuracy. The purpose of this work is to produce a decision-support tool to help RP users in this task. The tool is aimed at stereolithography which is the most widely adopted RP technology, The tool is a feature-based system produced using an object-orientated programming language and a solid modelling CAD environment. Cost, time, problematic features, optimally orientated features, overhanging area, and support volume are considered when recommending a build direction to the user. Three sample parts were used to illustrate the performance of the system. The system yielded the best surface finish and correctly highlighted several problem features. <s> BIB001 </s> From 3D Models to 3D Prints: an Overview of the Processing Pipeline <s> Optimize for mixed factors <s> Abstract Part orientation is an important parameter in the planning of a Rapid Prototyping (RP) process as it directly governs productivity, part quality and cost of manufacturing. This paper reports the design and implementation of a system for obtaining optimum orientation of a part for RP. Developed in a modular fashion, the system comprises of functional modules for CAD model preprocessing, shelling (hollowing), part orientation and optimization. CAD part model in STL format is an input to the system. The oriented CAD model is sliced and hollowed with desired shell thickness. Genetic algorithm based strategy is used to obtain optimum orientation of the parts for RP process. The objective criteria for optimization is considered to be a weighted average of the performance measures such as build time, part quality and the material used in the hollowed model. The developed system has been tested with several case studies considering SLS process. <s> BIB002
In BIB002 and [TPR04] two genetic algorithms to find the optimal part orientation are presented. They both formulate the subject of their optimization as a weighted sum of multiple quality criteria, regarding both cost and fidelity. The weights can be finely tuned by the user to set tune the importance of each criterion. Similar approaches have been presented in   , however these methods do not scale well with complex mechanical shapes (and non-mechanical shapes) as they consider a very restricted set of candidate orientations computed on the convex hull of the part. Decision support systems to aid RP users chose the best building direction according to their needs are presented in BIB001 and  . Both systems consider multiple criteria that can be prioritized according to the user needs, such as: overhang area, supports volume, build time and cost. On the negative side, these systems are specialized for CAD shapes and do not scale well on free-form shapes.