STEP-based approach for direct slicing of CAD models for layered manufacturing

Direct slicing can generate precise slice contours from original CAD models and obviates the error-detection and repairing process of STL files. At present, most direct slicing approaches are restricted to some CSG solids or particular CAD packages. In this paper, an approach for direct slicing of CAD models based on STEP for layered manufacturing is presented. The original CAD model is first transferred from CAD systems to the slicing system by neutral STEP files. Using OpenGL graphics libraries, the solid model is then displayed, and the user is prompted to specify the layer thickness. Finally, the CAD model is sliced directly, and the sliced model is exported by SSL (Stratasys Layer interface files) file format which can be sent to many kinds of layered manufacturing systems for direct fabrication. The approach of STEP-based direct slicing is more flexible and does not rely on any specicfic CAD system; in addition, the STEP files are much smaller than the STL files. Implementation details and results are also presented.