Process modeling for projection based stereo lithography
Stereo lithography is a widely used additive manufacturing process, where a three dimensional object is fabricated directly from a solid computer model. This thesis develops a projection type SLA (PSLA) test bed using a digital micro mirror device. The goal is to improve the dimensional accuracy and surface quality of the polymer parts through detailed process modeling and gain predictive ability about the duration of the printing process. For that purpose; (i) process parameters of the PSLA system have been analyzed, (ii) material properties of different polymers have been identiffed through experimental techniques, and a curing process model has been established, and (iii) some case studies have been conducted. The information deduced from the system is used to set the continuous movement speed of the vertical axis to obtain "layerless printing" of parts where the surface quality is signiffcantly improved compared to conventional layer-by-layer printing. The results show that the process planning approach used in this thesis can produce highly accurate parts. Experiments on more challenging part designs such as high aspect ratio and micro scale parts have also been conducted, and limits of the three dimensional printing system have been determined.