Studies in direct tooling using stereolithography

Rapid prototyping (RP) technologies are valuable for reducing product devel opment cycle times by creating physical models for visual inspection and fo rm-fit studies directly from a 3-D database. However, if the part is meant for volume production, tooling will be necessary. Tool development and fabr ication using conventional techniques and materials is time consuming and e xpensive. Therefore. it is risky to commit to production tooling in the ini tial stages of product development. Low volume prototyping is highly desira ble bur requires a small number of parts (hundreds) to be produced quickly and economically. To meet this need, this paper studies direct tooling usin g the RP technology of stereolithography (SL) to produce photopolymer tools . Without modifications to improve thermal response, SL molds will not be a ble to produce production-quality parts. This experimental study quantifies the thermal characteristics of an SL mold for a simple parr geometry. Seve ral modifications that affect thermal properties are then studied and both thermal response and part quality are quantified. The data indicate that al though it is possible to change the thermal response of an SL mold and obta in reasonable parts, the ability to duplicate traditional mold characterist ics land thus simulate part production before committing to high-volume too ling) is probably not practical. Similar results were achieved when using a more realistic final-part geometry on a production mold machine. Although mold process simulation using SL molds could provide useful design guidance for traditional high-volume part production, this work suggests that these SL molds can be used for low-volume parr production. By reducing mold fabr ication time and costs, low-volume part production could become cost-effect ive using traditional high-volume manufacturing techniques.