Process Errors and Aspects for Higher Resolution in Conventional Stereolithography

Due to the rapid development of precision manufacturing technologies, there is a growing market need for appropriate rapid prototyping methods with higher resolution. This paper presents aspects for a general optimization of stereolithography accuracy and gives a deeper analysis of important process errors. Beside a higher precision due to improved optical components, it can be shown that for a better vertical resolution one must mainly reduce the penetration depth of the photopolymer. We found that this is also possible with conventional stereolithography materials by using a different wavelength, achieving cured rugged layers with a thickness of 20 micrometer. The major accuracy aspect lies in the understanding of the layer deposition process. A CFD (computational fluid dynamics) study helps to describe important phenomena of blade based coating techniques. As a result, the inaccuracy of the layer deposition is the general limiting factor in stereolithography. This knowledge can be directly applied to commercial stereolithography systems helping users to achieve higher process accuracy.