Theoretical and experimental research on the coating process of ceramic stereolithography

Abstract

The coating process in ceramic stereolithography is one of the principal sources of inaccuracy in the height dimension. The coating in stereolithography is a layer-by-layer build-up process, so the thickness of one layer coated is influenced by the previous layer and affects the thickness of the next layer. If inconsistent layer thicknesses exist, they will result in the poor quality of the final product. This paper analyzes the coating process of the slurry-separated system based on a simple 2D model and Navier-Stokes equations, presenting the theoretical equations of layer thickness for the commonly used blade types. Given the characteristics of layer-by-layer coating in stereolithography, the theoretical equations should be constantly iterated to obtain the thickness of each layer. This paper discovers the initial blade gap has a significant impact on the layer thicknesses by theoretical analyses. With the verification of experiments, the results shows that the presence of the unreasonable initial blade gap may lead to large fluctuations in layer thicknesses of the first few layers, and the coating in stereolithography is a "self-regulating"process with a tendency to the desired thickness. The larger the desired layer thickness, the worse this "self-regulating ability"is. This paper defines a coefficient of blade gap and proposes that using the coefficient of blade gap to determine a reasonable initial blade gap based on different working conditions can effectively control the consistency of each layer thickness.