A segregation model study of suspension-based additive manufacturing

The additive manufacturing method of direct ceramic stereolithography directly fabricate complex core and shell molds while suspensions of coarser or denser particles have undergone differential sedimentation and cause particle size segregation. In order to safely use refractory coarse ceramic powder without the segregation problem, we develop a segregation model derived from the degree of segregation parameter (β) with the relation of two time constants; the writing time and the settling time. Given the relationships of material, apparatus, and design parameters, no segregation is expected in the silica particle dispersed suspension with average particle size of 40 μm when laser powers larger than 89 mW or 60 mW is applied to build layers with layer thicknesses of 150 μm or 250 μm, respectively. The explanation and application of the segregation model provided in this article enables to easily determine optimum variables and maximize the efficiency of additive manufacturing methods, thus able to suppress segregation in a layer.