Parameter Optimization and Precision Control of Water-Soluble Support Cores for Hollow Composite Castings Fabricated by Slurry Microextrusion Direct Forming Method

The optimization of slurry content and forming process parameters has a significant effect in slurry microextrusion direct forming method. In this article, magnesium sulfate monohydrate (MgSO₄) and polyvinylpyrrolidone (PVP) were used as raw materials to prepare the slurry, and the component ratios of the slurry and the optimization of its forming process were discussed. The optimum slurry content is 64 wt.% by mass of magnesium sulfate monohydrate and 36 wt.% by mass of binder consisting of PVP-EtOH. The process parameters that include printing speed, extrusion pressure, and the ratio of printing layer height to extrusion diameter were selected as influencing factors. The orthogonal experiment results show that a printing speed of 850 mm/min, an extrusion pressure of 250 kPa, and a layer height of 510 μm of the extrusion diameter are the optimized process parameters. Under the optimized printing parameters, the surface roughness of the prepared samples is 23.764 μm, with dimensional deviations of 0.71%, 0.77%, and 2.56% in the X, Y, and Z directions, respectively.