Direct Ink Writing (DIW) & Ceramic Robocasting Vector CAM Prepress Guide

Advanced ceramic additive manufacturing guide for robocasting, woodpile lattice design, spanning filament stability, and Eulerian vector toolpaths.

1. Rheology & Extrusion Mechanics of Direct Ink Writing

Direct Ink Writing (DIW) / Robocasting is a pioneering additive manufacturing method for advanced technical ceramics (Alumina, Zirconia, Hydroxyapatite, Silicon Carbide) without requiring polymer binders or high laser temperatures. By formulating high-solids colloidal suspensions with reversible shear-thinning viscoelastic gels, pastes extrude smoothly through sub-millimeter nozzles and immediately solidify to maintain complex 3D woodpile lattices.

2. CAM Toolpathing & Sintering Shrinkage Pre-Scaling Rules

Vector prepress for ceramic DIW requires strict path continuousness and volumetric compensation:

• Sintering Expansion Scale: Pre-scale all CAD vectors by $S_{\text{scale}} = \frac{1}{1 - S_{\text{shrink}}}$ (typically $1.20\text{--}1.25\times$ for $17\% - 20\%$ densification shrinkage).
• Continuous Serpentine Infill: Generate continuous space-filling Eulerian toolpaths that eliminate stop/start retraction points where pressure fluctuations cause filament thinning or blobbing.
• Spanning Strut Deflection Control: Constrain unsupported spanning gaps $L_{\text{span}} \le 2.5\text{ mm}$ to guarantee $< 15\,\mu\text{m}$ green filament sagging.