[1] Part design and geometry directly affect the castability, with volume, surface area and the number of features being the most important attributes.
If the design has undercuts or interior cavities it decreases castability due to tooling complexity.
[1] Sudden changes in wall thickness reduce castability because it induces turbulence during filling; fillets should be added to avoid this.
[2] However, the casting process can be very economical for part designs that require intricate contoured surfaces, thickness variations, and internal features.
Material properties that influence their castability include their pouring temperature, fluidity, solidification shrinkage, and slag/dross formation tendencies.