How do you design an effective gating system for sand casting?

Effective gating system design includes: Pouring basin (controls metal entry, prevents dross), Sprue (vertical channel, tapered to prevent aspiration), Sprue base well (reduces turbulence), Runners (horizontal channels distributing metal), Ingates (connect runners to mold cavity), Risers (feed shrinkage, blind or open), and Chills (control solidification direction). Design principles: Fill mold quickly but avoid turbulence, achieve directional solidification toward risers, filter slag/dross, minimize metal velocity at gates (<0.5 m/s). Simulation software (MAGMA, ProCAST) validates designs before production.