Fan shaft casting design: simulation verification and trial casting evaluation

Abstract

A fan shaft casting design intended for high-temperature service was developed and evaluated through simulation and trial casting. Initial casting simulations using NovaFlow&Solid were conducted to identify an optimal gating and riser design for sand-casting process. A rectangular tapered sprue (52 mm × 26 mm entrance area, taper angle 1°) was employed for manufacturability and to stabilize gravity filling. Melt entry was controlled using a Weir-type pour basin (depth 100mm, Weir radius 2.5mnm) coupled with an offset dross-trap to reduce turbulence and surface oxidation. Continuous tangential gating (length 667.5 mm, thickness 12 mm, width 150 mm, 5° taper) induced a controlled vortex fill, promoting non-turbulent filling behavior while maintaining thermal segregation of hotter metal toward the top of the shaft along the gate length. Directional solidification was supported by a ~1° bottom-shaft taper and adding an exothermic sleeve feeder above the blade-shaft junction. Among four exothermic feeder sleeves evaluated simulated, the optimal riser was an exothermic sleeve (internal volume: 577,267.65 mm³) with a 70 mm neck diameter, providing 17% utilization while eliminating shrinkage porosity at the blade root. The resulting design parameters were then applied to a no-bake molding system, where the final fan shaft was cast using SCH 15 stainless steel. The cast fan shaft was assessed through inspections, followed by sectioning to evaluate internal soundness. The casting trial results showed with most sections free from shrinkage cavities and exhibiting only minimal surface depressions. The observed deviation between the simulated and experimental casting results arises from the software’s limited material database, which lacked the specific alloy employed in the actual casting trials, and also by several additional factors inherent to real casting conditions which were assumed constant during simulation. However, the final casting output demonstrated fair agreement with the simulation results which confirms the effectiveness of the molding system and the adequacy of the developed casting design for producing a sound fan shaft component.