Fig. 1. Integral hydraulic multi-way valve structure. (a) External structure of the casting; (b) internal oil channel structure

Fig. 2. Comparison of casting defects. (a)(c) Normal casting; (b) main valve hole fracture and bending; (d) blind hole missing

Fig. 3. Casting system. (a) Composite casting system; (b) schematic of internal gate distribution

Fig. 4. Design of exhaust system. (a) Exhaust design for internal sand core; (b) exhaust design for external mold

Fig. 5. Core structure

Fig. 6. Sand core image

Fig. 7. Single-layer metal liquid flow rate. (a) 3.8 s; (b) 17.4 s

Fig. 8. Double-layer metal liquid flow rate. (a) 3.8 s; (b) 17.4 s

Fig. 9. Nodes flow rate. (a) Flow rate at lower section node (X=15, Y=28, Z=0); (b) flow rate at upper section node (X=28, Y=2, Z=8)

Fig. 10. Integral hydraulic multi-way valve casting. (a) External; (b) internal

Fig. 11. Internal defect inspection

Fig. 12. Internal hardness testing