Lost foam and sand cores stage manufacturing technology

A method of casting a workpiece having at least one cavity therein, comprising:

• (a) preforming a core of bonded granular material in the desired configuration of the cavity of the workpiece, the core having oppositely facing first and second surfaces with at least one core cavity extending between the first and second surfaces, said core cavity having exposed sides at the first and second surfaces and being in the desired configuration of a wall for the workpiece;
• (b) preforming a first foam fusible member of fusible material, then positioning the first foam fusible member on the first surface of the core, overlying and closing off one of the exposed sides of said core cavity;
• (c) preforming a second foam fusible member of fusible material, then positioning the second foam fusible member on the second surface of the core, overlying and closing off an opposite one of the exposed sides of said core cavity, forming an assembly of the first and second foam molds with the core, leaving said core cavity unfilled;
• (d) placing the assembly in a refractory mold cavity and packing granular refractory material around the assembly;
• (e) delivering molten metal into the mold cavity into contact with the first and second foam fusible members, which decompose, causing the molten metal to flow into said core cavity, forming a metal wall for the workpiece in said core cavity and in the spaces previously occupied by the foam fusible members;
• then
• (f) removing the workpiece and the core from the mold cavity and removing the bonded granular material of the core from the workpiece, providing the desired cavity for the workpiece.

A method of casting a centrifugal pump stage component having a plurality of a plurality of passages extending outward from a central axis, each of the passages being defined by sidewalls and first and second oppositely facing walls, the method comprising:

• (a) forming a core of bonded granular material, having outward extending fingers separated by core cavities, each of the fingers being in the configuration of one of the passages of the component, and each of said core cavities being in the configuration of one of the sidewalls of the component, said core cavities having first and second exposed sides;
• (b) preforming a first foam fusible member of fusible material, then positioning the first foam fusible member on a first surface of the core in contact with the fingers, overlying and closing off the first exposed sides of said core cavities, the first foam fusible member having portions in the configuration of the first walls of the passages of the component;
• (c) preforming a second foam fusible member of fusible material, then positioning the second foam fusible member on a second surface of the core in contact with the fingers, overlying and closing off the second exposed sides of said core cavities, the second foam fusible member having portions in the configuration of the second walls of the passages of the component, the foam fusible members and the core forming an assembly, leaving said core cavities unfilled;
• (d) placing the assembly in a refractory mold cavity and packing granular refractory material around the assembly;
• (e) delivering molten metal into the mold cavity into contact with the first and second foam fusible members, which decompose, causing the molten metal to flow into said core cavities, forming sidewalls for the passages of the component in said core cavities and forming first and second walls for the passages in the spaces previously occupied by the foam fusible members;
• then
• (f) removing the component and the core from the mold cavity and removing the bonded granular material of the core from the component, providing the desired passages for the component.