Cooled turbine blade cast tip recess

A method of manufacturing an air-cooled turbine blade having an outer surface, side walls and a tip wall, the side walls having tip edges, the tip wall extending between the side walls and recessed a predetermined distance from the tip edges to form a tip recess, the tip wall having a bottom surface and a top surface, the top surface defining a portion of the tip recess, the method comprising the steps of:

• forming a ceramic mold around cores consisting of a first core and a second core that are adjacent and not coupled to one another, the ceramic mold having an inner surface shaped to complement at least a portion of the turbine blade outer surface and defining a cavity, the first and second cores disposed in the cavity, the first core having an outer surface shaped to complement the tip wall bottom surface, the second core having a tip surface, a side surface, and a protrusion, the tip surface shaped to complement at least a portion of the tip wall top surface and disposed proximate the first core outer surface, the side surface shaped to complement at least a portion of the side wall, and the protrusion extending from the second core side surface to contact at least a portion of the ceramic mold inner surface and comprising a platinum pin;
• injecting metal into the ceramic mold cavity to at least partially cover the first and second cores to melt the platinum pin and incorporate the platinum pin into the metal;
• separating a first portion of the second core and ceramic mold surrounding the first portion of the second core from a second portion of the second core, the first portion of the second core including an area located inwardly from the protrusion and a first portion of the side surface of the second core, the second portion of the second core including the tip surface of the second core and a second portion of the side surface adjacent the tip surface;
• and
• removing the second portion of the second core and the ceramic mold from the metal to expose the tip recess and the blade, and wherein the platinum pin of the projection remains incorporated in the blade.