Method for forming a wax model for a turbine blade

A method for forming a wax model for the manufacture of turbine blades by lost-wax casting, wherein

• a core is provided, defining ducts extending between a root and a tip,
• a lower surface shell and an upper surface shell are provided,
• the lower surface shell and the upper surface shell are positioned on either side of the ducts of the core adjacent to the root,
• the lower surface shell and the upper surface shell are bonded around the core,
• the core equipped with the lower surface shell and with the upper surface shell is positioned in an injection mold,
• wax is injected around said core equipped with the lower surface shell and with the upper surface shell, so as to form a wax model comprising a blade airfoil and a blade root comprising a fir tree, the lower surface shell and the upper surface shell being positioned around the core so as to form a portion of the fir tree of the wax model.