A process for manufacturing a plurality of single-crystal nozzle sectors each including at least a first blade extending between two platforms by lost-wax casting, includes casting a molten metal into a plurality of ceramic molds distributed in a cluster about an axis, and directional solidification of the cast metal in a furnace comprising a radiant heating element configured to be arranged around the cluster, a solidification front of the metal advancing in each mold in a direction parallel to the cluster axis during directional solidification. Each mold of a second shell separate from a first molding shell of the nozzle sector, which delimits a second cavity for molding a dummy blade acting as a heat shield.