Process for the manufacture by lost wax moulding of parts that include at least one cavity

1. A process for the manufacture by lost wax moulding of a part that includes at least one cavity, comprising,

forming a core in a ceramic material to reproduce said cavity,

inserting the core into in a wax mould,

placing at least one element on the core thereby forming a spacer between the core and an internal wall of the wax mould,

forming a wax model of the part with the core by injecting wax into the mould,

forming a shell mould in ceramic material from the wax model,

removing the wax,

pouring casting metal into the shell mould, and

dissolving said at least one element with the casting metal during said pouring of said casting metal,

wherein said dissolving of said at least one element is performed such that an outer surface of said part is free of protuberances at a location where said at least one element was placed, and

wherein the element is of elongated form and placed on the core in a laying position such that the element is flush with an outer surface of the wax model formed by injecting wax into the mould.

2. A process according to claim 1 , further comprising:

forming a cavity in a wall of the core, and

placing said element forming said spacer into said cavity in the wall of the core.

3. A process according to claim 1 , wherein the element is in the form of a rod with a circular section.

4. A process according to claim 1 , wherein the element is in the form of a rod with a polygonal section.

5. A process according to claim 2 , wherein the core includes notches forming disrupters of fluid flow in the part, and said placing of said at least one element on the core comprises inserting said at least one element into one of said notches.

6. A process according to claim 2 , wherein the core includes notches forming disrupters of fluid flow in the part, and said placing of said at least one element on the core comprises placing said at least one element in a direction parallel to the notches.

7. A process according to claim 2 , wherein the core includes notches forming disrupters of fluid flow in the part, and said placing of said at least one element on the core comprises placing said at least one element so as to form an angle with respect to said notches.

8. A process according to claim 1 , wherein the part is a turbine blade, and said placing of at least one element on the core comprises placing at least one element on a side of a lower surface of said core and placing at least one element on a side of an upper surface of said core.

9. A process according to claim 2 , wherein said forming of said cavity in the wall of the core is performed at a same time as said forming of said core.

10. A process according to claim 4 , wherein said element is in the form of a rod with a square section.

11. A process according to claim 4 , wherein said element is in the form of a rod with a rectangular section.

12. A process according to claim 4 , wherein said element is in the form of a rod with a hexagonal section.

13. A process according to claim 7 , wherein said angle is a right angle.

14. A process according to claim 1 , wherein said dissolving of said at least one element is performed such that an inner surface of said part has a protuberance at a location where said at least one element was placed.

15. A process according to claim 1 , wherein said method is free of any step of grinding a surface of said part at a location where said at least one element was placed.

16. A process according to claim 1 , wherein said at least one element is made of platinum.

17. A process according to claim 1 , wherein said placing of said at least one element on the core comprises gluing said at least one element on a wall of the core.