Multi-piece mandrel for CMC components

1. A mandrel for a molding process, the mandrel comprising:

a first portion having a first draft surface and a second draft surface;

a second portion and a third portion, the second portion having a third draft surface and the third portion having a fourth draft surface wherein the first draft surface engages the third draft surface and the second draft surface engages the fourth draft surface;

a channel extends along a length of the mandrel at an interface between the first, second, and third portions such that the second portion does not contact the third portion; and

wherein the first portion has a generally rhombus cross-section, the second and third portions each have a generally triangular cross-section, and the mandrel forms a substantially triangular cross-section.

2. The mandrel of claim 1 , wherein the first and second draft surfaces provide a taper along a length of the first portion.

3. The mandrel of claim 2 , wherein the third draft surface provides an opposing taper along a length of the second portion.

4. The mandrel of claim 1 , wherein the mandrel has a constant cross-section along a length of the mandrel.

5. The mandrel of claim 1 , wherein a plurality of channels extend along a length of the mandrel.

6. The mandrel of claim 5 , wherein one of the channels is near each corner of the triangular cross-section.

7. The mandrel of claim 1 , wherein a hole is arranged in the first portion and extends along a length of the first portion.

8. The mandrel of claim 1 , wherein the first, second, and third portions are formed from graphite.

9. A mandrel for a molding process, the mandrel comprising:

a first portion having a first draft surface and a second draft surface;

a second portion and a third portion, the second portion having a third draft surface and the third portion having a fourth draft surface wherein the first draft surface engages the third draft surface and the second draft surface engages the fourth draft surface; a channel extends along a length of the mandrel at an interface between the first, second, and third portions such that the second portion does not contact the third portion; and

wherein at least three channels extend along the length of the mandrel.

10. The mandrel of claim 9 , wherein the first portion has a generally rhombus cross-section, the second and third portions each have a generally triangular cross-section, and the mandrel forms a substantially triangular cross-section.

11. A mandrel assembly, comprising:

a mandrel, the mandrel formed from a first portion having first and second draft surfaces, a second portion having a third draft surface, and a third portion having a fourth draft surface, wherein the first draft surface engages the third draft surface and the second draft surface engages the fourth draft surface;

a first end piece and a second end piece arranged at opposite ends of the mandrel and configured to secure the first, second, and third portions together; and

wherein the first portion has a generally rhombus cross-section, the second and third portions each have a generally triangular cross-section, and the mandrel forms a substantially triangular cross-section.

12. The mandrel assembly of claim 11 , wherein a pin extends from the first end piece through a hole in the mandrel to the second end piece.

13. The mandrel assembly of claim 11 , wherein the mandrel is formed from graphite.

14. The mandrel assembly of claim 13 , wherein the first and second end pieces are formed from aluminium.

15. The mandrel assembly of claim 11 , wherein a plurality of channels extend along a length of the mandrel, and the each of the channels is formed along adjacent corners of two or more of the respective first, second and third portions.

16. A method of forming a matrix composite component, comprising:

providing a mandrel formed from a first portion, a second portion, and a third portion, the mandrel having a channel that extends along a length of the mandrel at an interface between the first, second, and third portions such that the second portion does not contact the third portion, wherein the first portion has a generally rhombus cross-section, the second and third portions each have a generally triangular cross-section, and the mandrel forms a substantially triangular cross-section; wrapping a matrix composite laminate about the mandrel to form a preform;

densifying the preform;

removing the first portion from the preform; and

removing the second and third portions from the preform after the first portion has been removed.

17. The method of claim 16 , wherein the mandrel has a plurality of channels and the preform is densified via chemical vapor infiltration.

18. The method of claim 16 , wherein the mandrel is mounted within a tooling assembly, the tooling assembly comprising a bottom piece and a top piece that form an outer mold surface for a component.

19. The method of claim 16 , wherein the preform is machined after removing the mandrel to form a plurality of components.