WAXLESS PRECISION CASTING PROCESS

• US 20110132562A1
• Filed: 12/07/2010
• Published: 06/09/2011
• Est. Priority Date: 12/08/2009
• Status: Abandoned Application

• Current Assignee: Mikro Systems, Inc., Siemens Energy Incorporated (Siemens AG)
• Original Assignee: Mikro Systems, Inc.
• Inventors: Klinger, Jill, Appleby, Michael P., Fraser, Iain A., Paulus, John R., Merrill, Gary B.
• Application Number:
  US12/961,621
• Publication Number:
  US 20110132562A1
• Time in Patent Office: Days
• US Class Current: 164/9
• CPC Class Codes: B22C 7/06 Core boxes
• CPC Class Codes: B22C 9/02 Sand moulds or like moulds for shaped castings
• CPC Class Codes: B22C 9/04 Use of lost patterns
• CPC Class Codes: B22C 9/10 Cores; Manufacture or installation of cores breaker cores B22C9/084
• CPC Class Codes: B22C 9/103 Multipart cores
• CPC Class Codes: B22C 9/22 Moulds for peculiarly-shaped castings
• CPC Class Codes: B22C 9/24 for hollow articles

Abstract

Alloy products are produced with a waxless casting process. A model of a ceramic casting vessel (34) defining a desired product shape is digitally divided into sections (10, 40, 42). Each section is translated into a soft alloy mater tool (14) including precision inserts (20) where needed for fine detail. A flexible mold (24) is cast from each master tool, and a section of the ceramic casting vessel is cast from the respective flexible mold. The vessel sections are assembled by aligning cooperating precision features (58, 60) cast directly into each section and the alloy part is cast therein. No wax or wax pattern tooling is needed to produce the cast alloy product. Engineered surface features (54) may be included on both the interior and exterior surfaces of the shell sections.

Claims

1. A casting process for an alloy component comprising:

casting a ceramic core into a flexible core mold, the flexible core mold defining a geometry of an interior passageway of the alloy component and a first cooperating alignment feature;

casting a ceramic shell in at least two sections into respective flexible shell molds, the flexible shell molds collectively defining an external geometry of the alloy component and a second cooperating alignment feature;

forming a ceramic casting vessel by assembling the ceramic core within the ceramic shell sections while aligning the first and second cooperating alignment features;

casting alloy into the ceramic casting vessel; and

removing the ceramic casting vessel to reveal the alloy component having the interior passageway.

2. The casting process of claim 1, further comprising casting any one of the flexible core mold or flexible shell molds with a process comprising:

forming a master mold to define a first region comprising relatively low precision features;

incorporating a mold insert into the master mold to define a second region comprising relatively high precision features having dimensional tolerances smaller than those of the relatively low precision features; and

casting the any one of the flexible molds into the joined master mold and mold insert.

3. The casting process of claim 1, wherein at least one of the casting steps comprises vibrating the respective flexible mold while introducing a ceramic material slurry into the respective flexible mold, the vibrating step effective to displace air entrapped by a protruding surface of the respective flexible mold with the slurry.

4. The casting process of claim 1, further comprising using a common composition of ceramic material for casting the ceramic core and for casting the ceramic shell sections.

5. The casting process of claim 1, further comprising positioning an active device into at least one of the flexible core molds, flexible shell molds or ceramic shell sections for operation during a subsequent casting step.

6. The casting process of claim 1, further comprising forming the cooperating alignment features along a part line between the shell sections.

7. The casting process of claim 1, further comprising applying an adhesive between the shell sections to at least partially seal a part line there between.

8. The casting process of claim 1, further comprising:

disposing a first of the shell sections on a surface;

assembling the ceramic core onto the first of the shell sections;

visually confirming proper alignment of the ceramic core relative to the first of the shell sections;

then

assembling a second of the shell sections onto the ceramic core and first of the shell sections; and

visually confirming proper alignment of the second of the shell sections relative to the first of the shell sections or to the ceramic core.

9. The casting process of claim 1, further comprising firing the ceramic core and the shell sections to different degrees of a fully sintered condition to control shrinkage and co-sintering of adjoining surfaces prior to a final sintering step, prior to the step of casting alloy into the ceramic casting vessel.

10. The casting process of claim 1, further comprising casting at least one of the flexible shell molds with a process comprising:

forming a master mold;

texturing a surface of the master mold to achieve a desired topography; and

casting the at least one of the flexible shell molds into the master mold to replicate the desired topography;

whereby the desired topography is then replicated through the respective ceramic shell section to a surface of the alloy component.

11. The casting process of claim 10, wherein the step of texturing comprises subjecting the master mold surface to one of grit blasting, sanding, laser-derived pot marking, or additional of a second phase material.

12. The casting process of claim 1, further comprising casting at least one of the flexible shell molds with a process comprising:

forming a master mold;

forming an intermediate mold comprising a fibrous material;

grit blasting a surface of the intermediate mold to achieve a desired topography; and

casting the at least one of the flexible shell molds into the intermediate mold to replicate the desired topography;

whereby the desired topography is then replicated through the respective ceramic shell section to a surface of the alloy component.

13. The casting process of claim 1, further comprising subjecting at least one of the ceramic core or ceramic shell sections to a thermal reshaping process after it has reached a green body state but before it is fully fired.

14. The casting process of claim 1, further comprising forming at least one of the flexible shell molds to define an engineered surface feature on an exterior surface of the respective ceramic shell section.

15. The casting process of claim 1, further comprising during at least one of the casting steps, embedding a reinforcing material into at least one of the ceramic core and ceramic shell sections.

16. The casting process of claim 1, further comprising forming a tab on at least one of the ceramic shell sections and subjecting the tab to a thermal reshaping process after it has reached a green body state but before it is fully fired.

17. The casting process of claim 1, further comprising forming at least one of the ceramic core and the ceramic shell to comprise a portion extending there between when assembled to form the ceramic casting vessel to define a geometry of a cooling passage through the alloy component.

18. The casting process of claim 1, further comprising forming an insert to be disposed between the ceramic core and the ceramic shell when the ceramic casting vessel is assembled to define a geometry of a cooling passage through the alloy component.

19. The casting process of claim 18, further comprising forming the insert to comprises a nonlinear portion defining a nonlinear cooling passage.

20. The casting process of claim 18, further comprising forming the insert to define a plurality of cooling passages.

21. A casting process for an alloy component comprising:

forming master tooling defining each of a plurality of sections of a ceramic casting vessel shape, the sections each comprising at least one alignment feature shaped for cooperative alignment with an alignment feature of another of the sections for assembly of the ceramic casting vessel shape;

casting a plurality of identical sets of flexible molds in the master tooling, each flexible mold replicating a respective section of the ceramic casting vessel shape, the master tooling being reused for casting multiple identical sets of flexible molds;

casting a plurality of sets of identical ceramic casting vessel sections in the plurality of sets of identical flexible molds;

assembling a plurality of identical ceramic casting vessels by assembling the respective plurality of sets of ceramic casting vessel sections while aligning the respective cooperative alignment features;

casting the plurality of identical alloy components in the plurality of identical ceramic casting vessels; and

removing the ceramic casting vessels to reveal the plurality of identical alloy components.

22. The casting process of claim 21, further comprising:

forming the master tooling to comprise a first region comprising relatively low precision features;

incorporating a mold insert into the master tooling to define a second region comprising relatively high precision features having dimensional tolerances smaller than those of the relatively low precision features.

23. The casting process of claim 21, wherein the step of casting a plurality of sets of identical ceramic casting vessel sections comprises vibrating the respective flexible mold while introducing a ceramic material slurry into the respective flexible mold, the vibrating step effective to displace air entrapped by a protruding surface of the respective flexible mold with the slurry.

24. The casting process of claim 21, further comprising positioning an active device into at least one of the flexible molds or ceramic casting vessel sections for operation during a subsequent casting step.

25. The casting process of claim 21, further comprising firing the ceramic shell sections to respective different degrees of a fully sintered condition to control shrinkage and co-sintering of adjoining surfaces prior to a final sintering step and prior to the step of casting the plurality of identical alloy components.

26. The casting process of claim 21, further comprising:

texturing a surface of the master tooling to achieve a desired topography; and

replicating the desired topography into the plurality of identical alloy components through the respective flexible molds and ceramic casting vessels.

27. The casting process of claim 26, wherein the step of texturing comprises subjecting the master tooling surface to one of grit blasting, sanding, laser-derived pot marking, or additional of a second phase material.

28. The casting process of claim 21, further comprising forming the master tooling to define shapes of a core and at least two shell sections including respective alignment features which when assembled together, with respective alignment features in cooperative alignment, form the ceramic casting vessel shape.

29. The casting process of claim 21, further comprising forming a tab on at least one of the ceramic casting vessel sections and subjecting the tab to a thermal reshaping process after it has reached a green body state but before it is fully fired.

31. The casting process of claim 30, further comprising:

using the master tooling to cast a plurality of sets of identical flexible molds for each of the respective vessel sections; and

using the plurality of sets of identical flexible molds to produce in parallel a respective plurality of alloy components in accordance with the steps of claim 28.

30. A casting process for an alloy component comprising:

defining a ceramic casting vessel in a digital model;

dividing the digital model into a plurality of vessel sections comprising cooperating alignment features;

fabricating master tooling representing each of the vessel sections;

casting flexible molds for each of the vessel sections in the master tooling;

casting ceramic casting vessel sections in the flexible molds;

assembling the ceramic casting vessel sections into a ceramic casting vessel while aligning the cooperating alignment features;

casting an alloy component in the ceramic casting vessel; and

removing the ceramic casting vessel to reveal the alloy component.

32. The casting process of claim 30, further comprising:

forming the master tooling to define a first region comprising relatively low precision features;

incorporating a mold insert into the master mold to define a second region comprising relatively high precision features having dimensional tolerances smaller than those of the relatively low precision features.

33. The casting process of claim 30, wherein the step of casting ceramic casting vessel sections comprises vibrating the respective flexible mold while introducing a ceramic material slurry into the respective flexible mold, the vibrating step effective to displace air entrapped by a protruding surface of the respective flexible mold with the slurry.

34. The casting process of claim 30, further comprising positioning an active device into at least one of the flexible molds or ceramic casting vessel sections for operation during a subsequent casting step.

35. The casting process of claim 30, further comprising firing the ceramic shell sections to respective different degrees of a fully sintered condition to control shrinkage and co-sintering of adjoining surfaces prior to a final sintering step and prior to the step of casting the alloy component.

36. The casting process of claim 30, further comprising:

texturing a surface of the master tooling to achieve a desired topography; and

replicating the desired topography into the alloy component through the respective flexible mold and ceramic casting vessel.

37. The casting process of claim 30, wherein the step of texturing comprises subjecting the master tooling surface to one of grit blasting, sanding, laser-derived pot marking, or additional of a second phase material.

38. The casting process of claim 30, further comprising:

forming the master tooling to define shapes of a core and at least two shell sections including respective alignment features which when assembled together, with the respective alignment features in cooperative alignment, form the ceramic casting vessel shape.

39. The casting process of claim 30, further comprising forming a tab on at least one of the ceramic casting vessel sections and subjecting the tab to a thermal reshaping process after it has reached a green body state but before it is fully fired.

40. The casting process of claim 30, further comprising:

forming an intermediate mold comprising a fibrous material from the master tooling;

grit blasting a surface of the intermediate mold to achieve a desired topography; and

casting at least one of the flexible molds into the intermediate mold to replicate the desired topography;

whereby the desired topography is then replicated into a surface of the alloy component.

41. The casting process of claim 30, further comprising subjecting at least one of the ceramic casting vessel sections to a thermal reshaping process after it has reached a green body state but before it is fully fired.

42. The casting process of claim 30, further comprising forming the master tooling to define an engineered feature on an exterior surface of the ceramic casting vessel.

43. The casting process of claim 30, further comprising embedding a reinforcing material into at least one of the ceramic casting vessel sections.