Turbine Shroud Segment Cooling Passages via Powder Injection Molding
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Solution Overview
Problem
The manufacturing of turbine shroud segments with cooling holes and passages using electric discharge machining (EDM) is costly and limited by geometry accessibility, leading to inefficiencies in the process.
Innovation Solution
The method involves separately molding first and second parts by powder injection molding to define arcuate outer and inner portions with complementary surfaces and grooves, interconnecting them to create cooling passages in a green state, and then debinding and sintering to fuse the parts, forming a shroud segment with integrated cooling passages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electric discharge machining (EDM) is used to create cooling holes and passages after the shroud segment is formed, then cooling features can be added to the turbine shroud segment, but manufacturing costs increase and the process is limited by geometry accessibility
Solution Approach 1:
The cooling passages and holes are formed during the powder injection molding process itself, before the final sintering step. The green state parts are molded with integrated cooling features, eliminating the need for subsequent EDM operations. This preliminary formation of cooling structures resolves the contradiction by achieving cooling effectiveness without the high costs and accessibility limitations of post-processing EDM.
Solution Approach 2:
The manufacturing process merges the formation of the shroud segment structure and the cooling passages into a single powder injection molding operation. Both the external geometry and internal cooling features are created simultaneously in the green state, then finalized through sintering. This consolidation eliminates separate EDM operations, reducing manufacturing costs while maintaining cooling effectiveness.
2Reliability
If cooling holes and passages are created using EDM operations after the shroud segment is formed, then the shroud segment can be manufactured, but the manufacturing process becomes complex and time-consuming
Solution Approach 1:
The process merges structure formation and cooling feature creation into a single powder injection molding step. The green state parts are molded with both external geometry and internal cooling passages integrated, then sintered together in one operation. This eliminates the need for separate EDM operations, significantly reducing manufacturing process complexity while maintaining structural integrity.
Solution Approach 2:
Cooling passages are formed in advance during the green state molding process, before final sintering. This preliminary formation integrates cooling features into the manufacturing flow rather than adding them as a separate post-processing step, reducing overall process complexity while ensuring structural integrity through the sintering operation.
3Reliability
If traditional EDM processes are used to create cooling features, then cooling passages can be formed, but productivity decreases due to the sequential nature of the operations
Solution Approach 1:
The formation of cooling passages is merged with the main shroud segment manufacturing process. Both are created in the same powder injection molding operation and finalized together through sintering. This eliminates sequential operations, significantly improving manufacturing efficiency while ensuring cooling functionality is properly integrated into the final product.
Solution Approach 2:
Cooling passages are formed in advance during green state molding, allowing them to be created simultaneously with the shroud segment structure rather than sequentially afterward. This preliminary formation, followed by single-step sintering, dramatically improves productivity while maintaining reliable cooling functionality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces manufacturing costs and enhances accessibility by efficiently integrating cooling passages within the shroud segment, improving cooling efficiency and reducing the limitations of EDM processes.
Implementation Method 1
separately molding at least first and second parts by powder injection molding
Implementation Method 2
debinding and sintering the interconnected parts to fuse the parts
Data Source
AI summary
A method of manufacturing a shroud segment, including separately molding at least first and second parts by powder injection molding. The first part has an inner surface and at least one fluid passage in communication with the inner surface. The second part has an outer surface complementary to the inner surface of the first part. At least one of the inner and outer surfaces is formed to define a plurality of grooves. A plurality of cooling passages in fluid communication with the at least one fluid passage are defined with the plurality of grooves by interconnecting the inner and outer surfaces while the first and second parts remain in a green state. The interconnected parts are debound and sintered to fuse the parts to define at least a portion of the shroud segment including the cooling passages.