Blade Platform Assembly via Metal Powder Injection and Sintering
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Solution Overview
Problem
The existing manufacturing processes for bladed wheel sectors in turbine engines, such as lost-wax casting and mechanical-brazed assembly, are costly, complex, and inefficient due to the need for multiple steps and difficult machining of closely spaced blades, and metal powder injection molding (MIM) is not suitable for large parts.
Innovation Solution
A method where blades are manufactured separately and precisely positioned within a metal powder platform blank before sintering, allowing for a single operation assembly that eliminates the need for additional connection steps and reduces costs by leveraging the advantages of MIM while overcoming its limitations for large parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lost-wax casting process is used to manufacture stator sector, then the platform sectors and blades can be formed in a single operation, but additional machining and polishing steps are required to correct manufacturing defects, increasing cost and complexity
Solution Approach 1:
The invention changes the key parameter of manufacturing precision by using investment casting with precision control, achieving surface accuracy and dimensional tolerance that eliminates the need for subsequent machining and polishing operations. This parameter change in precision control transforms the process from one requiring corrective machining to one that is finish-casting ready.
2Shape
If blades are positioned closely together in the platform, then the stator sector achieves compact design, but machining operations become difficult to implement due to limited tool access
Solution Approach 1:
The invention replaces mechanical machining operations with precision investment casting that directly forms the compact platform-blade assembly. The casting process uses a mold that accommodates the compact arrangement of blades, eliminating the need for mechanical tool access to tightly spaced features and resolving the manufacturing difficulty while preserving the compact design.
3Strength
If mechanical-brazed assembly process is used to connect blades and platforms, then the components can be assembled with good connection strength, but the process becomes long and complex
Solution Approach 1:
The invention merges the blade and platform components into a single integrated casting operation. Instead of separately manufacturing components and then brazing them together through a complex multi-step assembly process, the investment casting method forms the complete assembly with blades mounted in platforms in one operation, eliminating the brazing step while maintaining structural integrity through the monolithic casting.
4Ease of manufacture
If MIM process is used to manufacture large metal parts like stator sectors, then cost reduction and mechanical properties comparable to forging can be achieved, but the process is not suitable for large parts due to shrinkage and density issues
Solution Approach 1:
The invention uses a disposable wax pattern in the investment casting process that is deliberately designed to be imperfect and is completely removed during the dewaxing step. This disposable pattern allows for easy accommodation of large part geometries without the shrinkage and density constraints of MIM, as the wax is entirely eliminated and replaced by molten metal that fills the cavity directly, achieving both cost-effectiveness and dimensional accuracy for large parts.
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 method enables precise and durable assembly of blades within platforms, reducing manufacturing time and costs by allowing for precise positioning and sintering of blades and platforms in a single operation, resulting in a stator sector with a homogeneous density and sealed connections without additional retouching.
Implementation Method 1
sintering of the metal powder
Data Source
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AI summary
The invention relates to a method for manufacturing an assembly (11) including a plurality of blades (9) mounted in a platform (7, 8), wherein: the blades (9) are manufactured separately from the platform (7, 8), the blades (9) being finished after manufacturing; a mixture of metal powder and thermoplastic binder is prepared; the mixture is injected into a mould to obtain a platform blank (7, 8); an operation is performed to remove the binder from the platform blank (7, 8) prior to assembling the finished blades (9) to said blank (7, 8); one end of the finished blades (9) is inserted into a recess provided in the platform blank (7, 8) in order to assemble the assembly (11); and the assembly of the platform blank (7, 8) with the finished blades (9) is sintered to combine the assembly (11).