Turbine Airfoil Tip Rebuild Using Ceramic Core Witness Features
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Solution Overview
Problem
Current methods for manufacturing and repairing turbine blades and vanes are time-consuming and costly, especially for the tips, which are prone to damage and require expensive replacements, and often necessitate the use of new materials, whereas existing materials in airfoil manufacturing facilities are not fully utilized.
Innovation Solution
A method involving the use of a ceramic casting mold with a ceramic core and shell that serves as a support structure for additive manufacturing, allowing for the deposition and fusion of metallic powder to form blade tips, utilizing existing materials and reducing material waste, and enabling the repair of damaged tips by re-forming the ceramic core and shell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional casting methods are used to manufacture turbine blades, then the blades can be produced with complex internal cooling passages, but the manufacturing process is time-consuming and costly
Solution Approach 1:
The ceramic core is pre-formed with witness features and internal cavities that define the cooling passages before the casting process. This preliminary preparation of the mold structure eliminates the need for time-consuming post-casting machining and allows for faster production of blades with complex internal geometries
Solution Approach 2:
A ceramic core is introduced as an intermediary object within the mold cavity to define the internal cooling passages. The core is surrounded by molten metal but remains separate, allowing the metal to solidify around it. After casting, the ceramic core is removed, leaving the desired internal passages without requiring additional machining time
2Manufacturing precision
If ceramic cores are used to form cooling passages, then complex internal geometries can be achieved, but the cores must be removed requiring additional processing steps
Solution Approach 1:
The ceramic core is designed with self-removing features including witness markers that indicate when the core has been completely extracted. The core structure itself serves as the pattern for the cooling passages, and its removal automatically creates the desired geometry without requiring additional tooling or complex extraction mechanisms
Solution Approach 2:
The ceramic core is designed as a disposable sacrificial element that is removed after serving its purpose of defining the internal passages. Using inexpensive ceramic material that can be easily broken down or dissolved eliminates the need for complex core extraction mechanisms and allows for simple, cost-effective mold design
3Ease of repair
If blade tips are damaged, then replacements are needed, but replacement tips require new materials and are expensive
Solution Approach 1:
Instead of discarding the entire blade when the tip is damaged, the method recovers and reuses the existing blade body and ceramic core. The damaged tip is removed and a new tip is formed by additive manufacturing using the existing ceramic core as the mold, thereby recovering most of the original material and avoiding the need to manufacture a completely new blade
Solution Approach 2:
The repair process changes the state of the tip from damaged to restored by adding new material through additive manufacturing. The ceramic core remains in the same state and is reused, while the metal tip is completely replaced layer-by-layer, transforming the damaged component into a like-new condition without wasting the original blade structure
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 is cost-effective and time-efficient, utilizing existing materials to manufacture and repair turbine components with precise control over microstructure and minimizing material waste, while maintaining the high performance required for gas turbine engines.
Implementation Method 1
irradiating at least a portion of the metallic powder to form a fused layer
Implementation Method 2
irradiating at least a portion of the metallic powder to form a fused layer
Implementation Method 3
A method involving the use of a ceramic casting mold with a ceramic core and shell that serves as a support structure for additive manufacturing
Implementation Method 4
pouring a liquid metal into a ceramic casting mold to form a cast component upon solidification of the liquid metal
Implementation Method 5
depositing a layer of metallic powder onto the surface portions
Data Source
AI summary
Methods of manufacturing or repairing a turbine blade or vane are described. The airfoil portions of these turbine components are typically manufactured by casting in a ceramic mold, and a surface made up of the cast airfoil and at the least the ceramic core serves as a build surface for a subsequent process of additively manufacturing the tip portions. The build surface is created by removing a top portion of the airfoil and the core, or by placing an ultra-thin shim on top of the airfoil and the core. The overhang projected by the shim is subsequently removed. These methods are not limited to turbine engine applications, but can be applied to any metallic object that can benefit from casting and additive manufacturing processes. The present disclosure also relates to finished and intermediate products prepared by these methods.