CMC Cooling Passage Formation Without Fiber-Cutting Machining
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ceramic matrix composite (CMC) components cannot be effectively machined using Electron Discharge Machining (EDM) due to their inability to carry current, leading to weakened structures and exposure to environmental attacks when conventional machining methods are used, which is a challenge in creating internal cooling passages for high-temperature applications.
Innovation Solution
A method involving the use of a hollow member and rod to form cooling passages by embedding and wrapping ceramic matrix composite material around a core, followed by removal of the core and hollow member, ensuring the integrity of the CMC material is maintained without cutting fibers, using materials like nylon or metal alloys that can be easily removed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional machining methods are used to create cooling passages in CMC components, then cooling passages can be formed, but the CMC material structure is damaged with cut fibers and exposed surfaces
Solution Approach 1:
The invention extracts the harmful machining process entirely by using a mandrel that is burned out to create the cooling passage cavity. Instead of cutting or drilling through the CMC material, a removable mandrel is embedded, the CMC is formed around it, then the mandrel is removed by burning out, leaving a clean cavity without cutting the ceramic fibers.
Solution Approach 2:
The mandrel serves as an intermediary object that temporarily occupies the space where the cooling passage will eventually be. It is embedded in the CMC precursor, allows the CMC to form around it, and is subsequently removed by burning out, leaving the desired cooling passage cavity without ever cutting the CMC material.
2Manufacturing precision
If EDM is used to machine cooling passages, then precise passages can be created, but CMC material cannot carry current making EDM ineffective
Solution Approach 1:
The invention replaces the electrical EDM machining system with a mechanical/embedded mandrel approach. Instead of using electrical discharge to erode the material, a physical mandrel is embedded and then removed by burning out, achieving precise passage formation without relying on the CMC's electrical properties.
Solution Approach 2:
The invention changes the fundamental parameter of how the passage is formed - from electrical erosion (EDM) or mechanical cutting (drilling) to thermal removal of a mandrel. The mandrel is made of a material that can be selectively burned out at temperatures below the CMC's degradation point, creating the passage through parameter-based material removal rather than force or electricity.
3Length of moving object
If laser drilling is used for cooling passages, then short passages can be created, but long passages cannot be effectively formed
Solution Approach 1:
The mandrel is embedded in the CMC precursor material before the CMC is formed and cured. This preliminary placement ensures the mandrel is perfectly positioned and supported throughout the entire CMC structure, allowing long passages to be formed without the limitations of post-formed drilling methods like laser drilling.
Solution Approach 2:
The invention transitions from forming passages by removing material from the outside (drilling, laser drilling) to forming passages by having a mandrel define the passage space from within during the CMC formation process. This dimensional approach allows long, complex passage geometries to be created as the CMC forms around the mandrel, rather than having to drill through the material afterward.
Data Source
AI summary
A method for forming a hole within a ceramic matrix composite component includes forming a first core portion for a ceramic matrix composite component; embedding a hollow member into the first core portion at a desired location; wrapping the first core portion with a first ceramic matrix composite material; inserting a rod through the hollow member and into the first core portion; removing the hollow member; assembling a second core portion to the first core portion such that the rod extends into the second core portion; and wrapping the first core portion and the second core portion with a second ceramic matrix composite material.