Segmented Mandrel Removal for Complex CMC Airfoil Preforms
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Solution Overview
Problem
The challenge of removing tooling from complex geometry ceramic matrix composite (CMC) parts without damaging the preform during the densification process, particularly when the tooling is used as a partially enclosed core or has substantial surface deviations.
Innovation Solution
The use of segmented mandrels, which are either longitudinally or transversely segmented, allowing for sequential removal of individual pieces to minimize damage to the preform, and may include features like apertures for hook insertion or locking systems to facilitate extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a unitary mandrel is used to form complex geometry CMC parts, then the preform can be properly shaped and supported during densification, but the mandrel cannot be removed without damaging the preform
Solution Approach 1:
The mandrel is divided into multiple separable segments or pieces that can be independently removed from the preform. Each segment can be extracted through separate access points, allowing complete mandrel removal without damaging the cured CMC preform structure.
Solution Approach 2:
The mandrel segments are designed to be extractable through openings or access points in the preform. The segments can be pulled out individually after densification, leaving no damage to the final CMC component.
2Manufacturing precision
If the mandrel geometry closely matches the preform geometry, then the preform maintains proper shape, but the mandrel becomes difficult to extract
Solution Approach 1:
By segmenting the mandrel, each piece can be designed with slight geometric variations that allow extraction through specific access points while maintaining overall preform shape fidelity during the forming process.
Solution Approach 2:
The mandrel segments are removed through a different dimensional approach - extracting through access points or openings rather than attempting to pull a unitary mandrel through the entire preform length, changing the extraction pathway from one dimension to another.
3Adaptability or versatility
If the mandrel is used as a partially enclosed core, then complex internal geometries can be formed, but the mandrel creates substantial surface deviations that prevent removal
Solution Approach 1:
The mandrel is segmented into multiple pieces that can be independently accessed and removed. This segmentation allows the mandrel to serve as an enclosed core for forming complex internal geometries while enabling subsequent removal of individual segments through access points.
Solution Approach 2:
Access points or openings in the preform serve as intermediaries that allow mandrel segment extraction. These intermediaries enable the removal function without compromising the structural integrity or surface quality of the final CMC component.
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
Enables the safe and efficient removal of mandrels from complex CMC parts by reducing the risk of damage to the preform, ensuring the integrity of the final CMC component.
Implementation Method 1
densifying the ceramic fabric using chemical vapor infiltration (CVI) to form the CMC airfoil
Data Source
AI summary
A mandrel suitable for supporting an airfoil preform includes a first piece extending along a longitudinal axis of the mandrel, and a second piece in physical contact with the first piece at first interface region and extending along the longitudinal axis of the mandrel. The first piece is formed from a first material, and the second piece is formed from a second material.