CMC Aperture Machining With Angled Back-Side Cutting
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Solution Overview
Problem
Conventional methods for machining apertures in ceramic matrix composite (CMC) components, such as cutting, drilling, and grinding, result in high defect rates, and laser machining is not feasible for all applications due to size limitations, alignment issues, and potential damage to the component.
Innovation Solution
A method involving the selection of a tool with a cutting surface and angle, where the tool is positioned at an angle less than 90 degrees to cut the back surface of the CMC component, followed by completing the aperture from the front surface with the cutting surface normal to it, to form an aperture through the component at a predetermined location and dimension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cutting, drilling, or grinding is used to machine apertures in CMC components, then the machining process can be performed, but 30% to 40% of the machined components have defects
Solution Approach 1:
The machining process is divided into multiple sequential operations: roughing from the first surface, intermediate cutting from the second surface, and finishing from the first surface. This segmentation allows each operation to be optimized independently, removing material in controlled stages that prevent defect propagation and ensure high machining quality with minimal defects.
2Reliability
If laser machining is used to reduce defective components, then yield increases, but the component may be too large to fit the laser tooling or the laser could harm or destroy another portion of the component
Solution Approach 1:
The patent introduces intermediate cutting operations from the second surface as a mediator between roughing and finishing operations. This intermediate step allows material removal that relieves stress and prevents defects without requiring the high energy concentration of laser machining, thereby maintaining high yield while being applicable to large components and complex geometries where laser tooling cannot reach or would cause damage.
3Reliability
If laser machining is used to machine apertures, then yield increases, but the laser cannot be aligned with the component to machine certain features such as blind holes
Solution Approach 1:
The patent applies inverted machining by cutting from the second surface (opposite side) at intermediate stages, rather than only from the first surface where laser alignment would be required. This inversion of the conventional single-sided machining approach eliminates alignment constraints, allowing the process to machine blind holes and features inaccessible to laser tooling while maintaining high yield through controlled intermediate cutting operations.
4Device complexity
If conventional single-sided machining is used, then the process is simple, but the machining quality and defect rate are poor
Solution Approach 1:
The machining process is divided into multiple sequential operations: roughing from the first surface, intermediate cutting from the second surface, and finishing from the first surface. This segmentation allows each operation to be optimized independently, removing material in controlled stages that prevent defect propagation and ensure high machining quality with minimal defects.
Solution Approach 2:
The patent transitions from single-sided machining to multi-sided machining by introducing operations from the second surface. This dimensional change in the machining approach allows intermediate cutting that relieves stress and prevents defects, significantly improving aperture machining quality while maintaining reasonable process complexity through systematic multi-directional material removal.
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 defects and increases the yield of machined components by allowing precise angled cutting and finishing from opposite sides, improving the machining process for CMC components.
Implementation Method 1
cutting the back surface of the component with the tool to a depth less than a thickness of the component
Data Source
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AI summary
Methods and apparatus for forming an aperture (102) in a composite component (100) are provided. For example, a method (200) for forming an aperture (102) in a ceramic matrix composite (CMC) component (100) comprises, based on a final dimension of the aperture (102), selecting a tool (106) having a tool (106) size and a cutting surface (108); selecting an angle at which to cut the component (100) with the tool (106); cutting a back surface (110) of the component (100) with the tool (106), the cutting surface (108) positioned at the angle; repositioning the tool (106) relative to the component (100); and cutting the aperture (102) through to its final dimension. The tool (106) may be a core drill (106) with a diameter within a range of 60% to 90% of the aperture (102) final dimension. The angle may be within a range of 10° to 60° with respect to the back surface (110). The aperture (102) may be cut through to its final dimension from a front surface (112) of the component (100).