Flexible Wax Pattern Tool for Ceramic Core Support
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Solution Overview
Problem
The investment casting process is expensive and time-consuming, with limitations in design flexibility due to the complexity and cost of traditional wax pattern tooling, which restricts advancements in components like next-generation gas turbine engines with increased firing temperatures and larger hot gas path components.
Innovation Solution
The use of a flexible wax pattern mold with a hybrid tool featuring a flexible insert and ceramic inserts to support the ceramic core during wax injection, allowing higher pressures and reducing core damage, while enabling precise location and surface topography replication, and incorporating reactive elements or active devices for enhanced functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional rigid wax pattern tooling is used, then manufacturing precision can be maintained, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent applies a flexible liner made of elastomeric material that conforms to the ceramic core surface, replacing complex rigid tooling structures. The flexible liner can be removed easily after wax injection without requiring complex extraction mechanisms, thereby reducing device complexity while maintaining manufacturing precision through the conformal contact and support provided during the process.
2Productivity
If higher wax injection pressure is used, then productivity and casting yield improve, but ceramic core damage increases
Solution Approach 1:
The flexible liner is positioned beforehand to make contact with the ceramic core, providing a cushioning effect that absorbs and distributes the forces generated during high-pressure wax injection. This pre-positioned protective layer prevents direct transmission of harmful forces to the fragile ceramic core, enabling higher injection pressures to be used safely to improve productivity and casting yield.
3Adaptability or versatility
If complex internal cooling passages are incorporated, then product functionality improves, but tooling cost and manufacturing time increase
Solution Approach 1:
The flexible liner enables easy adaptation to complex internal cooling passage geometries by conforming to the ceramic core's intricate surface features. The liner can be easily removed and replaced for different core designs without requiring expensive, time-consuming custom tooling fabrication, thereby improving design flexibility while reducing tooling manufacturing time and cost.
Data Source
Figure 1~3
Figure 4A~4C
Figure 4D~4G
AI summary
An investment casting process wherein the wax pattern tool (42) is flexible to provide compliant support for an enclosed ceramic core (10) and to facilitate removal of the tool from the cast wax pattern (52) even when the cast shape would otherwise require multiple pull planes. Positioning pins (108) may extend from the flexible tool to make compliant contact against the core during the wax injection step. The pins may cooperate with a pedestal (128) formed on the core to support the core along multiple axes during wax injection, thereby allowing a higher wax injection pressure without damage to the core.