Disposable Thin Wall Core Die for Ceramic Casting
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Solution Overview
Problem
Current methods for casting components with complex geometries, such as hollow airfoils for gas turbine engines, are inefficient due to expensive and time-consuming tooling, low casting tolerances, and the need for high-pressure slurry injection, which requires thick, heavy metal core dies.
Innovation Solution
A method involving a thin wall disposable core die with an average thickness of 0.5 to 10 millimeters, made from organic polymers, is used to inject a low viscosity ceramic slurry at reduced pressure, allowing for the formation of a solid ceramic core that can be easily removed and used in investment casting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thick metal core dies are used to withstand high-pressure slurry injection, then the die strength is sufficient, but the die weight and manufacturing cost increase
Solution Approach 1:
The patent employs disposable plastic core dies instead of durable metal core dies. These single-use plastic dies are discarded after one use, eliminating the need for expensive, heavy metal dies while still providing sufficient strength during the casting process. This resolves the contradiction by accepting reduced die longevity in exchange for significantly reduced weight and cost.
Solution Approach 2:
The patent changes the material parameter from metal to plastic and the operational parameter from reusable to single-use. This parameter change allows the die to be lightweight and inexpensive while still functional for its intended single casting operation, resolving the strength-weight tradeoff.
2Reliability
If conventional separate shell and core methods are used, then the casting process is established, but the tooling cost and lead time increase
Solution Approach 1:
The patent merges the shell and core into a single integrated plastic core die structure. The plastic die is formed as one piece that creates both the external shell geometry and internal core geometry simultaneously, eliminating the need for separate tooling and assembly steps. This reduces tooling complexity and lead time while maintaining casting reliability.
Solution Approach 2:
The single plastic core die performs multiple functions: it defines the external shell shape, creates internal passages, and serves as the core itself. This multi-functionality eliminates the need for separate shell and core tooling, reducing overall tooling cost and lead time.
3Quantity of substance
If high viscosity slurry is used in conventional casting, then the slurry can be poured, but the injection pressure requirement increases
Solution Approach 1:
The patent changes the slurry viscosity parameter to a lower range (1-1000 Pa·s) compared to conventional high viscosity slurries. This parameter change allows the slurry to flow more easily into the thin-walled plastic core die under reduced pressure, resolving the contradiction between maintaining slurry integrity and reducing injection pressure requirements.
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 production costs and time by enabling the use of lighter, less expensive core dies and allows for the efficient casting of complex shapes with improved tolerances and reduced operational pressures.
Implementation Method 1
The thin wall disposable core die has an elastic modulus and flexural strength effective to withstand the applied pressures
Implementation Method 2
The slurry is then cured to form a cured ceramic core
Data Source
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AI summary
Disclosed herein is a method comprising injecting into a thin wall disposable core die (100) a slurry having a viscosity of about 1 to about 1,000 Pascal-seconds at room temperature when tested at a shear rate of up to 70 seconds-1 and a flow index of less than 0.6 at a pressure of up to about 7 kilograms-force per square centimeter; wherein the thin wall disposable core die (100) has an average wall thickness of about 1.5 to about 10 millimeters; curing the slurry to form a cured ceramic core; removing the thin wall disposable core die (100) from the cured ceramic core (90); and firing the cured ceramic core to form a solidified ceramic core (90).