Single-Crystal Turbine Blade Casting with Linked Ceramic Cores

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Solution Overview

Problem

The high cost and time-consuming nature of manufacturing single crystal turbomachine blades for gas turbine engines due to the lengthy solidification process and numerous processing steps in existing crystallographically-oriented casting methods.

Innovation Solution

A process involving a ceramic core piece with two or four ceramic core elements and a clamping part, coated with wax, which is then cast using a crystallographically-oriented metal casting process, allowing for efficient handling and separation of blades post-casting, reducing operational time and cost by half.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If single crystal casting process is used to manufacture turbomachine blades, then mechanical properties at high temperatures are improved, but manufacturing cost and time increase significantly

Engineering Contradiction:
Improvemechanical properties at high temperaturesVSAvoidmanufacturing speed
Core Design Contradiction:
StrengthVSProductivity

Solution Approach 1:

The blade is divided into multiple segments (first blade, second blade, etc.) that are cast simultaneously in a single crystal structure within one mold cavity. This segmentation allows multiple blades to be produced in parallel during one solidification cycle, dramatically increasing productivity while maintaining the mechanical properties of single crystal blades.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple blade segments are merged into a single cast piece during the crystallographically-oriented solidification process. The blades share a common crystal structure and are formed simultaneously from the same molten metal, allowing them to be manufactured together in one operation rather than individually, thus reducing total manufacturing time.

Inventive Principle:
Principle #5Merging (Combining)

2Strength

If single crystal casting process is used to manufacture turbomachine blades, then mechanical properties at high temperatures are improved, but manufacturing cost increases

Engineering Contradiction:
Improvemechanical properties at high temperaturesVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The mold is designed with multiple cavities or compartments that can accommodate several blade segments simultaneously. This allows the production of multiple blades in one casting cycle, spreading the fixed costs of the single crystal casting process (such as mold preparation, heating, and solidification time) across multiple products, thereby reducing the cost per blade.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple blades are combined into a single cast piece that is processed together through the entire single crystal casting cycle. This merging eliminates the need for separate processing steps for each blade, reducing cumulative costs associated with multiple independent manufacturing operations.

Inventive Principle:
Principle #5Merging (Combining)

3Productivity

If multiple blades are cast together as a single piece, then productivity is improved, but handling and processing complexity increases

Engineering Contradiction:
Improvemanufacturing efficiencyVSAvoidhandling complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

A separable connection structure (such as a common platform or root structure) is designed into the cast piece that allows the individual blades to be easily separated after casting. This extraction mechanism enables the complex multi-blade assembly to be divided into manageable individual components without requiring complex separation processes, thus reducing handling complexity while maintaining the productivity benefits of simultaneous casting.

Inventive Principle:
Principle #2Taking out (Extraction)

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 process enables the efficient manufacturing of turbomachine blades with reduced operational time and cost, while maintaining the mechanical properties required for high-temperature applications, by allowing secure handling and processing of complex-shaped blades as a linked cast piece before separation.

Implementation Method 1

a molten wax material is applied to the outside of the ceramic core piece in the wax forming device and the wax is allowed to solidify

Methodology Applied
Scientific EffectSolidification: Freezing

Implementation Method 2

at least two turbomachine blades are cast using a crystallographically-oriented metal casting process

Methodology Applied
Scientific EffectCrystallographically-oriented solidification: Crystallisation

Data Source

PatentEP4112204B1Manufacturing process for blades of a turbo machine
Publication Date: 2023.10.25 ROLLS ROYCE PLC
  • EP4112204B1 patent drawingFigure 1
  • EP4112204B1 patent drawingFigure 2
  • EP4112204B1 patent drawingFigure 3

AI summary

A manufacturing process for blades (5) of a turbomachine, e.g. a gas turbine engine for an aircraft. In the process: a) a ceramic core piece (1) that comprises at least two ceramic core elements (1', 1", 1‴, 1ʺʺ) and a clamping part (2) that connects the ceramic core elements, is positioned in a wax forming device (100), subsequently; b) a molten wax material (W) is applied to the outside of the ceramic core piece (1) in the wax forming device (100) and the wax is allowed to solidify, and subsequently; c) at least two turbomachine blades (5) are cast using a crystallographically-oriented metal casting process and the wax (W) and the ceramic core piece (1) are removed.