Turbine Shroud MIM with Removable Insert for Undercut Regions

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Solution Overview

Problem

Current metal injection molding (MIM) processes face challenges in manufacturing complex turbine engine parts with undercut regions due to die lock issues, which limit geometry complexity and require additional machining or costly tooling, making it difficult to open the mold without damaging the part.

Innovation Solution

Incorporating removable inserts, such as telescoping or collapsible tools, into the mold to support and shape undercut regions during the MIM process, allowing the mold to be opened without damaging the part and eliminating the need for additional machining steps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional MIM mold design is used for simple geometries, then manufacturing cost is reduced and production efficiency is improved, but complex parts with undercut regions cannot be manufactured without die lock

Engineering Contradiction:

Improvegeometry complexityVSAvoidmold opening difficulty

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The mold is divided into multiple independent segments: a stationary mold body and a movable insert. The insert can be independently removed from the mold cavity after injection, allowing the mold to be opened without damaging the part. This segmentation enables manufacturing of complex geometries with undercuts that would otherwise cause die lock.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A removable insert acts as an intermediary element between the mold cavity and the final part. The insert temporarily supports the part geometry during injection, then can be easily removed, serving as a mediator that enables mold opening for complex shapes without requiring complex slide mechanisms.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Shape

If multiple slides are added to create undercut regions, then complex shapes can be formed, but tooling cost increases and process complexity increases

Engineering Contradiction:

Improveundercut region geometryVSAvoidmold structure complexity

Core Design Contradiction:

ShapeVSDevice complexity

Solution Approach 1:

The undercut-forming functionality is extracted from the main mold body and placed into a separate, removable insert. This allows the insert to be independently designed and optimized for complex geometries while keeping the main mold structure simple and easy to manufacture.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The insert is designed to be movable and removable from the mold cavity, providing dynamic flexibility. This allows the mold to transition from a closed state during injection to an open state for part removal, enabling complex shapes without permanent complex mold structures.

Inventive Principle:

Principle #15Dynamics

3Shape

If multiple slides are added to create undercut regions, then complex shapes can be formed, but manufacturing cost increases

Engineering Contradiction:

Improveundercut region geometryVSAvoidtooling cost

Core Design Contradiction:

ShapeVSEase of manufacture

Solution Approach 1:

The insert is designed as a relatively simple, removable component that can be easily manufactured and replaced if needed. This approach is more cost-effective than creating expensive, complex multi-slide mold structures, as the insert can be made from standard materials and processes.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Manufacturing precision

If MIM is used for simple geometries, then near-net shape is achieved with minimal machining, but complex parts require additional machining steps

Engineering Contradiction:

Improvenear-net shape accuracyVSAvoidadditional machining requirements

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

By segmenting the mold into a removable insert, the MIM process can now achieve near-net shape for complex geometries with undercuts, eliminating the need for additional machining steps that would otherwise be required to create these features.

Inventive Principle:

Principle #1Segmentation

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 production of complex turbine engine parts with undercut regions by preventing die lock, reducing manufacturing costs, and simplifying the production process while maintaining part integrity.

Implementation Method 1

injecting a metal injection molding (MIM) feedstock into the mold cavity and around the removable insert to form a shroud green body

Methodology Applied

Scientific EffectInjection molding:

Implementation Method 2

sintering the shroud green body to form the shroud body

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS20240173771A1Method for making turbine engine components using metal injection molding

Publication Date: 2024.05.30 ROLLS ROYCE CORP

AI summary

A method for manufacturing a turbine shroud segment with at least one undercut region. The method includes forming a removable insert including an external surface corresponding to at least a portion of a wall of the undercut region in the turbine shroud segment; placing the removable insert in a mold including a mold cavity corresponding to a shape of the turbine shroud segment; injecting a metal injection molding (MIM) feedstock into the mold cavity and around the removable insert to form a shroud green body with the at least one undercut region; and, sintering the shroud green body to form the shroud body.