Ceramic Cooling Hole Machining with Laser Pre-Drilling and Ultrasonics

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Solution Overview

Problem

Efficient machining of cooling holes in ceramic components for gas turbine engines is challenging due to the hardness and brittleness of ceramics, with existing methods like ultrasonic and laser machining facing compatibility issues and reduced machining speed with increasing depth.

Innovation Solution

A method combining laser drilling and ultrasonic machining, where a through-hole is first drilled using a laser and then expanded using ultrasonic machining, with a common chuck system for accurate alignment and abrasive slurry drainage to maintain machining speed, facilitating the formation of distinct sections in cooling holes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If ultrasonic machining is used to machine cooling holes in ceramic components, then machining precision is improved, but machining speed decreases with increasing depth

Engineering Contradiction:

Improvecooling hole geometry precisionVSAvoidmachining speed

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The cooling hole formation process is divided into two distinct stages: first, laser drilling creates an initial through-hole with constant cross-section; second, ultrasonic machining expands a portion of this through-hole to create the final non-uniform cross-section cooling hole geometry. This segmentation allows each process to operate in its optimal performance range.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The laser drilling process performs preliminary action by creating a through-hole that serves as a precursor for the subsequent ultrasonic machining. This pre-formed hole provides a pathway for abrasive slurry drainage and establishes the initial geometry, enabling the ultrasonic machining to focus solely on expanding and shaping the cooling hole with maintained efficiency.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If laser drilling is used to create cooling holes in ceramic components, then machining speed is improved, but machining precision for complex geometries deteriorates

Engineering Contradiction:

Improvemachining speedVSAvoidcooling hole geometry precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The process segments the cooling hole formation into two functional parts: the laser creates the initial through-hole structure efficiently, while the ultrasonic machining subsequently refines and expands the geometry to achieve the precise non-uniform cross-section required for optimal cooling performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The through-hole created by laser drilling serves as an intermediary structure that bridges the two machining processes. It provides the foundation for ultrasonic machining to build upon, enabling the transition from high-speed drilling to precision geometry formation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If a single machine is used for both laser drilling and ultrasonic machining, then device complexity is reduced, but alignment precision between processes deteriorates

Engineering Contradiction:

Improvemachining system complexityVSAvoidthrough-hole alignment precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The fixture design incorporates universal features that are compatible with both laser drilling and ultrasonic machining processes. The same fixture with its standardized chuck interface can be used across different machines, ensuring consistent workpiece positioning and alignment while maintaining system flexibility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 combined approach enhances machining efficiency and accuracy, overcoming the limitations of individual techniques by maintaining consistent machining speed and ensuring precise alignment, effectively producing complex cooling hole geometries in ceramic components.

Implementation Method 1

a laser is used to drill a through-hole in a wall of the workpiece

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

The second machine uses ultrasonic machining to expand a portion of the through-hole to form the second section

Methodology Applied

Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 3

An abrasive slurry used in the process is drained through the through-hole during the ultrasonic machining

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentUS20230193772A1Fabrication of cooling holes using laser machining and ultrasonic machining

Publication Date: 2023.06.22 RTX CORP

AI summary

A method of machining cooling holes includes providing a workpiece in which a cooling hole is to be formed. The cooling hole, once formed, defines distinct first and second sections. The workpiece is secured in a fixture that is mounted in a first machine. In the first machine, a laser is used to drill a through-hole in a wall of the workpiece. The through-hole is spatially common to the first and second sections of the cooling hole. After drilling the through-hole, the fixture with the workpiece secured therein is removed from the first machine and mounted in a second machine. In the second machine, ultrasonic machining is used to expand a portion of the through-hole to form the second section. An abrasive slurry used in the process is drained through the through-hole during the ultrasonic machining.