Ultrasonic Needle Drilling for Low-Damage Composite Perforations

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Solution Overview

Problem

Conventional methods for forming perforations in composite materials, such as acoustic liners, are time- and capital-intensive, requiring expensive tooling and frequent drill bit replacements, and are challenging due to the difficulty in drilling through composite materials without damaging them.

Innovation Solution

The use of ultrasonic drilling techniques, where a tool with a longitudinal axis orthogonal to the workpiece surface is vibrated at an operating frequency to form holes without rotation or the use of a slurry or cooling fluid, allowing for efficient formation of multiple holes simultaneously in composite materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional drilling methods are used to form perforations in composite materials, then holes can be drilled through the material, but the process is time-consuming and capital-intensive requiring frequent drill bit replacements

Engineering Contradiction:

Improvedrilling speedVSAvoidbuild cycle time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent applies ultrasonic vibration to the drilling tool at high frequency (20-100 kHz) to enable rapid material removal through micro-chipping and erosion mechanisms, dramatically increasing drilling speed compared to conventional rotational drilling while reducing tool wear and build cycle time

Inventive Principle:

Principle #18Mechanical vibration

2Ease of manufacture

If conventional rotational drilling is used on composite materials, then perforations can be formed, but expensive tooling is required and drill bits wear quickly requiring frequent replacement

Engineering Contradiction:

Improvetooling costVSAvoiddrill bit life

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The patent replaces the conventional rotational mechanical cutting system with an ultrasonic vibration-based micro-chipping and erosion system, eliminating the need for expensive rotational drill bits and reducing tooling costs while extending tool life through reduced mechanical stress and wear on the drilling tool

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If conventional drilling methods are used on composite materials, then holes can be drilled, but the process is challenging due to difficulty in drilling through composite materials without damaging them

Engineering Contradiction:

Improveperforation qualityVSAvoidcomposite material damage

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The ultrasonic vibration applied to the drilling tool creates high-frequency micro-chipping and erosion that removes material progressively without generating the lateral forces and heat associated with rotational drilling, thereby preventing delamination, fiber pull-out, and other forms of damage to the composite material while maintaining high manufacturing precision

Inventive Principle:

Principle #18Mechanical vibration

Solution Approach 2:

The patent changes the fundamental drilling parameters from rotational speed and feed rate to ultrasonic frequency and vibration amplitude, creating a new regime of material removal that is gentler on composite materials while achieving the required perforation quality

Inventive Principle:

Principle #35Parameter changes

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 method significantly reduces the time and cost associated with forming perforations, improves the efficiency of the drilling process, and minimizes damage to the composite materials, enabling the production of acoustic liners with high precision and reduced tool wear.

Implementation Method 1

a tool with a longitudinal axis orthogonal to the workpiece surface is vibrated at an operating frequency to form holes

Methodology Applied

Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 2

ultrasonic drilling relies on axial vibrations to essentially hammer the bit into the material... remove material from the workpiece by micro-chipping or erosion

Methodology Applied

Scientific EffectMicro-chipping: Abrasion

Implementation Method 3

The slurry also serves as a coolant to keep the material and bit cool so as to prevent damage to the workpiece and bit

Methodology Applied

Scientific EffectCooling: Cooling

Implementation Method 4

The slurry is returned to slurry tank 18 via slurry return line 24, which serves to carry debris away from the cutting area

Methodology Applied

Scientific EffectFluid flow: Convection

Data Source

PatentUS12330258B2Methods of ultrasonic drilling for forming perforations in composite materials

Publication Date: 2025.06.17 THE BOEING CO

AI summary

Methods of ultrasonic drilling may be used to form perforated sheets by forming holes through a workpiece using a needle or needle array operatively coupled to an ultrasonic actuator. The needle is brought to repeatedly contact the surface of the workpiece at an ultrasonic operating frequency, thereby forming the hole through the workpiece. Such steps are repeated to form a plurality of holes in the workpiece, thereby forming a perforated sheet which may be used in an acoustic liner for noise attenuation. The workpiece may be heated while the holes are formed, via a remote heating unit that locally heats a portion of the workpiece.