On-Axis Melt Pool Sensing for Real-Time Laser AM Defect Control

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Solution Overview

Problem

Additive manufacturing processes face challenges with defect formation due to temperature fluctuations, leading to time-consuming post-production scanning and potential part failure, which increases production costs and time.

Innovation Solution

A system with on-axis sensing and real-time control using a detection system with independently filtered channels and a high-speed FPGA or ASIC to monitor the melt pool temperature profile, enabling in situ defect detection and healing during the manufacturing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If post-production scanning is used to detect defects, then defect detection accuracy is improved, but production time and costs increase

Engineering Contradiction:
Improvedefect detection accuracyVSAvoidproduction time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs defect detection during the additive manufacturing process itself, before production is complete. The optical sensor continuously monitors the melt pool temperature and detects anomalies in real-time, allowing defects to be identified and addressed during manufacturing rather than requiring separate post-production scanning.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements real-time feedback control by continuously monitoring melt pool temperature through optical sensing and using this information to detect defects as they form. The temperature data provides immediate feedback about process quality, enabling in-situ defect detection without delaying production.

Inventive Principle:
Principle #23Feedback

2Reliability

If post-production scanning is used to detect defects, then defect detection accuracy is improved, but production costs increase

Engineering Contradiction:
Improvedefect detection accuracyVSAvoidproduction cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The system performs defect detection during the additive manufacturing process itself, before production is complete. The optical sensor continuously monitors the melt pool temperature and detects anomalies in real-time, allowing defects to be identified and addressed during manufacturing rather than requiring separate post-production scanning.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements real-time feedback control by continuously monitoring melt pool temperature through optical sensing and using this information to detect defects as they form. The temperature data provides immediate feedback about process quality, enabling in-situ defect detection without delaying production.

Inventive Principle:
Principle #23Feedback

3Reliability

If real-time temperature monitoring is implemented, then in-layer defect healing becomes possible, but system complexity increases

Engineering Contradiction:
Improvepart qualityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system implements real-time feedback control by continuously monitoring melt pool temperature through optical sensing and using this information to detect defects as they form. The temperature data provides immediate feedback about process quality, enabling in-situ defect detection without delaying production.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system replaces complex mechanical measurement systems with optical sensing. By using optical sensors to monitor melt pool temperature through light absorption and emission characteristics, the system achieves precise temperature monitoring without mechanical contact or complex instrumentation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Measurement precision

If on-axis sensing with multiple filtered channels is used, then temperature profile measurement accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvetemperature profile accuracyVSAvoiddetection system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The detection system divides the spectral measurement into multiple independently filtered channels, each monitoring specific wavelength ranges. This segmentation of the spectral information allows precise temperature measurement through multi-spectral analysis while keeping each individual channel relatively simple.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system measures temperature by analyzing changes in spectral parameters across multiple wavelength channels. By monitoring how the spectral response varies with temperature and comparing across different filtered channels, the system achieves high temperature measurement precision through parameter analysis rather than complex hardware.

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

Reduces the need for post-production scanning by allowing real-time defect detection and healing, significantly decreasing production time and costs while ensuring part quality.

Implementation Method 1

a detection system disposed for on axis sensing of a temperature profile of the melt pool where the detection system includes a plurality of independently filtered channels that each monitor a spectral response of the melt pool to determine the temperature profile based on the spectral response

Methodology Applied
Scientific EffectSpectral response monitoring: Absorption Spectroscopy

Implementation Method 2

an energy source such as a laser operable to emit a beam to heat a powder bed to form a melt pool

Methodology Applied
Scientific EffectLaser heating: Laser

Data Source

PatentUS20250205784A1Real Time Control Of Laser Additive Manufacturing With High Speed Optically Calibrated On Axis Sensing
Publication Date: 2025.06.26 JOHNS HOPKINS UNIVERSITY
  • US20250205784A1 patent drawing
  • US20250205784A1 patent drawing
  • US20250205784A1 patent drawing

AI summary

A system for controlling an additive manufacturing processing may include an energy source operable to emit a beam to heat a powder bed to form a melt pool, a detection system disposed for on axis sensing of a temperature profile of the melt pool where the detection system includes a plurality of independently filtered channels that each monitor a spectral response of the melt pool to determine the temperature profile based on the spectral response of the plurality of independently filtered channels, and a control system comprising a high speed FPGA or ASIC operably coupled to the detection system to receive the temperature profile and define a control response for controlling operation of the energy source.