Optical Melt Pool Monitoring for Additive Manufacturing Quality Control
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Solution Overview
Problem
Existing additive manufacturing processes lack non-destructive methods for verifying the integrity of parts, as conventional quality assurance testing often requires destructive methods that cannot be applied to production parts.
Innovation Solution
The use of optical sensing techniques, such as monitoring temperature and voltage data with pyrometers and photodiodes, to track in-process physical phenomena and determine quality metrics like Half Power Bandwidth (HPBW), allowing for real-time process control and defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If destructive testing is used to verify part quality, then measurement precision is improved, but the part is destroyed and cannot be used for production
Solution Approach 1:
The patent replaces mechanical contact-based sensing with optical sensing. Optical sensors detect thermal radiation and reflected light from the melt pool region, enabling non-contact measurement of temperature and process quality without physical interference or destruction to the part being manufactured
Solution Approach 2:
The patent monitors changes in optical parameters (intensity, wavelength, temporal characteristics) of radiation from the melt pool to infer temperature and quality metrics. By analyzing how these optical parameters change during the additive manufacturing process, the system can detect anomalies and verify quality without destructive testing
2Productivity
If optical sensing is implemented for real-time monitoring, then productivity is improved through non-destructive testing, but device complexity increases
Solution Approach 1:
The optical sensing system is designed to perform multiple functions: temperature measurement, melt pool geometry characterization, and quality defect detection. By using a single optical sensing platform that can extract multiple quality metrics from the same optical signals, the system reduces overall device complexity while maintaining high productivity
Solution Approach 2:
The patent uses optical radiation as an intermediary carrier of information about the melt pool state. Rather than directly measuring temperature or geometry, the system detects optical signals that naturally emanate from or reflect off the hot melt pool, converting these signals into quality metrics through analysis algorithms
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 approach enables non-destructive verification of part integrity, allows for real-time process adjustments to prevent defects, and improves the overall quality of additive manufacturing products.
Implementation Method 1
One such IPQM is the Half Power Bandwidth (HPBW) based on thermal data collected by a pyrometer or photodiode
Implementation Method 2
Optical sensors can be used to track the evolution of in-process physical phenomena by tracking the evolution of their associated in-process physical variables
Data Source
AI summary
This disclosure describes an additive manufacturing method that includes monitoring a temperature of a portion of a build plane during an additive manufacturing operation using a temperature sensor as a heat source passes through the portion of the build plane; detecting a peak temperature associated with one or more passes of the heat source through the portion of the build plane; determining a threshold temperature by reducing the peak temperature by a predetermined amount; identifying a time interval during which the monitored temperature exceeds the threshold temperature; identifying, using the time interval, a change in manufacturing conditions likely to result in a manufacturing defect; and changing a process parameter of the heat source in response to the change in manufacturing conditions.