Additive Manufacturing Thermal Monitoring for Defect Control
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Solution Overview
Problem
Current additive manufacturing processes lack non-destructive methods for verifying the integrity of parts, as conventional quality assurance testing often requires destruction of the part, making it impractical for production use.
Innovation Solution
The implementation of optical sensing techniques, specifically using Half Power Bandwidth (HPBW) metrics derived from thermal data collected by pyrometers or photodiodes, to monitor and control the additive manufacturing process, allowing for real-time detection of manufacturing defects and adjustments to process parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional quality assurance testing is used, then part quality can be verified, but the part must be destroyed for testing
Solution Approach 1:
The patent replaces mechanical/destructive testing methods with optical sensing techniques. Pyrometers and photodiodes detect thermal radiation and light emissions from the melt pool during additive manufacturing, enabling non-contact, non-destructive quality monitoring. This substitution allows real-time detection of manufacturing defects without damaging the part.
Solution Approach 2:
The patent introduces optical sensors (pyrometers and photodiodes) as intermediaries between the manufacturing process and quality assessment. These sensors detect thermal and optical signatures of the melt pool, converting physical process parameters into measurable signals that indicate quality without direct contact with or damage to the part.
2Reliability
If optical sensing techniques are implemented, then non-destructive quality monitoring is enabled, but system complexity increases
Solution Approach 1:
The patent employs multi-functional optical sensors that simultaneously perform multiple measurement tasks. Pyrometers and photodiodes monitor both thermal profiles and melt pool characteristics, enabling comprehensive quality assessment through a single integrated sensing system rather than multiple specialized devices.
Solution Approach 2:
The manufacturing process itself generates the signals needed for monitoring. The melt pool's thermal radiation and light emissions provide inherent information about process quality, eliminating the need for external test equipment. The process 'serves its own monitoring needs' through its own physical emissions.
3Productivity
If real-time process monitoring is performed, then manufacturing defects can be prevented, but measurement precision requirements increase
Solution Approach 1:
The patent performs preliminary detection of quality issues during the manufacturing process itself, before defects become permanent. By monitoring thermal profiles and melt pool characteristics in real-time, the system identifies anomalies early and enables corrective action before defective parts are completed, preventing waste and rework.
Solution Approach 2:
The patent implements a feedback loop where optical sensors continuously monitor process parameters and provide real-time information about melt pool conditions. This feedback enables dynamic adjustment of manufacturing parameters to maintain optimal process conditions and prevent defect formation, creating a closed-loop control system.
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 non-destructive quality assurance and process control, preventing defects by accurately estimating thermal profiles and adjusting parameters in real-time, thus ensuring the quality of the additive manufacturing process without damaging the part.
Implementation Method 1
optical sensing techniques such as, e.g., quality inference, process control, or both, to additive manufacturing processes. 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. Herein optical can include that portion of the electromagnetic spectrum which include near infrared (IR), visible and well as near ultraviolet (UV).
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.