Normalized Thermal Sensor Curves for Additive Manufacturing Defect Detection
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Solution Overview
Problem
Conventional quality assurance methods for additive manufacturing are limited, particularly in non-destructively verifying the integrity of parts produced, as data from wide-area thermal sensors can be biased by varying distances and scan lengths, making it difficult to accurately characterize the quality of the parts.
Innovation Solution
A method involving the use of optical temperature sensors to monitor a heat source scanning across a powder bed, generating characteristic curves from intensity and duration data, and comparing these to baseline curves to identify defects, while accounting for variations in scan length and distance using additional sensors to correct for geometric errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a wide area thermal sensor is used to monitor the additive manufacturing process, then the measurement coverage is improved, but the measurement precision deteriorates due to varying distances between the sensor and different portions of the build plane
Solution Approach 1:
The patent applies parameter changes by introducing geometric parameters (distance, scan length, orientation) as correction factors. The system measures these geometric parameters and uses them to normalize the thermal sensor data, transforming the raw measurements into corrected values that account for the varying sensor-to-build-plane distance and scan characteristics.
Solution Approach 2:
The patent replaces direct physical measurement with a computational approach. Instead of using a single-point sensor that physically touches or is extremely close to the build plane, the system uses a wide-area thermal sensor combined with geometric correction algorithms. This substitution allows non-contact measurement while compensating for distance effects through mathematical normalization.
2Adaptability or versatility
If the heat source scans across different portions of the powder bed, then the manufacturing versatility is improved, but the measurement consistency deteriorates due to variations in scan length and distance
Solution Approach 1:
The system changes the approach from assuming constant measurement conditions to dynamically adjusting for varying parameters. By measuring and recording scan length, distance, and orientation for each scan, the system transforms inconsistent raw data into normalized characteristic curves that can be reliably compared across different scan conditions.
Solution Approach 2:
The patent implements feedback by using additional sensors to measure geometric parameters (distance, scan length, orientation) and feeding this information back into the data processing system. This feedback loop allows the system to automatically correct for variations in scan conditions, maintaining measurement consistency despite changes in manufacturing parameters.
3Measurement precision
If additional sensors are added to correct for geometric errors, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent introduces geometric parameters (distance, scan length, orientation) as intermediary correction factors. These intermediaries bridge the gap between the simple wide-area thermal sensor and the need for precise measurements. Rather than adding complex sensor hardware, the system uses these measurable geometric parameters to mediate the correction process through computational normalization.
Solution Approach 2:
The patent substitutes additional complex measurement hardware with a computational correction system. Instead of adding more thermal sensors or complex positioning systems, the invention uses simple geometric measurements combined with normalization algorithms to achieve high measurement precision, replacing mechanical complexity with mathematical processing.
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 verification of additive manufacturing parts by accurately identifying defects through normalized characteristic curves, ensuring consistent quality and reducing errors associated with distance and scan length variations.
Implementation Method 1
monitoring a heat source scanning across a powder bed using an optical temperature sensor
Implementation Method 2
the heat source melts the incrementally added powder by welding regions of the powder layer creating a moving molten region
Implementation Method 3
the heat source melts the incrementally added powder by welding regions of the powder layer
Data Source
AI summary
The disclosed embodiments relate to the monitoring and control of additive manufacturing. In particular, a method is shown for removing errors inherent in thermal measurement equipment so that the presence of errors in a product build operation can be identified and acted upon with greater precision. Instead of monitoring a grid of discrete locations on the build plane with a temperature sensor, the intensity, duration and in some cases position of each scan is recorded in order to characterize one or more build operations.