Optical Image Analysis for Additive Manufacturing Error Detection

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Solution Overview

Problem

Additive Manufacturing (AM) processes, particularly Selective Laser Melting (SLM), face challenges in quality monitoring and control due to variability in input parameters and boundary conditions, leading to errors that can compound and result in non-functional or non-compliant parts.

Innovation Solution

A method and system for detecting errors in AM processes using optical images analysis, where gray values of pixels in captured images are compared to thresholds based on reference images to identify issues such as warpage and dross formation, enabling non-destructive, in-process inspection and quality control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional quality monitoring methods are used in additive manufacturing, then the process is simple to implement, but the detection sensitivity and accuracy are insufficient to identify errors early

Engineering Contradiction:
Improveerror detection accuracyVSAvoidinspection system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent captures optical images of the build platform at multiple stages during the additive manufacturing process (before melting, during melting, after melting, and after recoating). This preliminary capture of data during the build process enables early error detection before defects compound, resolving the contradiction by implementing detection actions in advance rather than as a post-processing step.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent creates digital copies of the build platform through optical imaging. These image copies are then processed through gray value analysis and comparison with reference images to detect errors. This copying approach enables sophisticated analysis without requiring complex physical inspection equipment, thus improving detection accuracy while managing system complexity.

Inventive Principle:
Principle #26Copying

2Reliability

If comprehensive quality monitoring is implemented throughout the build process, then error detection capability is improved, but the processing time and computational resources increase

Engineering Contradiction:
Improvepart quality reliabilityVSAvoidinspection processing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent divides the build process into distinct stages (before melting, during melting, after melting, after recoating) and captures images at each stage. This segmentation allows for targeted analysis of specific error types at appropriate build stages, improving reliability while reducing unnecessary processing time compared to continuous monitoring of the entire process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs gray value analysis on specific regions of interest in the optical images rather than analyzing every pixel throughout the entire build volume. This partial action approach maintains high reliability for error detection while significantly reducing computational time and resources required for processing.

Inventive Principle:
Principle #16Partial or excessive action

3Ease of manufacture

If optical imaging is used to capture build platform images, then non-destructive inspection is achieved, but the complexity of image processing and analysis increases

Engineering Contradiction:
Improveinspection process simplicityVSAvoidimage processing complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical inspection systems with optical imaging and computational analysis. By using gray value processing and image comparison algorithms, the system achieves sophisticated error detection without requiring complex physical measurement devices, thus maintaining ease of manufacture while managing processing complexity.

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

Solution Approach 2:

The patent transforms optical images into gray value parameters for analysis. This parameter transformation simplifies the image processing by converting visual information into quantitative data that can be compared against reference values, reducing the complexity of analysis while maintaining effective error detection capability.

Inventive Principle:
Principle #35Parameter changes

4Manufacturing precision

If errors are detected early in the build process, then defective parts can be prevented, but the frequency of monitoring requires more resources

Engineering Contradiction:
Improvepart dimensional precisionVSAvoidbuild process efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent implements periodic optical imaging at specific intervals during the build process (before melting, during melting, after melting, after recoating). This periodic monitoring approach enables early error detection that maintains manufacturing precision while avoiding continuous monitoring that would reduce productivity, thus resolving the contradiction between detection frequency and build efficiency.

Inventive Principle:
Principle #19Periodic action

Data Source

PatentUS10719929B2Error detection in additive manufacturing processes
Publication Date: 2020.07.21 MATERIALISE NV
  • US10719929B2 patent drawing
  • US10719929B2 patent drawing
  • US10719929B2 patent drawing

AI summary

The present disclosure relates to the prediction of part and material quality of Additive Manufacturing (AM) processes using layer based images. Described herein are methods and systems for detection of errors in parts built by AM processes such as Selective Laser Melting (SLM). The detection comprises analysis of optical images to identify errors which appear in layers during the AM build process. Errors include but are not limited to warpage of parts and dross formation of overhang surfaces.