Monochromatic LED Inspection for Additive Manufacturing Defects
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Solution Overview
Problem
Current inspection techniques are ineffective in detecting surface imperfections such as cracks, discoloration, and foreign materials during the additive manufacturing process, as these imperfections can be camouflaged by the surface color of composite or metallic structures, leading to costly rejections of finished parts.
Innovation Solution
A real-time surface inspection method using multiple ultra-bright organic light emitting diodes in combination with holographic filters to produce uniform monochromatic illumination, allowing feedback cameras to adjust the lighting and detect anomalies by blending background colors, thereby highlighting surface imperfections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inspection techniques are used to detect surface imperfections, then the inspection process is simple, but the detection precision is insufficient because imperfections are camouflaged by surface color
Solution Approach 1:
The patent applies color changes by using multiple LED illumination sources with different color temperatures (e.g., 1000K, 2000K, 5000K, 10000K) to illuminate the workpiece surface. By capturing images under these different color illuminations and processing them to remove color information, the system transforms the appearance of the surface to eliminate camouflage effects, making imperfections detectable regardless of their original color match with the background.
Solution Approach 2:
The patent transitions from conventional single-color or broad-spectrum illumination to multi-dimensional color space illumination by using LEDs across the visible spectrum. This dimensional expansion in illumination color temperature allows the system to capture surface information in multiple spectral dimensions, which are then processed to eliminate color-based camouflage and reveal imperfections that would be invisible under conventional lighting.
2Reliability
If visual inspection is performed after manufacturing, then the inspection process is simple, but substantial cost is lost in materials and machine time
Solution Approach 1:
The patent implements preliminary action by performing inspection during the additive manufacturing process itself rather than after completion. The illumination system and cameras are integrated into the manufacturing chamber, allowing real-time detection of surface imperfections as they form. This enables early termination or correction of defective builds, preventing waste of remaining material and machine time while maintaining manufacturing reliability.
Solution Approach 2:
The system employs feedback by capturing images during manufacturing, analyzing them for imperfections, and providing real-time information about part quality. This feedback loop allows operators to make immediate decisions about continuing or stopping the manufacturing process, ensuring that defective parts are identified and addressed during production rather than discovered later when material and time are already lost.
3Measurement precision
If multiple illumination sources with different color temperatures are used, then the detection capability is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by using a single multi-color-temperature LED illumination system that serves multiple functions: illuminating the workpiece surface, providing spectral information for color removal processing, and enabling detection of various types of surface imperfections. This multi-functional approach consolidates what would otherwise require separate illumination systems for different inspection purposes, managing complexity while maintaining enhanced detection capability.
Solution Approach 2:
The system utilizes parameter changes by varying the color temperature parameter of the LED illumination across a wide range (1000K to 10000K). By controlling and changing this physical parameter, the system can adapt the illumination characteristics to highlight different types of surface features and imperfections. This parameter-based control provides a flexible, programmable approach to enhancing detection capability without requiring physically different illumination sources for each inspection scenario.
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 early detection of imperfections during manufacturing, allowing for process correction or termination, reducing material waste and machine usage inefficiencies, and improving the overall manufacturing efficiency.
Implementation Method 1
multiple ultra-bright organic light emitting diodes
Implementation Method 2
holographic filters to produce uniform monochromatic illumination
Implementation Method 3
capturing a current image of a second light radiation that is scattered or reflected by the target area
Implementation Method 4
capturing a current image of a second light radiation that is scattered or reflected by the target area
Data Source
AI summary
A method for real-time surface imperfection detection for additive manufacturing and 3-D printing parts is provided. The method includes directing a first light radiation using one or more illumination sources, wherein the first light radiation illuminates a target area of a part being manufactured in a uniform chromatic light such that the target area appears to have a substantially uniform monochromatic color; capturing a current image of a second light radiation that is scattered or reflected by the target area using one or more feedback cameras; and analyzing the current image of the second light radiation using at least one of the one or more feedback camera with a previously acquired image to determine whether a surface imperfection exists or does not exist.