Automated Optical Inspection

What Is Automated Optical Inspection Machine?

Automated optical inspection machine (AOI) utilizes the transmission characteristics of glass, and installs detection lens at the bottom, making sure the appearance and sizes of metal stamping components or plastic injection parts are in spec. Automated optical inspection machine is also usually equipped with high standard anti-error system, such as abnormal automatic shutdown alarm, automatic confirmation of test items, automatic shutdown at specific number, continuous abnormalities (such as 30 consecutive NG) automatic shutdown, and so on.

The Process of an Automated Optical Inspection Machine

The inspection process of an automatic optical inspection machine involves the following steps:

1. Preparation: Setting up the AOI machine with the appropriate inspection program and parameters for the specific type of components or products being inspected.

2. Loading: Placing the components or products to be inspected onto the conveyor or fixture of the AOI machine.

3. Image Acquisition: The AOI machine captures high-resolution images of the components or products from multiple angles using cameras and specialized lighting.

4. Image Processing: The captured images are processed by the AOI software to enhance contrast, eliminate noise, and prepare them for defect detection.

5. Defect Detection: The processed images are analyzed to identify defects, such as scratches, misalignment, soldering issues, missing components, or other anomalies. The AOI software compares the captured images with reference images or predefined criteria to determine if any defects are present.

6. Classification and Segmentation: Detected defects are classified based on severity and type. The AOI software may also segment the defects to provide detailed information about their location on the components or products.

7. Decision Making: Based on the analysis results, the AOI system makes decisions about whether a component or product is acceptable or requires further action, such as rework or rejection.

8. Reporting: Inspection results are documented and reported, often including images of detected defects and statistical data about the inspection process.

9. Sorting and Unloading: Components or products are sorted based on the inspection results. Defective items may be sent for rework or disposal, while acceptable items continue along the production line.

10. Feedback Loop: Inspection data and results are used to improve the manufacturing process, identify trends, and make adjustments to prevent similar defects in the future.

The Classification of Automated Optical Inspection Machine

1. Appearance Defect Detection: AOI machines can identify defects on the appearance of products, such as scratches, stains, color variations, and printing imperfections.

2. Dimension Measurement: AOI machines can accurately measure product dimensions, positions, and spacing to ensure compliance with specifications.

3. Welding Quality Inspection: For welded products, AOI machines can inspect the integrity, position, and quality of welds, as well as potential welding defects.

4. Component Alignment and Polarity Detection: AOI machines can confirm correct component placement and detect component polarity to avoid assembly errors.

5. Print Quality Inspection: AOI machines can examine the print quality on printed circuit boards, including print position, accuracy, and defects.

6. Assembly Quality Inspection: AOI machines can detect defects during product assembly, such as misalignment and improper stacking of parts.

7. Missing and Mismatch Detection: AOI machines can detect whether there are missing components or incorrect assemblies in the product.

8. Identification and Barcode Inspection: AOI machines can recognize product markings and barcodes to ensure accuracy and clarity.

9. Solder and Flux Inspection: AOI machines can inspect the soldering process for proper solder and flux distribution, ensuring reliable solder connections.

10. Surface Defect Detection: AOI machines can detect surface defects on products, such as bubbles, cracks, and indentations.
    
    

These classifications showcase the diverse functionalities of automated optical inspection machines in the manufacturing process, contributing to product quality and production efficiency.

The Examples of Automated Optical Inspection Machine

Part Surface Defects / Cracks / Inner and Outer Diameter / Height

The Benefits of Using An Automated Optical Inspection Machine

Throughout the process, automated optical inspection machine can offer -

• Higher inspection accuracy and stability
• More comprehensive inspection criteria, utilizing multiple angles to detect imperfections invisible to the naked eye
• Reduced scrap rate, increased first-pass yield of products
• Shortened inspection time, enhanced production efficiency
• Decreased reliance on manpower, lowered labor costs 

The Specifications of Layana Automated Optical Inspection Machine

• 360° all-round inspection
• 1 to 10 cameras can be added depending on the inspection project
• Detection range: Ø3 mm ~ Ø25 mm
• Accuracy (in pixels): ±1
• Detection speed: Up to 1,000 pcs/min
• Applicable products: Nuts, electronic screws, automotive repair parts, basic appearance and dimension inspection of rubber and plastic parts.
   

The FAQs

Q: How does the AOI machine distinguish between bright and dark surfaces when using lenses with apertures ranging from 1.4 to 16?

A: To differentiate between bright and dark surfaces, lens replacement can be employed as a solution. In the past, there were instances of misclassifying defective products as acceptable due to the type of light source used. Therefore, after discussions with CCD manufacturers in April 2015, it was decided to change the lens to coaxial lighting to address this issue. This change led to a noticeable improvement as the previous ring light setup was prone to misjudging products with surface defects as compliant.

Q: How is micro-deformation in components detected?

A: For components with micro-deformation, Layana currently utilizes images captured by CCD cameras for quality assessment. However, due to limitations in camera pixel accuracy, this can affect the determination process. To address this, Layana has integrated a height detector (similar to the concept of manual GO/NO-GO inspection) before the conveyor belt. If the height is within acceptable parameters, the component proceeds to the inspection glass plate; otherwise, it cannot pass through the fixture. This design approach compensates for the limitations of optical recognition.

Summary

Automated Optical Inspection (AOI) machines have become crucial tools for manufacturers to enhance productivity and reduce costs. The limitations of manual inspection in terms of efficiency and precision make it challenging to meet the increasing demands for product quality. The Layana team has been continuously improving their inspection methods while using AOI machines, aiming for the most accurate and efficient inspection results. Layana offers automated optical inspection services for components, enhancing quality management capabilities to meet customer demands for comprehensive product inspection.