Principles of Vision Inspection Systems: A Beginner’s Guide

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food quality inspector checking bottled products

Inspecting products is a vital step in the manufacturing production line. Errors can occur during production, but standardized inspections ensure that those errors don’t make it out of the manufacturing facility.

But a full, tactile, manual inspection of every good your company produces can be incredibly time-consuming and labor-intensive. Implementing vision inspection systems can streamline this process, using automated technology to look for flaws and defects while meeting high standards for quality control.

Understanding the principles of vision inspection systems can help you determine whether this technology is right for your manufacturing procedures.

What Is a Vision Inspection System?

A vision inspection system, also called a machine vision system, automates the process of visually assessing your products at the end of the production line. These systems use optic lenses, sensors, and artificial intelligence technology to detect flaws, defects, and irregularities in your products.

Essentially, vision inspection systems compare manufactured products to images of what the product should look like, identifying discrepancies between the two. However, their capabilities expand beyond basic comparisons, completing tasks like:

  • Evaluating package integrity
  • Counting items to verify quantity
  • Assessing the position of a product to determine proper label placement
  • Measuring microscopic dimensions

Vision inspection systems do not replace human inspections, but they can work as an adjunct to human quality control measures, saving time and improving product quality.

What Are the Key Principles Behind a Vision Inspection System?

Vision inspection systems use a multi-step process to take images of products, compare them to sample images, and make decisions about their quality and compliance. These are the main principles of vision inspection systems.

Image Acquisition and Lighting

Machine vision systems feature optic lenses that capture images of products as they pass through the inspection line. These systems typically take photos with one of two processes:

  • Area scanning, which takes a single image of the product that is the same number of pixels as the target image
  • Line scanning, which captures multiple pictures of the product and then builds them into a single image pixel by pixel

Line scanning works best for moving assembly lines, as it prevents blurry pictures and keeps the assembly line moving during the inspection process.

Vision inspection systems need adequate lighting to take high-resolution images of the products. If the lighting in the manufacturing facility is insufficient, you can choose inspection systems that have illumination features to ensure proper lighting in each photo.

Image Processing

Machine vision systems take the images they capture, separate them into pixels or smaller visual components, and analyze them for discrepancies. While these systems work very efficiently and uniformly, small differences between photos could occur. Processing the images allows the inspection system to make direct comparisons across data points, creating a high-speed inspection process.

Feature Extraction and Pattern Recognition

After processing the image, the vision inspection system looks for patterns to indicate that the product passes or fails inspection criteria. You can program your vision inspection systems to look for specific, minute features unique to your products, such as:

  • Object position
  • Volume of ingredients
  • Quantity of components
  • Dimensions
  • Surface scratches

Defect Detection and Decision Making

After extracting the features that make up your product, the inspection system can identify defects, flaws, and any other discrepancies that exist between the product and the target image. Then, using artificial intelligence and programmed algorithms, the system can make a decision about whether that product passes or fails the inspection.

Vision inspection systems often have a low tolerance for discrepancies. Even slight differences could lead the system to flag the product, alerting a human employee to take a look. However, you can also prevent false alarms by overriding common discrepancies that don’t indicate a quality issue.

Integration and Feedback

High-quality vision inspection systems use machine learning to adapt their processes and improve their outcomes. By providing feedback, you will help the machine learn exactly what types of discrepancies to look for.

Factors Influencing the Effectiveness of Vision Inspection Systems

cookies and foil packaging

Not all vision inspection systems have the same capabilities. Working with a reputable engineering company can help you source a customized, robust, state-of-the-art inspection system that meets the highest standards for precision and performance.

Engineers take all of the following factors into consideration when designing inspection systems.

Lighting Conditions

The optical lenses within vision inspection systems depend on good lighting conditions to take high-resolution, detailed images of your products. Many manufacturing facilities don’t have the proper lighting to facilitate high-quality inspection images. Your developer will recommend lighting improvements within your facility or include flash settings in your machine vision system, ensuring adequate lighting conditions for photo capture.

Surface Reflectivity and Texture

The texture and reflectivity of your products can impact the quality of the inspection images. If your products use reflective materials, you need to approach lighting strategically to reduce glare during image capture. Your engineer can program the image settings in your inspection systems to account for any textural issues that arise.

Camera Resolution and Speed

The best vision inspection systems use high-resolution, high-speed cameras that take detailed images of your products as they pass through the production line. The camera resolution within your system can significantly impact its ability to identify minute flaws and defects.

Environmental Factors

Environmental factors, like dust and debris, can affect the accuracy of vision inspection systems. A machine vision system may pick up a speck of dust on a product and label it a flaw or defect. Your systems engineer may recommend making changes to your manufacturing environment to reduce the risk of contaminants impacting your inspection.

Where Are Vision Inspection Systems Commonly Applied?

employee working on food packaging line

Vision inspection systems have a range of uses aside from looking for flaws. The principles of vision inspection systems allow for all of the following types of tasks.

Defect Detection

Many manufacturers use vision inspection systems primarily to detect imperfections in their products. These factory automation machines can catch visual defects faster and often more accurately than human employees. They can identify even minuscule differences in products that could indicate quality issues.

Measurement and Metrology

Machine vision systems can also detect the volume or dimensions of a product. This feature is helpful for pharmaceutical manufacturing, in which every vial must contain a precise measure of medication.

Packaging Inspection

Vision inspection systems at the end of your production line can assess product packaging, looking for flaws like improper seals, misshapen packaging, insufficient void fill, and more.

Assembly Verification

Finally, these systems can verify accurate assembly, identifying potential malfunctions with other parts of your assembly line.

How Can Vision Inspection Systems Be Integrated With Other Systems?

Your manufacturing business can integrate vision inspection systems with other steps in your production line, creating a more efficient, cost-effective, and reliable manufacturing process overall.

Robotics and Automation

Automation equipment can streamline many aspects of production, like assembling parts of the product, packing the product, transferring it to pallets, and more. Accompanying this automation with a vision inspection system further streamlines your manufacturing process, allowing you to move human workers to more complex positions.

Quality Management Systems

Vision inspection systems should be just one element in a multi-step quality control process. Many businesses use machine vision systems as an adjunct to human inspections, almost entirely eliminating the potential for errors during inspections. Others use vision inspection systems as a first step and maintain a low threshold for flagging errors; flagged products then move to a human worker for further inspection, while passable products move down the production line.

Data Analysis Tools

Vision inspection systems capture valuable data about the dimensions, volume, surface appearance, and position of your manufactured products, allowing you to identify areas for improvement.

Challenges and Limitations of Vision Inspection Systems

owners of food factory planning and budgeting

Vision inspection systems aren’t completely foolproof, which is why they cannot entirely replace human inspections. Understanding the limitations within the principles of vision inspection technology can help you know how to optimally integrate it into your production line.

Complexity of Inspection Tasks

Some product defects are more visually noticeable than others. Vision inspection systems may struggle to identify very minor defects or complete more complex inspection tasks. While some systems can identify microscopic differences, their accuracy within these minute inspections may be lower.

Variability in Product Appearance

Depending on the types of products you manufacture, visual differences may be common and be no cause for concern. Other types of inspection systems, such as ones that measure weight, may be more helpful in your industry.

Cost and Implementation Complexity

Adding new machinery to your production line always requires careful planning, budgeting, and strategizing.

Discover Vision Inspection Systems From TDI Packsys

The principles of vision inspection systems could make these machines highly valuable in your manufacturing processes. At TDI Packsys, we supply E2M vision systems that provide 100% quality control for bottled, canned, and jarred products. These industry-leading systems meet the highest standards for durability, flexibility, and innovation.

Allow us to recommend the artificial vision equipment that can produce the greatest value for your company. To learn more about our vision inspection systems, contact TDI Packsys today at 877-834-6750.

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