Inspection System Specifications Explained

    Evaluating inspection systems can be a difficult task whether you’re purchasing your first or fifth. This month we’ll break down some of the key specifications of inspection systems so you will know what to look for based on your needs. Before going over some of the basic specifications you’ll usually see when shopping for an inspection system, here’s a quick run-down on how most inspection systems work.

    Inspection Systems typically consist of a camera and lighting assembly, timing circutry, and a computer with user interface. To control lighting, the inspection camera and lighting are contained within a single case that is installed on the press, rewinder or other machine. The light provides bright, true color light that allows the camera to capture the most accurate image possible from the web or substrate. Once that image is captured, it is sent to the inspection software for processing. From here, many things can happen depending on the inspection systems capabilities and the specific needs of the job. For the most common type of inspection, the image is compared to the master. If there are defects, they can be marked, the defective image can be stored, and the operator can be alerted. This can be combined with other capabilities such as bar code verification, sequential data verification, dimensional gauging, braille inspection, and more.

    Here, we will define some of the most common technical specifications and features of inspection systems.

    Strobes and Types of Lighting

    LED:LED lighting is more expensive than Xenon bulbs, but they last longer (8 to 10 years). LED lights provide consistent lighting over the entire life of the bulb.

    Xenon:Xenon bulbs have a lower start-up cost than LED bulbs, but also have a shorter life (6 months – 1 year). Light quality can degrade over time, unlike LED lighting, and can require re-calibration.

    PC Industries offers the best quality lighting based on each application’s requirements.

    Camera and Capture Style

    Area Scan:Area scan cameras capture rectangular images, similar to how the common point-and-shoot cameras work.

    • Larger footprint (camera box size)
    • Used for smaller fields of view
    • Lower resolution
    • Slower speeds
    • Can be positioned to focus only on areas of interest

    Line Scan:Line scan work similar to a flat-bed scanner. The cameras take continuous, one pixel captures of the entire web width under consistent lighting.

    • Smaller footprint (camera box size)
    • Larger fields of view
    • Long repeat lengths
    • High resolution
    • Higher Speed

    PC Industries offers a wide variety of camera configurations that can be configured to the ideal settings for each installation. Camera specification and performance is detailed in each quote provided by PC Industries.

    Cameras and Image Quality

    Resolution:How many pixels wide by how many pixels tall the captured image is. A higher resolution camera can capture an image in more detail to detect smaller defects.

    Field of View:Field of View: The Field of View is the physical dimensions that a camera can capture. It is usually indicated as width x height, and is given in inches or millimeters. The field of view needed for an inspection application can be based off the area of interest or the width of the substrate being inspected.

    Minimum Defect Size:The minimum defect size that an inspection system can detect is determined by the field of view and the resolution. A larger resolution or smaller field of view means that a smaller defect can be detected.

    PC Industries offers a wide variety of camera configurations that can be configured to the ideal settings for each installation. Camera specification and performance is detailed in each quote provided by PC Industries.

    Processing

    Variable Data Inspection:For applications with sequential numbers, such as serial numbers and bar codes, variable data inspection allows the system to read and verify the values of these numbers. This capability includes:
    OCR: Optical data recognition- ecognizes random characters
    OCV: Optical character verification- Verifies characters against expected data.

    PC Industries offers variable data inspection and verification. It can verify sequential, as well as variable, which compares the sample to a list of acceptable values. The operator is alerted if the system finds missing or incorrect characters, or if they are below a given quality threshold.

    Dimensional Gauging: This feature is used to track the relationship between features on the printed sample.

    PC Industries offers dimensional gauging that can be set to track any print or die feature on a run.

    Bar Code Inspection: There are several different levels of bar code inspection available. First, bar code image is compared to the master image to check for defects. Second is bar code decoding, where the system verifies that the bar code can be read as well as make sure that it matches the master. Finally, bar code grading scores the quality of the bar code to ANSI/ISO standards.

    PC Industries offers system configurations that can inspect to any of these levels.

    Alerts: Inspection systems are capable of informing the operator when there is a defect, or when a job begins to run out of spec. There are several interfaces for these alerts. The inspection system can sound a horn, activate a light, or even stop a rewinder or machine when a defect is detected.

    PC Industries offers programmable outputs so these alerts can be adjusted to your needs.

    Post-Comparison and Defect Logging: Another important aspect to consider is what the system does with a defective image once a defect has been detected. One option is to stop the press or rewinder so the defect can be corrected or removed. Another option is to store the location of a defect for later recall on an audit rewinder, allowing the press to run continuously.

    PC Industries systems can start inspecting from zero speed, and offer many options for handling defects. 

Defect Roll Mapping records the position and image for all defects found during inspection. This data of defect images and locations can then be accessed by a secondary interface on a rewinder to automatically queue up these defects for correction.

    Audit Trail: For pharmaceutical applications and others that have stricter security requirements, an audit trail is required to help reduce company liability. The audit trail comes in many forms, but is typically in FDA 21 CFR Part 11 compliance, which requires a secure login.

    PC Industries’ systems can produce a secure report for each run, which includes defect images, project settings, and a log of operator action. Secure accounts can also be set up with operator and administrator level access.

    Defect Flagging: This option marks the web or substrate to highlight the location of a defect.

    PC Industries offers a number of automatic flagging or labeling methods, including the FlagRM.

     
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