Tracking processes and products
Steve Scheiber, Contributing Technical Editor -- Test & Measurement World, 11/1/2004
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| Data Matrix codes can be created in a variety of sizes. The code above could also be created in a image that is small enough to fit on the head of a pin. |
You could track each product through its unique serial number, but having operators type serial numbers during production is a slow, error-prone process. Bar codes offer a significant step in the right direction: Inputting the number with a simple swipe from a handheld reader increases the quality and reliability of the resulting data.
Yet, conventional bar codes also have their limitations. Such bar codes are inherently one-dimensional—they present their information in analog form as bars and spaces of varying widths, typically on a label.
According to John Agapakis, senior VP for RVSI Acuity CiMatrix, a maker of machine-vision products in Nashua, NH, a scanner can reliably read a conventional bar code only if the code consists of a precise, high-contrast image. Any blips or breaks in the image can introduce errors, and labels can come off at any time,reducing their usefulness for cradle-to-grave monitoring.
Enter Data MatrixInstead, Agapakis suggests a two-dimensional Data Matix image (Ref. 1), which encodes information digitally
Agapakis identifies four basic elements that must be part of any Data Matrix implementation: marking, verification, reading, and communication.
Probably the most common marking technique for both electronics and semiconductor applications is laser etching. RVSI's Symbology Research Center in Huntsville, AL, is working with NASA under the Space Technology Transfer Act to develop new marking solutions—methods and parameters appropriate for various applications, surface preparations, operating environments, and so on.
A verifier (rather than a reader) ensures that a mark's quality is sufficient to be read accurately. Verification includes detecting process changes and adjusting the marking step before it produces any unreadable marks.
Machine-vision technology is used to read Data Matrix codes. Early readers consisted of discrete lights, cameras, lenses, image processors, and so on. Today's readers more closely resemble the bar-code readers that they replace.
Finally, successful implementation requires accurate communication of the data. Readers must connect directly to factory floor networks and interface with high-level data-management software.
The need to track products precisely will not go away. Data Matrix codes offer one solution for tracking a product throughout its life cycle.
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