The 2-D Data Matrix barcode has numerous advantages over its one-dimensional counterpart, the linear barcode. Generally speaking, Data Matrix can hold substantially more data than a linear barcode -- as much as 100 times the information. Additionally, a Data Matrix code can be read in any direction, and it can still be read even if portions are damaged.
Perhaps it's these advantages that led the Department of Defense to choose Data Matrix for its Item Unique Identification, or IUID, program. IUID is used to track DoD assets throughout their life cycle, from "cradle to grave." Details of the IUID program and marking requirements are spelled out in MIL-STD-130.
Equipment suppliers who contract with the DoD are expected to comply with labeling requirements contained in MIL-STD-130. This can be stressful at times, as large contracts may hinge on following the potentially complex specifications. First of all are questions about how large the Data Matrix must be and where it should be placed on the equipment. The DoD contracting office should be able to provide guidance in this regard. Working with an experienced, knowledgeable systems integrator is also beneficial.
Then there is the central issue: Can the Data Matrix be reliably read? This is where the IUID verification process comes into play. Just checking the label with one's own IUID reader isn't enough, as attempts to read the label will be made over many years, using many varieties of scanners and in different environments. Parameters considered in the IUID verification process may include the consistency of light and dark elements, whether the symbol stays within its designated space, whether the symbol is skewed on an angle, whether the image has bled, whether dots are round or oval, and whether there's a good contrast between light and dark elements, among other factors.
Why verify?
The reasons to verify Data Matrix labels are many. Verification helps ensure you are in compliance with MIL-STD-130 requirements; some contracts may require label verification. Making sure symbols are readable will reduce costs from returned products, and prevent potential cancelation of contracts. In some cases, defective labels may result in fines. Good quality labels contribute to customer satisfaction.
One way to verify 2-D Data Matrix symbols is by installing an IUID verification station just after the labeling station on the production line. That way, if there's a problem with the labeling process, it will be noticed and can be corrected right away, before scores of bad labels are produced. Software is available that scrutinizes the Data Matrix, grading it on the parameters listed above.
