Data Matrix Marking Methods
November 9, 2007
When selecting the best way to create 2D machine-readable Data Matrix codes, engineers have a number of options to choose from. In many ways, the best approach depends on the type of material being marked. However, it’s also important to look at the big picture.
Manufacturers working in sensitive industries like the medical sector, for example, will often have little choice in the matter, because marking technologies are often specified by regulatory agencies like the FDA. Similarly, a marking method may need to accommodate a particular process requirement, such as cycle time or clean room standards.
When marking glass or creating clean, high-resolution marks on metal or plastic, many engineers select the laser-etch approach. This marking method is more expensive, but is extremely reliable and requires neither consumables nor the periodic replacement of worn parts. Laser markers create clean, square-shaped, low-contrast cells on metal, and medium-contrast cells on glass.
At the other end of the cost spectrum are ink-jet printers. Unlike laser markers, ink jets create round dot-like cells, and require the use of a consumable. Inked symbols are also not considered to be “permanent” in many industries: for example, in the automotive industry where a mark will be expected to endure years of often dirty or greasy conditions.
Between these two extremes are dot-peen markers, in which a pneumatic or electromagnetic driver is used to create the code pattern with the help of a hardened-carbide or diamond-tipped stylus. This approach can be used on a variety of surfaces, including steel, plastics and glass, and requires no consumables, although the styli need to be periodically replaced. Like laser markers, dot-peen markers create permanent marks-either round or square depending on the stylus-and are well suited to use in an automated environment. On the downside, dot-peen marks are often low contrast. This can result in reading problems down the line, unless good contrast can be created in the images with correct illumination.
Finally, there is electro-chemical etching, which requires the use of a low-voltage current and stencil. In contrast to the other three technologies, this technique, does not lend itself to high-volume production. However, it creates precise marks and does not weaken or distort the metal substrate, making it a good choice when marking fragile and thin-walled parts. For this reason, it is sometimes used in the semiconductor industry.