In the previous article about data matrix codes (DMCs) you learned some basics. This article addresses questions which you will come across in your daily work with marking DMCs sooner or later:
- How can you optimize the DMC to increase its readability?
- How can you decrease the marking time for a DMC?
- How can you avoid that DMCs are incorrectly marked?
How can you optimize the DMC to increase its readability?
There are several factors that influence the readability of laser marked DMCs, especially the contrast between the “black” and “white” cells of the DMC. This contrast can appear particularly low, where the surface of the marking area of the DMC is rough. In such cases, the marked DMC often looks a little bit fuzzy, not as crisp as it should be for good readability with a scanner or camera.
In such situation, one remedy could be smoothening the background first and then mark the DMC on the flat surface. Alternatively, and more time efficient is the ultra high contrast or “black/white” marking with fiber laser: First, the black cells are marked as usual, and then an inverted DMC is marked on the same place with laser parameters, which result in a “white” marking. That typically gives you a DMC with a nice cell contrast, as you can see below (the left code), entailing much better machine readability. The optimized ultra high contrast marking provides optimal readability, even on complex surface structures.
How can you decrease the marking time for a DMC?
Sometimes your available production cycle time forces you to look for possibilities to decrease the marking time for your DMC as much as possible. The natural first approach would be to look for other laser parameter combinations (i.e. the mix of marking speed, frequency repetition and power) that allow to mark the requested DMC with still acceptable appearance.
However, if that still does not lead to the required marking time, you might want to think of using a DMC which consists of dots instead of squares. The following illustration shows two DMCs with the same content, yet the left one with “standard” squares, while the right one comes with dots.
How can you avoid that DMCs are incorrectly marked?
Complete traceability is more than having a DMC with a high contrast. It is also important that the right data are marked on the right product on the right position. With a laser-integrated vision system the marking can be read and validated. Furthermore, an integrated vision system that provides a closed-loop marking process like HELP (Holistic Enhanced Laser Process) offers validation steps prior to laser marking to avoid that parts are incorrectly marked.