Black marking on anodized aluminium

In this article, we will teach you how to use your MOPA laser to create black markings on anodized aluminum.

High-quality dark markings on anodized aluminum

Anodized aluminium  is the ideal material for engraving with a laser because of the quick processing time, as well as the high quality of the finished product. By using a laser, the anodized top layer is removed and simultaneously a white marking is generated. This is particularly well suited for colored anodized coatings. However, when using natural anodized aluminium, these markings are not clearly visible. Because of this, black marking is considered to be of significantly higher quality. By using a MOPA laser with natural anodized aluminium, it allows the material to be marked in various tones of grey and even a rich black. This process is also used to mark high-quality smartphones, among other applications.

Short pulse durations ensure the desired result.

By using a MOPA laser, you can set very short pulse durations. This technique is the key to sucessful black marking of anodized aluminum. One of the benefits of this technique is that the short pulse durations eliminate damage to the surface of the material. The anodized layer is not removed, but just repainted. Although the process varies from the production of tempering colors on stainless steel, the end result makes for an excellent comparison. You can set the filling line distance to adjust in a wide range of various shades of gray up to black: The smaller the distance, the darker the marking gets.

This is how you set the correct parameters:

You need a 20 watt MOPA laser to mark anodized aluminum black. We recommend using the F-254 lens because it perfectly fits the spot diameter for this application. You should set the following parameters:

Power Speed Frequency Pulse duration
50% 1500 mm/s 200 kHz 8 ns
Focus Filling lines distance Passes
In focus 0.001 mm bidirectional for a rich black
0.002 - 0.005 mm bidirectional for gray tones

The following should also be considered:

Keep in mind that the anodized layers can be very different. Be sure to always use the engraving page for black marking. If you are ever in doubt and have further questions, our experts from the application laboratory will be happy to help. To ensure that the parameters we specify work, we recommend that you purchase anodized aluminum from our product range.

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