Creating a black mark on anodised aluminium

In this guide we show you how to use a MOPA laser to create black markings on anodised aluminium.

Black laser marking on anodized aluminum

Creating high-quality dark markings on anodised aluminium

Anodised aluminium is an excellent material for laser processing, and can be quickly processed. The anodised layer is removed by the laser and a white mark is created. This is particularly well suited for coloured anodised coatings. In the case of natural anodised aluminium, however, this marking is not clearly visible, and black marking is also of significantly higher quality. With a MOPA laser source, natural anodised aluminium can be laser-marked in various grey tones up to a rich black. This process can be used to mark high-quality smartphones, among other laser marking applications.

Short pulse durations ensure the desired result.

With a MOPA laser source, you can set very short pulse durations. This is the secret to creating black marks on anodised aluminium, as the short pulse durations do not damage the surface of the material. The anodised layer is not removed, simply repainted. Whilst the process of black marking is completely different from the production of tempering colours on stainless steel, a comparable result is created. You can set the filling line distance to adjust in a wide range of various shades of grey up to black: The smaller the distance, the darker the laser marking result.

How you set the correct parameters:

To create a black mark on anodised aluminium, you need a 20 watt MOPA laser source. 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 grey tones	1

The following points need to be considered:

It is important to remember that the anodised layers can be very different. Always use the engraving page for black marking. If you 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 anodised aluminium from webshop.

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