Processes Laser Annealing

Laser Annealing

Annealing marking is when an oxide layer is created on ferrous metals (iron, steel, high-grade steel) and titanium through localized heating.

Generally, the oxide layer is black, but it can also have other annealing colors (such as yellow, red and green). The color depends on the temperature of the heated layers.

The material surface remains even during annealing because nothing is removed from it; the color change is achieved through localized material heating only.

The heat usually penetrates 20 to 30 µm deep in the metal surface. This makes the marking non-abrasive and ensures that it can be removed by re-heating (min 700°C for ferrous metals).

Suitable laser systems:

Laser marking of stainless steel in the medical industry

There is much more to marking medical devices than just complying with regulations. Whether manufacturers have to comply with global standards and apply all ID marks reliably with repeat accuracy or whether they have to ensure product quality – all medical products have to be marked properly in the first place. To ensure correct part identification, absolutely traceable marks are indispensable. Laser marking is the ideal method to create these marks and at the same time offers an increase in production efficiency and decrease in costly product scrap.

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Ball bearings made of steel with black marking

Ball bearing made of typical machining steel (sulfur-free steel) with black annealing marking.

Color laser marking on stainless steel

Annealing marking allows the creation of various colors and is even appropriate for giving substrates different designs.

In medical device production, stainless steel and titanium are often in use. When even surfaces are required in order to prevent germs from penetrating, annealing is a good marking solution, because the local heating process results in color change instead of material removal. Moreover these marks are highly resistant.

The stainless steel shown here has been electro polished before marking. Different surface treatments are possible as well, like brushing or micro abrasive blasting.

Delivery pipe for a natural gas car

Annealing marking on a delivery pipe used in vehicles powered by natural gas.

Black marking on aluminum

Laser causes local heating of aluminum surfaces and thus oxidation. This process is called black marking, its physical or chemical effects are still unknown. The marking results have proven to be rich in contrast and wear-resistant.

Black marking on aluminum is often used for inscriptions on smartphones or notebooks.

Best suitable for black marking on aluminum are laser systems from the FOBA Y-Series. Using the short pulsed FOBA Y.0201 ensures that there is no damage to the aluminum surface at all.