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Annealing - laser marking procedure | TRUMPF
TRUMPF annealing application

Annealing: using the laser to apply long-lasting markings to metal

Annealing is an established method for applying long-lasting markings to steel and metals. This is due to the fact that these materials show annealing colors when heated with a laser. These colors depend greatly on the temperature at which the metal is heated. This is caused by an oxide film being generated on the surface during annealing with properties which determine the color impression.

The main advantage of annealing: the surface remains completely intact; the marking is easily legible, long-lasting and resistant to abrasion. Annealing is ideal wherever a precision fit must be maintained or material bulging is prohibited. This is why this procedure is ideal for consumer goods such as cooking utensils or medical products, for example.

This is how annealing works: the procedure for laser marking metals

TRUMPF application marking laser annealing

In order to generate annealing, the laser heats the metal locally until just before its melting point. During this process, the structure of the lattice changes; oxide is generated on the workpiece surface which is shown by the appearance of different annealing colors. These colors are temperature-stable up to approximately 200 °C. If temperatures are higher, the lattice reverts to its normal state – the mark disappears. The surface finish remains completely preserved.

In general, annealing is only possible with metals which change color under the influence of heat and oxygen, i.e. steels and titanium, but not with aluminum or non-ferrous metals. It is also not possible to mark hard metals with a dark contrast using the annealing procedure.

What are the advantages of annealing with a laser?

Gentle on the material

The material surface is hardly affected by the marking process and remains smooth even after the mark has been applied.

Simply clean

Due to the smooth surface, organic residue can hardly stick to the annealing. It is therefore particularly suitable for objects which are often cleaned.

Long-lasting legibility

Annealing remains intact and easily legible even after numerous cleaning cycles which are common for many medical products.

Established and suitable for product identification

Annealing has become established in medical technology in recent years and, along with the innovative black marking procedure using ultrashort pulse lasers, is predestined for product identification for unambiguous traceability, also in line with UDI guidelines.

Application examples for annealing

TRUMPF laser marking application

Marking consumer goods

The surface remains intact during annealing; the marking is easily legible, long-lasting and resistant to abrasion. This makes annealing perfect for marking cooking utensils.

TRUMPF laser marking annealing application

Decorative purposes

Annealing on basic commodities can be used for purely decorative purposes, such as with this cheese slicer. The mark is easy to detect even after numerous cleaning cycles.

TRUMPF laser marking annealing application - bronchoscope

Annealing for the application of lines, dots and scales

Marking lines, dots and scales must be easily legible, high-contrast and well protected from wear on objects like this bronchoscope.

TRUMPF application laser marking annealing on fittings

Product identification, product logos

Lasers create easily legible and high-contrast annealing which is ideal for applying product identifications and logos.

Design by laser marking on titanium

Creating annealing colors

By selectively setting the laser power, precise annealing colors, and therefore also colored graphics, can be created on many steels.

TRUMPF annealing application - medical products

Clean surfaces on implants

Bacteria can hardly stick to the smooth surface of annealing. This makes annealing predestined for marking implants which must remain free of any organic matter.

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Manual: Laser marking in brief

Discover the comprehensive manual "Laser marking in brief" and find out about the technical background of the processes and laser systems as well as a guideline on practical marking. Download it here.

Technology flyer: BrightLine Weld



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