Laser marking on metals

Metal is certainly the material on which the laser has its best effect and on which it is easiest to achieve diverse results. Laser marking on metals guarantees a clean and precise result. On an industrial level, laser is the most efficient technology: with laser marking, the metal component is not damaged and the result is resistant to acids and other corrosive chemicals.

Why laser marking?

Metal is the material that is most often laser-marked. The entire automotive supply chain consists mainly of metal products. Many hydraulic and medical components are also metallic. The demand that laser marking most often satisfies is that of traceability. This requires the marking of identification codes, most often QRcodes and DataMatrix. LASIT laser markers with the proprietary FlyCAD software are able to create codes with extreme versatility. The software is easy to use and allows automatic data management, connecting directly to the customer’s MES-ERP system. LASIT laser markers can also integrate a vision system for verification and grading of marked codes.

Within one station of the production chain, the traceability of its products is ensured by a high level of automation and expertise. Marking lasers perform high-contrast, high-speed processing on all types of metal, even if they have undergone post-production processing or undergone invasive work. The type of marking we are talking about is also called DPM (direct part marking) because it is done directly on the component without labels or plates.

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Lasers for Metal Marking

The most suitable laser technology for laser marking of metals is the fiber laser. It is ideal for laser marking, micromachining and cutting of all metals and alloys. It is also suitable for painted metals and metals with surface treatments such as anodised aluminium. The fiber laser can be used in its standard version as well as in its MOPA and Picosecond versions, which allow certain more specific results to be obtained on different types of metal. Moreover, compared to other stamping and writing technologies, laser marking is the most prevalent in the industrial world.

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The MOPA laser can make coloured marks on steel and black marks on anodised aluminium. The ability to control its parameters with greater agility makes it a more versatile laser and ideal for those seeking aesthetic markings of a certain type. Laser marking is subject to less corrosion (due to the limited heat input). The edges of the laser engraving show fewer burn marks.

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The Picosecond laser is a laser that allows impalpable, non-changing marks on metal. This makes it the most suitable laser for medical work. The smaller spot concentrates the energy in one spot, resulting in higher quality. It is also the first choice when it comes to applications that undergo post-marking treatments, such as citric or nitric passivation cycles.

Discover our fiber lasers

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FiberFly

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MOPA Laser

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FlyPico

Marking processes on metal

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Annealing

With annealing, laser marking oxidises the surface of metals by heating them locally. The oxide layer is usually black but its shade depends on the temperature of the heated layer. In blackening, the surface of the material remains uniform because marking does not involve removal but heating. The colour reaches a depth of 20 to 30 µm.
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Surface laser marking

With this process, laser markings of a few hundredths of a millimetre in depth are made. Less energy converges in the laser beam than in laser engraving and, as it has to dig less deep, the operation is faster. Once in contact with the material, the marking melts it superficially, changing its roughness.
Incisionesuperficiale Laser marking on metals

Pre-blast laser engraving

Sandblasting and shot peening are very frequent processes on cast components, necessary in the machining cycle but they also very invasive. One of the risks of these processes relates to traceability, i.e., the compromise (and therefore readability) of the DataMatrix code. At LASIT, we have developed a strategy to prevent the DataMatrix code from becoming unreadable after the various processes.

MarcaturaBiancaLasit Laser marking on metals

White laser marking

In contrast to oxidation, to obtain a white marking the laser focuses on the material and removes a part of it. The surface of the metal thus becomes uneven and a reflective effect is achieved. Light reflecting off the dark component causes the marking to be visible.
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Paint removal

Lasers are capable of precisely removing and carbonising the layers of paint that coat components, in order to ensure traceability with a code or to achieve an aesthetic effect, such as marking a logo. The laser beam removes paint from the surface of the material partially or completely depending on the desired effect.
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Engraving

While laser marking creates grooves, in engraving the laser is powerful enough to vaporize the material in a few milliseconds, creating permanent marking marks. The engraving has a higher degree of resistance. It is therefore recommended when the marked component undergoes post-process stress (such as sandblasting for die castings).

Metals on which laser marking is performed

Laser marking on stainless steel

Laser marking on steel and stainless steel is used both as a traceability method and for aesthetic marking of logos and graphics. Lasers guarantee indelible marks that do not lose quality over time. Either using a traditional fiber laser or with its variants MOPA and Picosecond, achieving high-contrast markings is guaranteed. Laser marking on steel is also a tool that is increasingly used in the world of household appliances and of taps and fittings. This is because in recent years it has achieved very high levels of aesthetic precision and high resistance to corrosive agents, to which these products are exposed. Lasers are able to meet the quality requirements of automotive productivity requirement, of hydraulics, of the aesthetics of home appliances and the safety of the medical industry.
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Marking 2D Codes on Metals

In the industrial world, laser marking is mainly used for traceability. As a result, laser markers are intended for a production line where a DMC or serial number takes center stage.

For both integration lasers and industrial automations, LASIT has gained great experience in the marking and verification of 2D codes on all types of metal, in particular for Automotive, Hydraulics (nameplates), Household Appliances and Taps, Smelters, Medical components.

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Marking or engraving? What is the difference?

All laser marking or engraving methods have one thing in common: the laser beam is pulsed and releases energy at specific intervals. What changes are the speed and spacing, which determine the distance between one pulse and another.
In marking, the laser melts the material through heat and changes its shape to imprint a permanent code or mark. Laser engraving, on the other hand, vaporises the material. To do this, the laser must be powerful enough to vaporise the material in a few milliseconds and the material to be marked must have a suitable sublimation temperature. The laser beam penetrates deeper into the surface and removes the upper layers by sublimating them, i.e. through a direct transition from the solid to the gaseous state. This difference is not obvious to many, but for laser marking experts it is important.

Engraving takes longer than marking because it penetrates deeper.
Marking melts the material by changing its roughness, engraving sublimates the material by creating grooves.
Laser engraving is suitable for components with a higher risk of wear due to environmental conditions or post-engraving processes.

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