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How Does Laser Engraving Work?

authorIcon By Jerome Landry on January 13, 2020 topicIcon Laser Marking

What’s laser engraving and how does it work?

Laser engraving is a process that vaporizes materials into fumes. The laser beam acts as a chisel, incising marks by removing layers from the surface of the material. The laser must hit localized areas with massive levels of energy to generate the high heat required for vaporization.

In this article, you’ll find in-depth information on how laser engraving works.

But first here’s a short video that shows the laser engraving process in action. In this video, you’ll see the high-quality contrasts, the marking speed, and the fumes generated during the marking process.

Should You Choose Laser Engraving or Laser Etching?

To choose the right laser marking process, you should rely on three factors:

  • The marking’s resistance: its capacity to remain legible under harsh conditions
  • The laser marking speed: the marking time that prevents production bottlenecks
  • The material being marked: its compatibility with the marking method

Laser engraving technology is typically used to engrave metal workpieces that will be exposed to various types of wear or surface treatments. Metal engraving works with steel and aluminum (including anodized and die-casting aluminum).

The most outstanding feature of this process is its ability to engrave 2D codes that keep high readability rates after post-process treatments. Those treatments can include shotblasting, e-coating and heat treatments, addressing the most complex traceability issues.

But if engraving the most resistant identifiers isn’t needed, laser etching is generally preferred because it’s a high-speed method.

You can laser etch a wider variety of materials, including steel, aluminum, anodized aluminum, lead, and magnesium.

There’s also a unique method called laser annealing to mark metals like stainless steel.

From Solid to Gas: How Engraving Works

Whereas laser etching melts the material surface to change its roughness, laser engraving sublimates the material surface to create deep crevices. This means that the surface instantly absorbs enough energy to change from solid to gas without ever becoming a liquid.

To achieve sublimation, the laser engraving system must generate enough energy to allow the material’s surface to reach its vaporization temperature within milliseconds. Considering the extreme temperatures required for sublimation, laser engravers are pretty powerful tools.

Vaporization Temperature of Various Metals
Material Vaporization Temperature
Aluminum 2327°C
Copper 2595°C
Iron 3000°C
Lead 1750°C
Magnesium 1110°C
Zinc 906°C

Source: "Corrected Values for Boiling Points and Enthalpies of Vaporization of Elements in Handbooks"
Note: For metal alloys (such as steel), vaporization temperatures vary according to the alloy's composition.

 

Materials are vaporized into fumes when they reach this temperature. As a result, when you buy a laser system, it should always come equipped with a fume extraction system to protect the work environment and an air knife to protect the laser’s lens.

How Do You Engrave High-Contrast, High-Quality Marks?

If you look at the following magnified images, you can see the chaotic surface created as a result of laser engraving.

Before Laser Engraving After Laser Engraving
The bare aluminum before laser engraving, viewed using an electron microscope. The surface is rather smooth. Cells of a data matrix code engraved on an aluminum surface, viewed using an electron microscope. Part of the surface shows absorption caused by chaotic changes in roughness.

Permanent marks created by laser engraving are darker because light is trapped in deep crevices (the engraving depth can reach up to 0.5 mm).

There are two ways of creating contrast with laser engraving.

Laser engraved alphanumerical values in black only.The first (and faster) engraving method creates contrast between the bare material and the black marks that are engraved. This method is only recommended if the bare material color is pale enough to generate a high contrast.

 

 

Laser engraved data matrix code with black and white cells.The second (and longer) engraving method achieves higher quality contrasts because it etches black and white marks. With this method, the laser system uses both laser engraving (to create the black marks) and laser etching (to create the white marks).

 

 

Find a Laser Engraving Machine

If you’re looking for a laser engraving machine, this list will help you find the right laser:

  • To integrate custom solutions yourself or with an integrator, view our OEM marking systems, including multiple types of lasers for industrial applications. Our range of laser systems includes fiber lasers and CO2 lasers.
  • For turnkey automated or semi-automated laser solutions, consult our integrated laser machines page.
  • To find information specific to the metal you’ll be marking, scroll through the list of metals.
  • If you need guidance, you can always ask an expert.

More Information on Laser Marking and Engraving

Apart from etching and engraving, other laser technologies can be used to mark logos and identifiers like barcodes and serial numbers.

If you want to know what sets them apart, you may find the following posts interesting:

Jerome Landry's picture

Jerome Landry

Trained in physics and physical engineering, Jerome has been working in the high-tech industry for more than 4 years. He is currently a technical sales specialist at Laserax. He has hands-on experience with laser processes and their interaction with materials, as well as with industrial traceability standards. This allows him to guide clients toward the best laser solution.