The 5 factors to consider when laser marking metals

It is a quest for continuous improvement of the quality and contrast of laser marks whether you are new to laser marking or already have significant experience with the technology. As metals are ubiquitous in pretty much everything we touch in our daily lives, from electronic gadgets to sophisticated medical equipment, laser marking metals are of particular importance.

Marking with lasers is a non-contact method for permanently marking metals, where the depth of the cut is controlled and even automated. Laser marking metals are convenient in that they can be used with almost any vector software, such as CAD or Illustrator, to mark patterns. Laser marking metals, like all machining techniques, have some important factors to consider, and that’s exactly what we’ll cover in this post. Let’s take a look at 5 things to consider when laser marking metals.

Material Properties:

Any laser marking application should take into account the material being marked. In other words, materials have different absorption spectra, which means they react differently to different wavelengths. 

In deciding what material to use with what laser source, this must be considered. You should also consider the melting point and the material’s response to heat. It is also important to consider the material’s hardness. Due to its lower melting temperature, aluminum is a much softer metal and will take less time to laser mark than steel.

Type of the Laser:

Laser marking metals can be done with CW lasers as well as pulsed lasers. On the other hand, pulsed fiber lasers are more commonly used since they can deliver a higher intensity beam without overheating the sample. The forms of lasers maximum generally used for laser marking include carbon dioxide, ytterbium-doped fibers, UV, and green and neodymium vanadate lasers (How to Laser).

The CO2 laser is less commonly used for metal and more commonly used for wood, glass, and plastic. Again, green lasers are primarily used to process plastics and glasses rather than metals. Metals are commonly marked with fiber lasers, and they’re appropriate for a wide variety of metals, ranging from steel to copper. Marking metals generally requires lasers with a power of at least 50 Watts. Compared to lasers of similar average power, fiber lasers can produce better beam quality. Laser marking is controlled by the beam quality, which is responsible for the beam’s spot size.

Choosing the Right Laser Marking Method:

There are multiple methods for laser marking metals that produce different types of marks. When selecting the right method for a specific application, durability and time are just some of the factors to consider. Here are some options:

Engraving by laser:

The method sublimes the metal. As a result of the laser’s heat, the metal goes directly from solid state to the gas state. Due to their very deep marking, laser engraving creates very resistant markings in comparison with laser marking methods. Laser engraving normally cuts between 0.0001″ and 0.005″ deep. Laser engraving provides permanent marks that are very useful in applications requiring part traceability.

The laser etching process:

The laser etching process melts the metal almost instantly. It produces highly contrasting marks. Laser engraving is more permanent than laser etching, and etching typically leaves a shallower mark than engraving-less than 0.0001″. Since the marks created by etching are shallower, they are also suitable for thinner metal sheets that require less permanent marking.

Annealing with lasers:

With this process, specific metals, namely steel, titanium, and stainless steel, can be marked with colored markings. As a result of this method, the material is not actually removed, but rather a chemical reaction takes place beneath the material’s surface, making it ideal for surfaces that cannot withstand damage. A laser beam slowly heats the metal, changing its lattice structure. Metals oxidize and change color when cooled. When incident light strikes annealed metals, some of it is reflected off the oxide layer and some is absorbed. The light absorbed by the oxide layer is then absorbed or reflected back. The thicker the oxide layer, the darker the metallic color.

Cost:

In determining whether to purchase a laser marking setup or just have the services performed by another party. One must decide whether one is a better investment than the other. This will depend on the number of products that require marking and/or the frequency with which the laser marking setup is used. You should also consider the cost of the material and the time it takes to mark the product.