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Blog on laser marking & traceability, laser cleaning and safety standards

Three Laser Marking Technologies for Your unique Applications

For most companies, every capital investment is a huge decision that needs to be reflected upon. If economic uncertainties requires a thorough analysis of the market before proceeding to such investment, there's also other areas to take into account when evaluation the risk of a capital expenditure.

For example, the available funds to improve one's company equipment might be scarce, but the needs usually aren't. Hence, competition between different projects may occur, and there's a need for some qualitative and quantitave arguments to make a choice. Be it the gain in productivity or the impact of this new equipment on your workers. But before even delving into these specific points, it is obviously important to make sure the next machine you acquire is the one that suits your specific needs. This is especially true for laser marking systems, as the initial costs can be high.

Laser marking technology can be hard to understand for the untrained eye; let alone trying to appreciate the differences between available laser technologies.

To help with understanding the purpose of each technology, I'll explain briefly how different technologies help achieve different results. The bulk of this article will then follow with an explanation of the advantages and disadvantages of: C02, solid-state, and fiber laser, marking technologies.

Is There Such a Thing as a Do It All Laser Marking Solution?

The short answer is no, or at least, not yet.

Laser marking is possible because of fundamental principles that are at the heart of light-matter interaction. Every material, due to their atomic properties, reacts differently to incident light. The amount of power absorbed, which is what makes the marking, is highly dependent on the wavelength, and it differs from material to material.

Moreover, different laser marking applications don’t have the same requirements in terms of the power and time during which the material is subjected to the laser light. For example, annealing needs the surface of the material to be heated in order to make a color contrast. This is typically done with low peak power, but for a longer exposure time. On the contrary, engraving requires high peak power for short periods of time in order to vaporize a thin layer to create the markings.

Unfortunately, there is no one do it all laser marking system that can excel in every situation. Some lasers are better adapted to specific types of marking. Because of all this, one needs to ask these two questions in order to make an informed choice about the type of marking solution which is needed:

1- What kinds of materials do I want to mark?

Different types of lasers, currently on the market, make it possible to mark metal surfaces, as well as organic material such as leather or wood. Plastics and rubber are also eligible materials for laser marking.

2- How do I want to mark the specimen?

There are three main methods: Engraving, etching and annealing. (Take a look at this earlier blog entry for more information about these methods).

Ultimately, the choice of a laser marking system will depend on your answers to these questions. Keep them in mind and let them guide you through your analyses of available laser technologies, covering which ones best meet your needs and what are their most common drawbacks.

The Three Main Laser Marking Technology on The Market

CO2 Laser Marker

Laserax CO2 Laser, LXM Series

 

Fig. 1 - Laserax LXM Laser Series

Gas lasers work, as suggested by their name, with gas as a light amplification medium. The most common gas laser, at least in the marking and cutting industry, is the CO2 laser, which is pumped by an electrical discharge. Having a long history, this laser was the go-to choice in many industries before the advent of other laser marking technologies. It emits at wavelengths near 10.6 μm, in the mid-infrared. Since the heat doesn’t increase in the gas medium, the CO2 laser can produce higher power output averages. The wavelength at which CO2 lasers emit are more readily absorbed by organic materials compared to the operating wavelength of other common laser marking solutions. There is no need for external pump diodes with a CO2 laser marking system. A typical MTBF (Mean Time Between Failures) of 20,000 hours is possible, as with the Laserax LXM series for example.

 Pros

  • The best marking solution to efficiently mark organic materials such as wood, leather and cardboard
  • Has a long history in the laser marking industry
  • The most affordable solution
  • High beam quality provides crisp and clean marking edges
  • Fewer replaceable parts

Cons

  • The higher wavelength provides low power density on the surface to be marked, thus a larger beam diameter is required. This has two consequences:
  • There's not enough power density to mark metal surfaces, but annealing can sometimes be achieved on anodized aluminium or painted metal
  • The larger beam diameter means a lower resolution and therefore can't efficiently mark small details
  • Common CO2 laser used for marking come on a XY positioning table. This however is not the case with the Laserax LXM series, which comes as a modular platform that can be integrated into most production lines

Solid-State Laser Marker

Solid-state lasers use a crystal as an amplification medium and are usually pumped with a laser diode or discharge lamp. Emitting at around 1μm, the most common crystals used in marking applications are the Nd:YAG and the Vanadate crystal. The crystal medium generates a high concentration of atoms which create light amplification. These lasers can have high peak power. However, as the crystal heats up rapidly, the average power must be significantly lower than other types of lasers. This means the pulses can have a high repetition rate, for a small period.

Pros

  • Better beam quality means it can be focused to a small diameter, offering a high power density and high resolution on the surface to be marked
  • Faster marking than CO2 laser markers because their higher power density is absorbed by the material
  • Fast repetition rate makes this system well suited for engraving applications.
  • Possibility to double the pulse frequency of the output beam in order to mark gold or other metals which strongly reflect infrared wavelengths

Cons

  • Initial cost is higher than that of CO2 lasers, but similar to fiber laser systems
  • High maintenance costs as the mirrors and the pump (laser diode or discharge lamp) need to be replaced periodically
  • The crystal itself can deteriorate and this can reduce its output power
  • Not suited for annealing applications, as their small pulse duration and high peak power would vaporise the metal instead of heating it
  • Doesn't work well on organic materials

Fiber laser marker

Laserax Fiber Laser - LXQ Series

fig. 2. Laserax LXQ Laser Series
Fiber lasers are similar to solid-state lasers except that they use rare earth elements introduced in the fiber optic core as their gain medium. However, instead of consisting of a crystal between two mirrors, the gain happens inside an optical fiber. This protects and guides the beam until it is ready to be focused on the surface to be marked. Usually made of Erbium or Ytterbium, Fiber lasers have a wide spectrum of emission.

Fiber lasers are similar to solid-state lasers except that they use rare earth elements introduced in the fiber optic core as their gain medium. However, instead of consisting of a crystal between two mirrors, the gain happens inside an optical fiber. This protects and guides the beam until it is ready to be focused on the surface to be marked. Usually made of Erbium or Ytterbium, Fiber lasers have a wide spectrum of emission.

Pros

  • Excels at marking metal, because of their shorter wavelength and their pulsed capavb. They can also mark polymers
  • Great versatility, as the pulse duration and pulse repetition rate can be modulated to allow engraving as well as annealing
  • The Laserax LXQ 3D Vision series can do 3D marking with large tolerances for the positioning of the object using a 3D camera inside the laser head
  • Compact design, with no moving parts as the light amplification happens within the optical fiber. This makes it ideal for direct integration into a production line
  • Low maintenance marking solution as there are no replaceable parts and a MTBF of 100,000 hours for Laserax fiber lasers, LXQ series
  • Lowest operating cost as fiber lasers are some of the most efficient lasers in the marking industry

Cons

  • Can't mark organic materials such as wood or leather
  • Usually comes at a price point higher than CO2 laser markers, but similar to solid-state lasers

Finally, these three marking technologies (CO2, solid-state and fiber laser) each fulfill different needs when it comes to industrial marking. CO2 lasers are especially adapted for wood and other organic materials. Solid-state and fiber lasers, on the other hand, are better at marking metals. The fiber based systems offer the greatest versatility when it comes to the desired marking technique, because it can do both engraving and annealing, whereas solid-state lasers can only do engraving.

Understanding the different choices available in laser marking systems will make it easier to determine which system is best suited to your materials and applications. Keeping this information in mind will guide you in your analyses of available laser technologies. Should you need further information or help with your decision, you can always contact our experts.

 

Download your laser marking guide now

Posted by Arthur Perret

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