Knowing how to choose the right laser engraver for your application is not that complicated. If you are willing to learn just the basics of fiber laser engraving, you can quickly identify what you need.
The first thing you must know is that there is no such thing as a “fiber laser engraver”. You may need a laser engraving machine for metal, but the laser you’re looking for could also be configured for laser cleaning as well as various laser marking applications.
In this article, you will find answers to the following questions:
- What Are the Types of Fiber Lasers?
- How Much Laser Power Do You Need?
- How Do You Choose a Fiber Laser Marking System?
- Why Choose a Fiber Laser for Metal Engraving?
- How Does Fiber Laser Technology Work?
Each type of fiber laser is the combination of a laser source, laser beam output, lens configuration and laser parameters. For that reason, there is a wide variety of fiber lasers that offer different benefits. Choosing the right technology is key to get optimal results.
The Laser Source
The laser source includes an optical fiber which can be doped with different rare-earth elements to generate specific wavelengths. By knowing the laser source and its wavelength, you can quickly know if a fiber laser is right for your application. Let’s look at common examples:
- Ytterbium-doped fiber lasers produce a wavelength of 1064 nm, which makes them ideal for the material processing of metals. These are the fiber lasers that Laserax uses for metal marking and cleaning applications.
- Thulium-doped fiber lasers produce a wavelength of 1940 nm and can be used for medical applications as well as for laser marking plastics.
- Erbium-doped fiber lasers produce a wavelength of 1550 nm and are mainly used in telecommunications. They provide us with high-speed internet and voice over IP but are not used for laser engraving.
The use of fiber lasers is widespread due to the various wavelengths they can generate. The first step should be to look up the laser source to see its potential applications. This could prevent you from buying a laser that cannot engrave your material. For example, if you need to mark plastics and other organic materials, you may need a CO2 laser marker.
The Laser Beam Output
When buying a laser, you must look at whether the laser beam is pulsed or continuous. Some industrial laser marking systems can even switch from one mode to the other.
Let’s look at the types of beams more closely:
- Pulsed laser beams generate high energy peaks that are ideal to engrave permanent marks or pierce small holes without melting surrounding areas.
- Continuous-wave laser beams generate consistent energy levels that are perfect for laser welding, laser drilling and laser cutting machines.
Lens Configuration and Laser Parameters
Laser experts optimize the lens configuration and laser parameters for different materials and manufacturing processes. The lens configuration may include the focal length, scanning speed, spot size, marking distance, and so on. Laser parameters include the beam diameter, beam quality, pulse length, the number of passes and much more.
Laserax offers different optimized configurations for its ytterbium-doped fiber lasers depending on the metal that needs to be engraved. If you’re interested in knowing how laser parameters affect the laser process, you should read this post on laser ablation.
To know how much laser power you need, you first need to know your desired cycle time for the laser marking operation. The more powerful the laser, the faster the processing. If you are bound by short cycle times, higher-power laser engraving machines represent a good investment. Otherwise, you can usually opt for a low-power laser marking workstation.
Apart from the laser power, many factors affect the engraving time. These include:
- The font used for text and serial numbers
- The size of the engraving area
- The material that needs to be engraved (for example, aluminum is easier to engrave than steel)
- The choice to use a pale background to improve contrast for barcodes, data matrix codes and QR codes
- The marking process (for example, the deep engraving of VIN numbers requires more time)
Time estimates for laser engraving can give you a rough idea of the laser power you need. But since many factors affect the engraving time, you usually need to talk to a laser expert to determine the exact laser power needed for your application.
Based on your time requirements, Laserax can offer pulsed fiber laser markers of up to 500W to meet challenging cycle times. A 100W laser is usually enough to meet the time requirements of most industrial applications.
Before choosing a laser marking system, you usually need to gather some information about your manufacturing process. These tips can help you determine which type of system you need, but also how the system needs to be configured.
- List the materials that need to be engraved. Although a wide variety of metals can be marked with fiber lasers (such as aluminum, steel and stainless steel), each alloy has unique properties that affect how the laser beam interacts with the surface.
- Determine the information that needs to be marked if you have traceability needs. This information may include the weight, part number, mold number, date and time, and so on.
- Determine the types of markings. These may include text, alphanumerical characters, logos and codes like data matrix codes.
- Determine how much time is available for marking. Even a rough estimate can be useful in finding the right laser power for your needs.
- Start thinking about laser options. Laser engraving solutions can include a laser safety enclosure, an HMI to easily adjust the laser for different operations, a dust extraction system, an air knife to prevent dust accumulation on the lens, and much more.
- Identify the IP rating that you need. This is dictated by the environment where the fiber laser marking machine is integrated. Casting plants, for example, require a higher protection level than assembly lines. Some lasers have better protection against dust and liquid projections.
- Identify the electrical certifications required in your country. Like any electrical equipment, if the laser fails to meet these requirements, you could be forbidden from installing it. For example, the “UL” certification is in place in the USA; the “CE” in Europe; and the “CSA” in Canada.
Once you have a list of lasers that you are interested in, this information will help you quickly identify which lasers meet your requirements.
Fiber lasers are not the only option for metal engraving. Other types of lasers (such as Nd:YAG lasers) can produce similar wavelengths and hence be used for the same applications. Why choose a fiber laser then?
Different lasers can be configured differently and thus offer unique advantages. Fiber lasers offer the following advantages:
- Optical fibers offer a better beam quality (in other words, the laser beam is better focused) due to their light guiding properties. As a result, fiber lasers are more efficient when engraving metals.
- They have a low power consumption and small heat management requirement.
- They are compact.
- They have a low cost of ownership as well as low maintenance requirements, which makes them ideal for automated production lines. Manufacturers don’t need to have them recalibrated to maintain their efficiency over time.
- The laser source has a high mean time between failure (100,000 hours). This means that fiber lasers can operate full time for more than 10 years with the same high-quality results.
Understanding laser technology can help you make a more informed decision when buying a laser. To explain how each component works, let’s go over the journey of a laser beam, starting in the laser diodes, going through optical fiber, then finally hitting the part to be engraved.
The Pump Module
The laser beam journey begins when the laser diodes emit light. Passing through the fiber optics, light travels to the gain medium, pumping it with photons which, in turn, excite the photons already in the gain medium. This generates an energy buildup.
The Resonator Module
When the photons enter the resonator module, they bounce back and forth between two Bragg gratings. A Bragg grating is a piece of fiber optics with lower-density stripes in it that control which wavelengths are reflected and which are not. It acts as a selective mirror.
One of the Bragg gratings is semi-reflective, meaning that only the photons of specific wavelengths go through. These photons form the laser beam. For our ytterbium-doped fiber lasers, only the photons with a wavelength of 1064 nm go through.
The Beam Delivery
Before the laser beam generates a permanent mark onto the part surface, it goes through a lens and, sometimes, a beam expander—both of which are located inside the laser head.
The lens focuses the laser beam onto a single location, allowing it to generate enough energy for engraving. The beam expander, on the other hand, expands the size of the laser beam (usually referred to as the spot size).
A larger beam tolerates part positioning variations better, preventing adjustments between two jobs. Because most fiber lasers have a low tolerance for part positioning variations, you should pay attention to this when choosing a fiber laser.
Fiber lasers direct the beam to a specific location on the part using mirrors. These mirrors are controlled using “galvanometer motors” (or galvos), a special type of motor that can move the laser beam very precisely and at a high speed. The beam ends its engraving journey when it leaves the laser head to hit the surface.
The Final Step: Choosing a Laser
When the time comes to choose, keep in mind the type of laser source you need as well as whether the beam needs to be pulsed or continuous. Get an idea of how much marking time is available and make sure you’ve gathered other basic information (materials, traceability needs, types of markings, laser options, required certifications, and so on) to understand your application requirements.
Once you have this, run sample tests with different companies. This will allow you to make an informed decision and choose the best fiber laser for your application.
If you’re interested in learning more about our products, you can go through our range of laser machines (for turnkey solutions) as well as our OEM laser markers (for custom solutions with system integrators).