Laser engraving technology is one of the laser processing technologies. Laser engraving is a marking method that uses a high-energy density laser to locally irradiate the workpiece to vaporize or change the color of the surface material and perform permanent marking. Laser engraving can produce different words, symbols and patterns.
Laser engraving machines are used when speed and high precision are required. For example, electronic components, medical components, promo gadgets, jewelry, automotive parts, plastic buttons, hydraulics, tags and so on. The laser spot is so thin that allows us to focus precisely on microscopic surfaces.
Laser engraving works by using a focused beam of light (the spot) to mark the surface of a material. When the beam interacts with the material’s surface, it alters the material’s properties and appearance. This concentrated beam targets only a specified area, allowing the laser engraving machine to create precise, high quality, high-contrast marks that are easy to read or scan on virtually any surface. This feature makes laser engraving ideal for applications where accuracy and permanency are critical to success.
The most common laser is the fiber laser, who is effective on all the metals and the majority of plastics, considering also its MOPA and Picosecond versions. This laser operates at 1070NM, delivering significantly higher power to mark harder materials, such as metal.
Another example can be the UV laser marker, which has a wavelength of around 355NM and offers a lower power for marking heat-sensitive materials such as plastic and glass. Because UV laser markers and other machines in the “cold laser” category emit less energy, they are great solutions for many organic or soft products, as they are less likely to burn the material. Compared to other non-permanent marking processes such as printing or labeling, laser engraving uses no consumables and requires less maintenance.
Laser engraving is a process that vaporizes materials into fumes to engrave permanent, deep marks. The laser beam acts as a chisel, incising marks by removing layers from the surface of the material. The laser hits localized areas with massive levels of energy to generate the high heat required for vaporization.
Would you like to find out about the LASIT solutions for your field?
Request a free consultation.
One of our experts is standing by to answer your questions
and find the best solution for your requirements.
Very often laser marking and laser engraving are used as synonyms, but they actually refer to two different processes. They both imprint an indelible mark on a material by means of a laser beam, but while the engraving vaporizes it, the marking dissolves it
The melted surface expands, creating grooves up to 80 microns deep, altering the roughness of the material and creating a black and white contrast, depending on the laser parameters used. Later we will look more specifically into what the black and white color of the marking depends on.
Let us specifically analyze the 3 steps by which marking takes effect.
1
All laser marking or engraving methods have one thing in common: that the laser beam is pulsed and releases energy at specific intervals. In one second, a 100W laser releases 100,000 pulses. Each pulse contains one millijoule of energy and can reach 10,000W peak power.
To control the amount of energy emitted by the laser, you need to adjust its parameters, which every technician knows. The most important parameters are speed and spacing, which determine the distance between pulses. The closer they are, the higher the concentration of energy.
With laser engraving, the pulses are much closer than with marking. This is because marking requires less energy than engraving, so it is faster. Speed is precisely one of the decision-making parameters when it comes to choosing between one process and another.
2
The surface of the material reflects most of the laser pulse energy, while the rest is absorbed and converted into heat. For marking to be carried out, the material needs as much energy as it requires for melting, and therefore less energy than it would need to evaporate as in engraving.
As soon as the energy is transformed into heat, the temperature of the material increases until it reaches its melting point. At that point, the surface heats up and becomes malleable, allowing its shape to change.
For a solid-state laser emitting a wavelength of 1064 nm, aluminum absorbs ≈5% and steel more than ≈30%. From this last figure, one would think that it is therefore easier to mark steel, but this is not the case. We have to consider other physical properties, including the melting point of the materials.
3
As the material melts and cools in milliseconds, localized changes occur on the surface. The surface roughness changes, creating the permanent marks that are the content of the marking: a code, a logo, a graphic.
Color changes appear as a result of different patterns on the surface. For high quality laser markings, white and black offer the best contrasts.
White marking
Black marking
Now that we understand the difference between the two processes, let’s now define what are the main parameters that lead us to choose one over the other:
1
Laser engraving penetrates the surface more deeply and is recommended for all those components that are at risk of wear due to the environmental conditions in which they will be set, or that are subjected to post-marking process surface treatments such as sandblasting, shot peening, e-coating or heat treatments
2
Marking is a process that takes less time than engraving, precisely because it penetrates the surface of the material less deeply. If the component is not subjected to particular stress, such as with home appliances, electronic, promotional and jewelery components, marking also guarantees speed mixed with the permanence of the result, which is superior to all related technologies.
3
Surface before laser engraving
Surface after laser engraving
As already explained, while marking dissolves the material by modifying its roughness, engraving sublimates the material by creating grooves. To do this, the laser must be powerful enough to vaporize the material in a few milliseconds and the material to be marked must have an adequate sublimation temperature, so deep engraving is not always possible.
When laser engraving occurs, it is important that the laser marker is equipped with a suitable exhaust system. LASIT has designed its exhaust fan, specifically designed to maximize the level of protection of both the environment and the laser itself.
Did you like this article?
Share it on
LASIT Sistemi e Tecnologie Elettrottiche S.p.A.
Via Solferino 4
80058 – Torre Annunziata (NA)
P.Iva 02747991210
C.F 01803670643
Copyright © 2024