Very often, laser marking and 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 µm 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.Get more news about Laser Marker U3100,you can vist our website!
1. The laser beam hits the surface of the material (FIGURE 1). All laser marking or engraving methods have one thing in common: the laser beam is pulsed and releases energy at specific intervals. In one second, a 100 W laser releases 100,000 pulses. Each pulse contains 1 mJ of energy and can reach 10,000 W peak power.
2. The material absorbs the energy of the laser beam. 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.
3. The localized surface expands and its roughness is altered. 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, or a graphic (FIGURE 2).
Laser engraving, on the other hand, vaporizes the material. The laser beam penetrates deeper into the surface and removes the upper layers by sublimating them, or rather through a direct transition from solid to gaseous state. This is because the laser hits localized areas with a high intensity of energy and therefore heat.
Now that we understand the difference between the two processes, let’s define what the main parameters that lead us to choose one over the other:
1. Marking resistance. 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 (FIGURE 3).