Laser engraving on metal: how to set the parameters

The laser engraving technique is a process that involves the removal of the material from the blank, by burning or vaporizing the surface. 

To ensure efficient machining, you need to know the composition of the material and how to set the machine to the correct parameters.

Let's see in detail everything you need to know for laser engraving on metal materials.

Components of materials

Here are the main features to consider when engraving metals. 

• Hardness

Metallic materials have different hardnesses, requiring specific processing methods. For example, to engrave on harder materials such as stainless steel and titanium, it is necessary to set a higher laser power. In contrast, softer materials, such as aluminium and copper, can be machined with less power.

• Thermal conductivity

Thermal conductivity is a critical factor in metalworking. In fact, highly conductive materials, such as aluminium and copper, can quickly disperse the heat of the laser beam. In these cases, it may be necessary to adjust the power of the beam to obtain clean and precise incisions.

• Chemical reaction

Some metallic materials can react chemically to the laser, generating fumes or oxidation products, so it may be necessary to use auxiliary gases or extraction devices, to ensure the quality of the engraving.

• Fusion and annealing

It is important to carefully check the laser parameters to avoid melting and get clean engravings. In fact, some metallic materials such as copper have a low melting threshold. 

Also remember that stainless steel, if exposed to the laser, could suffer the effect of annealing by changing its properties.

How to set the laser beam parameters

Now that you know the aspects to consider about metal alloys, it is important to know which machine parameters to monitor.

• Power

The power of the laser (in Hertz) can vary depending on the hardness of the material and the type of processing you want to achieve: engraving or marking.

In fact, if the engraving technique involves the removal of material, that of the marking works by removing only a surface layer.

• Frequency speed

The frequency speed indicates the speed with which the laser must work the workpiece.

The higher the speed, the lower the exposure of the surface to the laser. 

For example, for photoengravings, the speed chosen is usually quite low. On the contrary, the engravings on license plates take place at a higher speed. Carefully evaluate the type of material to check the right speed to set.

• Pulse duration

In the case of pulsed light lasers, the pulse duration refers to the length of time that elapses between one pulse and another. The shorter the pulse, the greater the power of each. 

In addition, among the laser settings it is possible to change not only the duration, but also the length and width of the pulse.

Conclusions

First you need to know the composition of metals and other alloys, as these have to be processed based on hardness, thermal conductivity, chemical reaction, melting and annealing. Once the characteristics of the materials have been verified, the laser parameters (power, frequency speed and pulse duration) must be adjusted on the basis of the material and the type of processing required.

Only by carefully monitoring all these aspects, it is possible to obtain precise and high-quality processing.