Engraving barcodes, serial numbers, and logos on metals with lasers is a very popular marking application on both CO2 and fibre laser systems.

Fibre lasers are ideal for industrial marking applications due to their long operating life, lack of maintenance requirements, and relatively low cost. Lasers of this type produce a permanent, high-contrast mark that is not affected by part integrity.

In order to engrave on bare metal with a CO2 laser, the metal must be treated with a spray (or paste) prior to engraving. CO2 lasers use heat to bond marking agents to bare metal, creating permanent marks. In addition to marking wood, acrylic, natural stone, and other materials, CO2 lasers are also fast and affordable.

Epilog manufactures laser systems that can be operated from almost any Windows-based software and are remarkably easy to use.

Differences between lasers

Due to the different effects of different laser types on different materials, some considerations have to be made.

Metals require more time to be marked with a CO2 laser, for example, due to the requirement of coating or pre-treatment with a metal marking agent. The marking agent also needs to be able to bond with the metal at a low speed and high power. If the mark can be wiped off after lasering, then it’s time to run the piece at a slower speed and higher power.

By using a CO2 laser, marking metal does not remove material, so the tolerance and strength of the metal are not negatively impacted. It is also important to note that treated metals do not require pre-treatment such as anodized aluminium and painted brass.

Fibre laser engraving is the best method for engraving metals bare. Laser fibres are ideal for marking many types of metals and engineered plastics including aluminium, brass, copper, nickel-plated metals, stainless steel, and many more. 

There are, however, some materials that are difficult to mark with the laser wavelength emitted by the device; the beam, for instance, can pass through transparent materials, leaving marks on the engraving table instead. While fibre laser systems can be used to mark organic materials like wood, clear glass and leather, that’s not necessarily their ideal application.

Marks and their types

An array of fibre Laser marking on metal options is available depending on the type of material to be marked. Engraving involves vaporizing material from an object’s surface using a laser. As a result of the shape of the beam, the mark is often shaped like a cone. By repeating the cycle, the system creates deep engraving that will not wear under harsh environmental conditions.

Often, ablation involves removing a top layer to reveal the material underneath. Powdered and anodized metals can all be ablated.

The surface of an object can also be marked by heating it. The annealing process leaves a high-contrast mark on metals by creating a permanent oxide layer by exposing them to high temperatures. Foaming occurs when there is a melting of a material’s surface, making gas bubbles that become trapped as the material cools, producing a raised effect. The polishing process involves reversing the colour of a metal surface by quickly heating it. The end result is a mirror-like finish. Annealing is used for steel alloys, iron, titanium, and other metals high in carbon and metal oxide. Most often, foam is used to mark plastic, but it can also be used to mark stainless steel. There are no metals that can’t be polished, but darker metals with matte finishes tend to produce the best results.

Materials to Consider

In addition, stainless steel may be marked using annealing, etching and polishing techniques by changing laser data such as speed, power, frequency, and focus. Often, fibre lasers are able to achieve much greater brightness when used on anodized aluminium than CO2 lasers. The fibre laser produces shades of grey when it engraves bare aluminium, not black. In addition, deep etching of aluminium can be done using oxidizers or colour fills.

It is important to keep in mind that titanium can also be marked by lasers – the laser tends to create a wide range of colours. It is possible, however, to produce marks of various colours by adjusting frequency.

Best of Both Worlds

Due to their versatility and capabilities, dual-source systems are a good option for companies with budget constraints or limited space. One drawback of this method is that when one is in use, the other is useless.

Graded white, grey and black marks on anodized aluminum

Different marking effects are created by removing colour or material from aluminium. Anodized layers can be removed by laser in part or in their entirety. 

Aluminium is anodized to produce a ceramic layer (5 to 30 m thick) that protects the surface and makes it scratch-resistant. Decorative marking effects can be achieved by colouring the porous layer. Different laser wavelengths produce different marking results (and therefore thinner or thicker layers of material are removed), as well as layers beneath. 

Machine-building frequently uses anodized aluminium, for example. g. This section contains parts for housings, covers, adjustment screws, etc.