Laser Engraving Aluminium with N-Lase Desktop, Benchtop, Workstation
Laser Engraving Anodised Aluminium
Anodised aluminium is one of the most common metals used for laser marking purposes. Aluminium itself is a very widely used metal which is valued for its combination of being both lightweight and durable. This unique combination has made it the material of choice for aircraft and automotive products. The high electrical conductivity of aluminium has also made it an excellent material for long-distance power lines, satellite dishes, and in electrical components found in most household appliances and power systems.
Laser engraving anodised aluminium for technology devices
Aluminium is a very malleable and ductile material which makes it a versatile material for many consumer goods. Modern smartphones, laptops, and tablets are made with increasingly large portions of aluminium. Being light and easy to shape, the metal is also becoming a common component in chairs, lamps, decorative panels, and other interior design elements. Aluminium is food-safe, non-toxic, and resistant to rust – after all, aluminium cans have been used to package carbonated drinks since the 1960’s.
Anodised aluminium is essentially aluminium enhanced with a corrosive-resistant layer. Similar to how stainless steel is produced, the anodised layer is made by a process called passivation. This is done by immersing the the metal in an acid electrolyte bath and passing an electrical current through the solution. The result is a thin coat of aluminium oxide that is fully integrated into the underlying aluminium substrate, making it resistant to chipping away or peeling off. The anodised layer is generally stronger and more adherent than any other anti-corrosive paint or metal plating treatment, making anodisation one of the more preferred options.
Aside from giving aluminium better UV and corrosion resistance, an anodised layer has a naturally porous surface that is especially receptive to dyes. This has allowed manufacturers of this metal to offer their product in a wide variety of colours. Without dye treatment, the anodised layer is translucent and reveals the metallic sheen of the underlying aluminium – a finish that looks good enough on its own.
The types of anodised aluminium marking
The presence of the anodise layer makes the metal an especially easy material for for engraving and marking purposes. A fiber laser or a CO2 laser can be effectively used with anodised aluminium, since they can both ablate the anodise layer. Depending on the thickness of the anodise layer and whether a dye was used to colour the layer, different laser treatments may be used to get the best results.
A coloured Type I or Type II anodise layer is the easiest material for laser engraving anodised aluminium. These layers are very thin at less than 1/1000 of an inch and can be ablated away with minimal energy and contact time. Since the anodise layer is bonded to the aluminium layer at a molecular level, an ablation process changes the surface of the original aluminium layer. The result is a scattering of light that gives a colour intermediate between white and clear. The use of a dye on the anodise layer, especially one of a dark colour, creates excellent contrast with the ablated section.
A thicker anodise layer, called a Type III layer, can also be ablated using a fiber or a CO2 laser, but will require a higher laser power output, a longer exposure time, or multiple passes. In any case, at least two passes are generally recommended for marking the aluminium by ablation. The first pass, called the “damage pass” ablates away the anodise layer. The second pass, called the “cleanup pass”, removes any excess material and brightens up the ablated section. The result is an ablated section that has a better contrast to the coloured anodise layer.