Anodising has become a dominant form of finishing for aluminium. This is largely due to its cost effectiveness, availability and suitability, across a whole host of applications and industrial sectors. Laser marking anodised aluminium panels, has also become an accepted process across these industrial sectors.
What is Anodised Aluminium
Anodising is an electrolytic passivation process. It changes the microscopic texture of the aluminium by modifying the crystal structure near the surface. The passivation thickness will be between 10 and 25 microns, generally between 10 and 15 microns where colouring is used. This makes laser marking anodised aluminium very cost effective, as the layer can be removed easily and quickly. The laser is used to vaporise the top surface, removing the area affected by the anodising, and this exposes the aluminium material below. When a darker dye colouring is used, the contrast levels are very good.
The quality of the finish on the aluminium relies heavily on the material quality. With poor quality materials (high levels of alloys), the grain structures have a tendency to tear leaving rough surfaces and edges. The higher the quality of the base material, the higher the quality of the mark result, and the closer to white the mark will appear.
If you need any more information, check out this post on The Anodising Process Explained.
Laser Marking Anodised Aluminium Panels
In this example, the equipment front panels have corporate branding details added as well as some contact information. Because the images are quite large, the panels are processed using high power to start. Then we finish off using a second pass, with lower power effectively skimming the image.
Aluminium corrosion: The general consensus is, as the laser removes the anodised layer, an oxide layer forms on the surface providing protection.
CO2 lasers can also be used to process anodised aluminium. In this case, it is the dye that is directly affected rather than the material. The energy from the laser creates a heating action that removes the dye from the surface. The use of CO2 is generally not as well received as Nd:YAG Laser or Fibre laser due to the lower quality created by the mark process. This is directly related to the fact that the heating effect is difficult to control, due to “heat creep”. Although, per unit cost will be slightly higher with CO2 due to the process time being slower.
The benefit of CO2 laser marking anodised aluminium, is that the anodised surface is not damaged in any way by the CO2 laser source. This means there is no compromise in the integrity of the surface and no potential corrosion point. In applications such as aerospace and marine, where corrosion is a major risk, CO2 laser parking is usually preferred.
Our range of Lightblade Laser Engraving machines are perfect for CO2 laser marking of anodised panels and products. Their large Z-axis travel allows for products up to 250mm in height to be marked.
Our Lightscribe Fibre Laser Engraving Machines are a great choice desk top solution for fibre laser marking anodised aluminium panels. For the fibre laser marking of larger products, check out our Custom Design & Build solutions.
Of course, if your application does not justify the purchase of a laser machine, then you can always get your products marked by our experienced sub-contract services team. Let us take the strain of your product marking needs, until you are ready to bring the work in-house with a proven manufacturing system from Thinklaser.
If you would like further information on this laser marking case study application, or any other laser based, product marking, product identification or product branding application, please request a call back, or talk to one of our laser marking specialists on 01737 826902