Laser marking aluminium – The application.
It is common practice laser marking aluminium weather it be machine finished or anodised. Processing on curved surface does present a few challenges but again can be completed as long as the basic rules are followed.
Depending on the lens configuration, we would normally want to keep the marking information within a 15 -20 degree segment based on the circumference. The focal point of the laser, is then set half way between the highest and lowest points of the mark field. This has provided the best chance of minimising and potential distortion to the image, as well as measurement changes to any of the information.
The combined precision of the laser beam placement along with dedicated tooling, means the part and mark are precisely aligned every time a new batch is set up.
Material is removed during the laser marking process, in order to create a contrast. It is advisable to ensure the laser marking process, scans the beam at 90° to the machining marks, in order to achieve the highest levels of contrast. The information is processed as one pass even though the surface is curved. When laser marks curved surfaces, there are constraints that effect the amount of marking that can take place.
Process parameters for laser marking aluminium
To achieve consistent white marks on aluminium the correct laser power, repetition rate, marking speed and image infill ratio must all be made. With most aluminium’s a slight deviation, either way, from the standard settings should be enough to pull back any variation you see to the mark. In some cases, it may also be worthwhile considering a second pass with much lower power settings, to lightly skim the image removing any burning by the initial process pass. With the introduction of fibre laser technology, it is now possible to create a dark image, when laser marking aluminium.
Laser marking aluminium – laser selection
In this example, we have used a flash lamp Nd:YAG laser. This is very old technology when considering what is available today. It provides the best flexibility for the material processing, which results in a commercially acceptable price point. Fibre technology could be used, providing very similar results or dark marking if so required.
In the case of CO2 I would suggest the industry would be split. If you had enough energy then you would be able to mark. Would the end result be as good as YAG technology, and would the price breaks be similar, would be a discussion that would follow for some time.
Thermark is available for those applications that need to use the CO2 wavelength, but need an enhanced mark. See our notes on applications using Thermak as part of the process.
If you would like further information on this laser marking application, or any other application, please request a call back, or talk to one of our laser marking specialists on 01737 826902.