The laser marking of plastic components with laser receptive additive is normally marked with an ND:YAG laser. The component has Iriodine added to enhance the laser mark. In this instance the customer Classic Closures required a highly visible and crisp laser mark on a variety of colours.
There are a number of differing changes to the material surface during laser marking, and is very dependent on the material itself as to which one occurs.
- A thermochemical foaming, creating gas bubbles to the surface of the material, is the most common. The light scatters across the affected area producing the light marking that appears.
- Bleaching is another effect that is common. Here, the pigment used to achieve the product colour is removed creating a visual difference.
- The third mechanism is vaporisation where the material is heated, very quickly, to the point where it vaporises, and is removed leaving behind the created image.
These three laser marking effects can be enhanced by, the adding of laser sensitive additives and can generate considerable advantages. The additive acts as an abortion barrier, boosting the ability of the laser to process better. In some materials the laser marking ability would not be possible without this additive.
The process removes dye from the material to create the image. Iriodine creates a more even absorption barrier providing an even contrast across the part. Iriodine was one of the original materials developed by Merk, that could be used to add to materials where laser processing did not usually provide good marking.
The nozzle is laser marked on both sides, and therefore we use a rotary indexer to rotate the part, so that the marking is completed in a single process pass. Although the nozzle is cone shaped, the position of the laser focal point, is set to minimise any distortion as the beam travels down the length of the part during the mark process.
If you would like further information on this application, or any other application, please request a call back or, talk to one of our laser marking specialists by going to our contact page – link below.