All Plastics Are Not the Same
To speak of plastics is to refer to derivatives of very different chemical compositions, which influence the performance of the processes applied to them, including laser marking. Among plastics, it is indeed correct to distinguish between polycarbonate, polyamide, polyester, PE, PET, ABS, and many others. These influence the choice of laser in terms of required wavelength.
A case in point is PET, which requires a specific short wavelength (9.3 μm) obtainable with CO2 laser markers. A laser with a different wavelength would risk overheating the plastic, causing micro-holes and burning. On this almost transparent plastic, a laser marking is obtained in which the white characters appear to float on the surface. From PET bottles to thin-film materials, laser marking with the right parameters will always be clear and sharp.
Laser marking processes on plastics
Foaming
Foaming is a process that melts the surface of the plastic. During this process, gas bubbles are created in the plastic, which are included in the material during the cooling phase. Due to the gas contained, the volume of the affected material increases and the laser-treated parts appear raised.
Colour change
Colour change is the change of colour from dark to light or vice versa. The use of a laser to irradiate the plastic ensures minimal damage to the component during marking.
Selective Ablation
Selective ablation of surface treatments or paints, or the controlled removal of a protective coating on plastics, is used for a variety of purposes, including Day&Night applications, where removing the paint defines the shape of the button to be illuminated.
Lasers marking on plastic
The most common lasers for plastics applications are the famous UV laser, the FlyPeak green wave laser by LASIT and the traditional Green light laser with fiber optic source. In most cases, the use of a MOPA laser or variable pulse laser is recommended: thanks to pulse duration control, this laser ensures maximum performance on more difficult applications.
Laser technicians carry out tests to see which laser is best for achieving the desired result on specific plastics. Usually, the parameters initially used are those listed below. Based on the results of the first tests, it is possible to identify those best suited to the specific processing desired.
Test parameters
High speed (900-1200mm/sec)
Low frequency (10-20kHz)
Low average power (30-60%)
In most cases, insisting too much on marking can be counter-productive and decreases the final contrast, so it is better to start with 1 repetition and gradually increase them.
We have identified the 3 most common plastics in our experience, describing their characteristics and the best parameters for marking them.
For full reports and further insights, please download the brochure.
ABS White
If not additivated, it is marked with a traditional fiber laser. However, the ideal laser is the FlyUV, which achieves: high contrast, impalpable marking, durability.
PA66 GF 30 Black
Good contrast can be achieved with FiberFly infrared lasers. To increase contrast, the MOPA version is recommended.
POM C Black
Good contrast can be achieved with FiberFly infrared lasers. To increase contrast, the MOPA version is recommended.
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