Plastics are derivatives of a wide variety of chemical compounds that affect the quality of processing processes, including UV laser marking plastic. Plastics include polycarbonate, polyamide, polyester, PE, PET, ABS and much more. The characteristics of the material influence the choice of a laser that emits a wavelength of the required wavelength.
A typical example is PET material, for which a short wave (9.3 µm) is used for marking. A wave of this length can be obtained using CO2 laser markers. A laser with a different wavelength can cause the plastic to overheat, resulting in pinholes and melted edges. Laser markings on this almost transparent plastic are applied in the form of white characters that seem to float on the surface. In order for the marking of PET products – from bottles to thin-film materials – to turn out to be of high quality and well visible, you need to choose the right parameters for the laser.
Various laser sources and a wide range of modern laser technologies allow label almost all types of plastic, however, if the composition contains coloring pigments and other additives, then the reaction to the laser may be different. Laser marking is preferred over other technologies for applying codes, logos and designs to plastic parts.. Compared to inkjet printing, laser marking eliminates issues such as ink adhesion, contrast on dark substrates, or the result of difficult finishes. The better result is because the laser removes or changes the surface of the plastic material or its color, creating a contrast.
The most popular lasers for plastic applications are the famous UV laser, green laser LASIT FlyPeak and traditional green laser with fiber optic source. In most cases it is recommended to use UV laser marking plastic with adjustable pulse duration. With pulse width control, this laser delivers maximum performance in the most demanding applications. Laser technicians carry out all the necessary tests to determine which laser is best suited to achieve the desired result on specific plastics. Typically, the following options are initially used. Based on the results of the first tests, the best methods suitable for marking a particular material are determined.
- High speed (900-1200mm/sec)
- Low frequency (10-20kHz)
- Low average power (30-60%)
In most cases, excessive marking intensity can be counterproductive and reduce the final contrast, so it is best to start with 1 repetition and gradually increase the number of repetitions.
