Plastic materials have vastly different chemical compositions. In fact, polycarbonate, polyamide, polyester, PE, PET, ABS, to name a few, are all plastics. Their various compositions mean different outcomes for any processes applied to them, including laser marking. The choice of laser, in terms of required wavelength, depends on the type of plastic involved.
PET, for example, requires a specific short wavelength of 9.3 μm, which you can get with CO2 laser markers. A laser with a different wavelength could overheat the plastic, causing micro-holes and burns. Laser marking on this semi-transparent plastic results in white characters that seem to float on the surface. From PET bottles to thin films, by using the correct laser source and parameters for making, laser marks on plastics always delivers results that are clear and sharp.
The different laser sources and the extensive specialization of modern laser technology currently allow us to make laser marks on all types of plastics. Laser marking is better than other technologies for placing codes, logos, and designs on plastic components. Compared to ink jet, laser marking does not have the problem of ink adhesion, dark substrate contrast, or finish complexity. This is because the laser removes or changes the surface of the plastic material, or modifies its color, creating a contrast.
Carbonization creates very dark marks on very bright surfaces. When an area receives continuous high energy, the macromolecules of the element around the base material are charred and turn black.
Color change, for example from dark to light or vice versa, using a laser ensures minimal damage to the component during marking.
With selective ablation, the laser removes a surface layer from the material.
The most popular lasers for marking plastic are the well-known UV laser, the FlyPeak green wave laser from LASIT, and the traditional green light laser with a fiber optic source. In many cases, we can also recommend using a MOPA laser (variable pulse). Because of the ability to control pulse timing, this laser performs exceptionally well, even for some difficult applications.
Laser technicians perform tests to determine which laser will deliver the desired results on specific plastics. Starting from the results of the first tests, they can identify the parameters that work best for the specific job. The initial parameters they use are normally the ones listed below:
In most cases, forcing a marking can be counterproductive and decrease the final contrast. That’s why it’s better to start with one repetition and gradually increase from there.
Below, we have identified the three most common plastic materials used in laser marking, describing their characteristics and the best parameters:
This material, unless additives are used, can be marked fairly well with an infrared FiberFly laser, a FlyAIR Green Wave green light laser, and perfectly with a FlyUV laser. The FlyUV laser induces a photochemical reaction in the material, producing high, continuous, and permanent contrast, leaving the surface smooth to the touch.
The Infrared FiberFly laser provides good contrast, and the MOPA version is recommended when increases contrast is desired.
Controlling the heat input is a key factor in achieving quality laser marks on plastic.
The pulse of the FlyPeak laser always stays below 10 ns throughout the range (at 20 kHz = 3.5 ns). This means the surface stays cooler compared to traditional nanosecond lasers, including fiber lasers. The result is increased laser mark quality.
The FlyPeak laser marker uses a DPSS (diode pumped solid state) system, which combines high peak power with a much shorter pulse than other solid-state lasers on the market, while keeping the average power unchanged. There is no better performing laser currently on the market.
The best features of this laser marker are: