Why choose laser marking on plastic?

Laser marking on plastic is preferable to other technologies to insert codes, logos and designs. The great specialisation of modern laser technology today allows us to mark on all types of plastics. Laser marking does not present problems such as ink adherence, contrast on dark substrates or finishing complexity.

Laser marking on plastic

Laser marking on different plastics

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.

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Laser marking processes on plastics

Carbonization

Carbonization makes it possible to create strong contrasts on shiny surfaces. During this process, the laser heats the surface of the material (to a minimum of 100° C), causing the emission of oxygen, hydrogen, or both. The result is a dark area with a high concentration of carbon.

During carbonization, the laser works with a lower than average energy. This results in a longer marking time than other processes. Carbonization can be applied to polymers or biopolymers such as organic materials such as wood, leather and hide. Mainly used for darkening, its contrast is not maximal on components that are already dark .

Colour change

Laser marking involving a color change process is basically an electrical process, which rearranges the macromolecules (by changing the direction). In this case, the material “dilates” by partially expanding. It is not removed or eliminated. The “pigment” elements in the base material always contain metal ions. Laser radiation changes the crystalline structure of the ions and the level of hydration in the crystals. Consequently, the composition of the element itself undergoes a chemical transformation, causing a color change due to the greater intensity of the pigment.

Unlike the previous processes , the laser frequency is at maximum. Each pulse has a reduced energy. This is to avoid excessive expansion of the material or the removal of part of the surface.

All plastic polymers can undergo this color change process . In most of the cases, the color change is towards a darker color; a light effect is rarely obtained.

Removal

Removal is used on multilayer plastic components (laminates). As the name suggests, this process consists of the removal of the surface layers of the base material. The color difference between the different layers creates color contrasts. This color contrast is used to create the backlit components of the cars. All Night & Day components of cars are made by removing the plastic’s surface layer.

Expansion

Expansion is a laser marking process that melts the surface of the plastic. The material, brought to the boiling point, melts. The subsequent cooling is very fast. The gasified and vaporized bubbles are found in the surface layer of the base material and create a whitish bulge. This causes a tangible, therefore embossed, marking effect. The effect of these bubbles is most visible if the base material is dark. In this case, the laser works at reduced power but with very long pulses. This process can be applied to all polymers, where the composition varies the final color: light or dark.

Laser marker for plastic: advantages

Resistance

Unlike other technologies, laser marking is indelible and resistant to wear, heat and acids. For code marking, this is essential to guarantee the traceability of the component over time. For the logo markings or graphics, this increases the recognition and quality of the brand.

Savings

Ecology

The absence of toxic chemicals that are difficult to dispose of also helps the environment, preventing the release of harmful liquids and gases into the air or water.

Precision

Laser marking allows you to create even the thinnest and most detailed geometric shapes with extreme precision.

Speed

Versatility

Integration with factory systems

The laser marker is able to interface with factory systems by automatically generating progressive codes and serial numbers and performing continuous processing.

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.

Discover the precision that makes the difference

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