Emission-Free Marking of Color Films
It is increasingly common to place identification labels on parts during assembly. A multi-layer film with a laser-activated inner layer offers many benefits in this regard.
Laser marking of films is becoming increasingly important for the logistics of production processes. With conventional identification systems, the laser beam removes the top layer of the film at defined locations. The colored layer underneath then becomes visible. This method is relatively slow and energy-intensive. Moreover, the resultant marking is very susceptible to mechanical abrasion, since a protective cover layer is not present. In addition, when “burning away” the top layer, large amounts of dusty and gaseous emissions are formed that require exhaust hoods and frequent filter changes.
The current issue of the magazine Kunststoffe reports that, in contrast to the above, multi-layer color laser films permit emission-free marking. In this case, the process takes place inside the multi-layer structure. Energy is absorbed in the laser-active layer and induces a physical chemical reaction, therby exposing the color layer underneath. In this way, extremely fine shapes and characters can be produced with precise, sharp edges at high speed and with little energy input. A transparent laminated layer protects the laser-active layer beneath it. A broad spectrum of colors provides new design opportunities.
Assurance of product originality is growing increasingly important in the face of higher product liability. More and more manufacturers are employing solutions to prevent product piracy and unambiguously distinguish original parts from counterfeits. Custom safety features such as holograms can also be integrated into color laser films.
The color laser film features self-destruct capabilities that exclude tampering with the identification label. The multi-layer structure of the material is destroyed during any attempt to remove the label from the substrate. This capability is activated, however, only after about 15 minutes, so that incorrectly applied labels can be removed and repositioned without being destroyed during this time interval.
Special film for painted parts
When labels are integrated early into manufacturing of parts, the production process can be monitored continuously with the stored information. This is aided by a special protective film: after marking by means of laser, the labels are applied in the first step of production and subsequently proceed through the entire assembly process, including the painting operation. The information is accessible up to the painting step. After painting, it becomes available once again upon removal of the protective film. The edges of the laser-marked label thus exposed are embedded in the paint.