Roll (Tesa) material marking presents a specific technical challenge in the laser industry: how to maintain consistent quality and production speed when the substrate is in continuous motion? Industries such as Automotive require solutions that combine micrometric precision with high throughput, often on delicate materials such as polymer films or multilayer laminates.
The problem is not only technical but also economic. Traditional lines require stops for loading/unloading, reducing overall efficiency by 25-30%. Continuous marking systems eliminate this downtime, but introduce complex variables: management of material tension, control of dynamic focal distance, and synchronization between substrate movement and laser scanning.
How Laser Marking on Tesa Works
The basic principle combines a controlled material drag system with a galvanometric head that compensates for the movement of the substrate during marking. Unlike static systems, here the laser must “follow” the moving material while maintaining optimum focus and writing speed.
Typical configuration includes an unwinding (unwinding) unit with tension control, a marking station with pneumatic film fixation, and a synchronized winding or cutting system. The transport speed typically varies between 50-150 mm/s, while the laser operates with repetition rates optimized for the specific material.
The critical aspect is synchronization: rotary encoders continuously measure the position of the material, transmitting the data to the galvo controller, which adjusts the scanning speed in real time. This system, called marking-on-the-fly, makes it possible to maintain marking quality identical to that on stationary material.
Focus management is another key variable. Thin films tend to fluctuate during transport, causing variations in focal distance. Advanced systems integrate laser distance sensors that automatically compensate for these fluctuations, keeping the power density constant on the surface of the material.
Operating Parameters and System Configurations
Laser power must be calibrated considering the transport speed of the material. For standard polymer films, powers between 10-30W are sufficient at transport speeds up to 100 mm/s. The critical parameter is the laser power (energy per unit area), which must remain constant regardless of the process speed.
The laser repetition frequency (typically 10-50 kHz) is synchronized with the transport speed to ensure optimal pulse overlap. Frequencies that are too low create discontinuous markings, while excessive frequencies can cause localized overheating of the film.
Control of material tension requires precision on the order of a Newton. Insufficient tension causes ripples that compromise focus, while excessive tension can damage delicate films. Professional systems use pneumatic dancers (dancer rolls) that maintain constant tension by compensating for speed variations.
The marking field width depends on the galvanometer optics used. Lenses with 160mm focal length offer working fields up to 110x110mm, sufficient for most applications. For larger formats, multi-station configurations with sequential marking are used.
Common Challenges and Technical Solutions
The quality of the winding of roll material significantly affects the quality of marking. Rolls with uneven winding tension create variations in flatness that result in focus defects. The solution is pre-conditioning of the material through tension relaxation stations.
Vapor buildup during Tesa marking can cause condensation on the optics, degrading beam quality. Localized vacuum systems and transverse airflow keep the optical path clean. Air flow rate should be calibrated so as not to affect film flatness.
Management of initial and final waste is often a hidden cost. Intelligent systems minimize this waste through predictive algorithms that optimize the marking sequence according to part geometry and roll width.
Comparison with Alternative Technologies
Inkjet printing offers higher speeds but has limitations on durability and resolution. Inks can degrade with temperature and humidity, while laser marking provides stability over time. Laser resolution (up to 1000 DPI) significantly exceeds that of standard industrial printers.
Thermal printing systems require consumables (ribbons) and have limitations on compatible materials. Laser marking eliminates recurring operating costs and allows processing of a wider range of substrates, from polyimides to thin metals.
Industrial screen printing maintains advantages on large volumes with simple geometries, but cannot compete on flexibility. Product changes that take hours in screen printing are completed in minutes with laser systems, simply by loading a new marking file.
Contact marking (punching, embossing) provides extreme durability but is limited to simple geometric shapes and requires dedicated tools for each application. Laser offers total flexibility while maintaining consistent quality on complex geometries.
Considerations for Implementation
The choice between different configurations depends on the expected production volume and the variety of materials to be processed. For throughputs under 10,000 pieces/day, semi-automatic systems with manual roll loading offer the best cost-performance trade-off. Higher volumes justify full automation with automatic roll changing.
