Print documentation and traceability requirements are continually on the rise. Applying numbers, text, logos, and codes is part of everyday lift in the plastics-processing industry. Laser devices with varying wavelengths and active laser media satisfy modern production requirements with their high processing quality and efficiency. In contract to traditional engraving, inscribing, edging, or printing methods, laser marking's flexibility makes it a superior choice.

Marking lasers emit light within the infrared wavelength range of 1064 nm. TRUMPF (www.trumpf.com), for example, also has devices with green (532 nm) and ultraviolet (355 nm) light that can be used specifically to process plastics and semiconductor materials. The UV wavelength is opening up new dimensions in plastics marking. This shortwave light reacts directly with plastic compounds without heating the material and damaging it. Particularly in the case of critical materials, these lasers have a higher contrast-rich marking quality and operate at a greater processing speed.

Lasers can mark plastics in four different ways. The right marking format depends on the specific marking requirements and the plastic used.

For most thermoplastic materials, a change in color is achieved through carbonization?dark marking on a light background?or by foaming the material. When the matrix material is melted, gas bubbles form that are sealed in during cooling. The result is a raised mark that appears light on the darker plastic.

Engraving is a common choice for marking duroplasts and elastomers. During this process, the laser melts the material on the surface, vaporizing it. Another option is to remove surface layers. Contract is created when the surface layer is peeled away from the base material or base paint color, such as the day/night design for cars.

In the color change method, specific molecules, for example color pigments, are destroyed or structurally altered by the laser beam. A change in color or a fading of the material is visible in the areas processed. The surface of the material remains almost completely undamaged. To target the plastics precisely, the material and the laser wavelength must be optimally coordinated.

In the case of TRUMPF, the marking process is validated in an ideal manner: in close cooperation with the company's application lab. Aspects such as wavelength, marking quality (contrast, homogeneity, resolution, and clarity), marking time, and, most importantly, customer preferences play a crucial role in finding the appropriate marking laser and the optimal parameters. These variables determine the number and quality of produced parts and the cycle time.

For more information on marking plastics using TRUMPF lasers, visit www.trumpf.com.

Wed Sep 19 11:03:00 CDT 2007