Process Date: April 2004

The four tubing samples shown with this application illustrate typical marks obtained when using CO₂ lasers to mark plastic components. This application was not developed to determine maximum mark speed or optimum mark quality, but rather to demonstrate the different marking mechanisms seen when working with various plastic types.



TYGON^® is a clear laboratory/chemical grade of PVC tubing which produces a lightly engraved, high contrast mark. Other types of PVC tubing and PVC coated wire also exhibit nicely contrasting marks. The contrast, or color change, is induced by heating of the substrate. Mark velocity was 30 inches per second (IPS) using 14 watts of power.

The urethane (green) tubing provides an engraved, non-contrasting mark. At a power setting of 14 watts, urethane tubing marks slightly slower than PVC at a velocity of 25 IPS.



Nylon 11 (red) tubing exhibits a slight contrast caused by a combination of engraving and a light melt-back on each side of the depression. Marking speed was 20 IPS at a power level of 26 watts.



The last example, polyethylene (blue) tubing, provides a slight contrast caused by yet another type of marking mechanism – surface melting. Instead of engraving by material removal, the polyethylene tubing melts at the surface, changing density and volume. This property change on the tubing surface creates a raised mark. Mark speed was 10 IPS using 33 watts of power.

Other dark-colored plastics such as phenolics (including Bakelite) and polycarbonates typically exhibit engraved marks; however, at very low powers (less than 10 watts) these plastics will also mark through the surface melting mechanism, creating a high contrast mark. Careful control of speed and power causes the surface to boil (instead of vaporize) and then quickly cool, which produces a raised mark. The dramatic change in density and volume causes this raised mark to appear much lighter than the surrounding darker surface.

All marks for this application were made using an FH Series marking head fitted with a 125 mm lens. Focused spot size was 180 microns (0.007”) with a 3 mm (0.118”) depth of focus.