In previous editions, we have demonstrated the use of specialized coatings to enhance CO2 laser marking of certain materials. These products provide the ability to obtain low power (25–40 watt), high-contrast, permanent marks on materials that are normally reflective to the CO₂ wavelength including copper, brass, chrome, and silver. In addition to brushed or sprayed coatings, several manufacturers have incorporated their coatings into label tape technology. For each part, a labeler advances the tape, holds it in contact with the part surface during laser marking, and then peels up the tape on a rewind spool leaving only a permanently bonded laser mark on the part.

The accompanying photo provides an example of this type of mark. The part, a chrome plated 7/8” deep socket, exhibits a high contrast mark that indicates the size of the socket. For this application we selected a Firestar v40 laser along with an FH Series Index marking head.

Using WinMark Pro to develop the mark file, we first created a text object and gave it the Text Caption “7/8”. On the Format tab, we selected “TrueType” for Font Type and chose a TrueType font installed in the marking computer’s Fonts folder. We set Text Height to 0.2” and Text Curve Detail to 600. On the Marking tab, we set Velocity to 10 inches per second (IPS), Power to a duty cycle percentage corresponding to 40 watts, and Resolution to 600. The three-character mark was completed in 1.81 seconds and is permanently bonded to the plated socket.

Using specialized coatings laser marks can
be obtained on a wide variety of materials that
are traditional reflective to the CO₂ wavelength.