The requirement for marking the Delrin LED cases shown below, is to laser mark a four-digit code, readable under a microscope, to aid product traceability. This was easily accomplished using a Synrad C02 laser as CO2 lasers produce a nicely engraved mark on most plastics. Since the cathode of each LED is marked with a swatch of green ink, a high contrast mark was obtained, readable even by the naked eye.
What makes this application special is that a very small character height of only 0.5 mm was required in order to fit the four-digit text string onto the 2.7 mm wide LED body. To accomplish this, a 80 mm focusing lens is fitted to a Synrad FH Series marking head and Synrad 10 W sealed CO2 laser. Using Synrad’s WinMark Pro laser marking software, a four-digit text object was created with one of WinMark Pro’s built-in stroke fonts. Cycle time for this very small mark is a fast 60 milliseconds.