Engraved contasting marks can be created on Ferrite insulators using 25W of power.

Ferrite is a class of ceramic electro-magnetic material known for its high magnetic permeability and high electrical resistivity. Ferrite toroids are used as cores for transformers and inductors in power conversion devices while ferrite beads are commonly used as RF chokes or EMI (electro-magnetic interference) suppressors. Although ferrite varies in color from silver-grey to black, enough contrast is created by the CO₂ laser interaction to provide visible text and readable 2D Data Matrix codes.

To mark the ferrite insulator core shown in the photograph, we fitted our FH Series marking head with a 125 mm lens to obtain a 180-micron (0.007”) spot with a 3 mm (0.118”) depth of focus. This allowed us to mark 15 mil (0.015”) cells with an overall 2D code size of 4.6 mm (0.18”) square using 25 watts of power at a mark velocity of 18 inches per second.

Because filled cells sometimes overlap unfilled cells, leading to poor print growth values during verification, careful attention to resolution settings is important. In this case we set a marking Resolution of 250 to prevent overscanning. These settings resulted in the completion of a raster-scanned code in a cycle time of 0.48 seconds. Using an RVSI CM4000 vision system, we obtained read rates averaging nine milliseconds while achieving an overall AIM (Association for Automatic Identification and Mobility) grade of “A”. AIM’s Bar Code Print Quality Guideline allows verification systems to grade directly marked codes for acceptability with grades ranging from A to F for contrast, axial uniformity, print growth, and error correction.