CO₂ lasers perform a variety of cutting and marking processes in the food industry due in part to the sanitary nature of the laser’s non-contact operation. A growing trend in recent years is to customize food products by marking a brand logo or image on the product.

For this feasibility study, our marking setup consisted of a firestar f201 laser and an FH Smart marking head. A 200 mm focusing lens (290 micron spot size with a 5 mm depth of focus) was installed on the Smart FH head to obtain the required line width in the mark.

Cutting Polyimide-Coated Glass Capillary Tubes

In a recent newsletter, we demonstrated CO₂ laser cutting of thin glass substrates measuring between 30 to 600 microns (0.0012” – 0.0236”) in thickness. This week’s new application carries the glass-cutting process several steps further as it involves cutting polyimide-coated glass capillary tubes. These capillary tubes, used in the manufacture of precision microfluidic devices, range in diameter from 123 to 363 microns (0.0048” – 0.0143”).

The 2.5” optic provides a 100-micron (0.004”) spot size with a 1.8 mm (0.07”) depth of focus. The assist gas, used for protecting focusing optics and ejecting vaporized debris out of the cut path, was five-PSI nitrogen.

Three capillary tube samples with varying internal diameters (ID) and outside diameters (OD) were cut. The first sample, a polyimide-coated tube with a 100-micron ID and 363 micron OD, was cut using 60 watts (W) of power at a speed of 35 inches per minute (IPM). The second sample (shown in the photograph) had an ID of 30 microns and an OD of 363 microns and was cut using 60 W at a speed of 100 IPM. The third sample, 30 micron ID / 123 micron OD, was cut with 60 W at a velocity of 150 IPM. Using these cut parameters, we were able to control melt back of the polyimide coating, keeping it to within 50–90 microns (0.0020” – 0.0035”) of the cut edge.