SYNRAD, INC. - http://www.synrad.com  
Thursday, July 22, 2004
Issue 92

SYNRAD's sealed CO₂ lasers are used in a variety of industrial processes including cutting, welding, drilling, and marking. This news brief showcases some of the interesting materials and products that are processed daily by Synrad's line of CO₂ lasers and marking heads.

Cutting Acryl (PMMA) Film

Close up of PMMA Film
 

This particular CO₂ laser cutting application accurately trims oversized artwork to exacting final dimensions. The image is screen printed on sheets of 312-micron (0.0125”) thick acryl film covered with a protective backing. An FH Series marking head with a 125 mm focusing lens provided beam delivery to cut the shape, although an XY table would work in cases where artwork is too large to fit into the mark field of the lens. Focused spot size was 180 microns (0.007”) with a 3 mm depth of focus.

We first imported the full-size CAD drawing into WinMark Pro using a Vector Import Scale setting of “One-to-One” (under Tools, go to General Settings…, and then click the Object Defaults tab). We then set a Power value corresponding to 50 watts, set Velocity to 8.5 inches per second (IPS), and choose a Resolution of 150. To further reduce cycle time, we increased Off Vector Velocity (non-marking galvanometer speed) to 150 IPS.

Overall cycle time to cut the outer shape as well as the inner keypad area is 1.84 seconds, which is over three times faster than the current mechanical cutting method.

Marking Glass Mirrors

close up of 2D Code on Glass Mirror

Glass marking is a proven application for CO₂ lasers and mirrored glass is no exception – the silver surface is ablated and the underlying glass substrate is control-fractured as in a normal glass mark. With this process, text and barcodes marked on the mirror’s back side are easily visible from the front.

We marked this sheet of mirror glass with an ECC200 Data Matrix code using a firestar v40 laser, FH Series marking head and WinMark Pro laser marking software. The marking head was equipped with a 125 mm focusing lens that provides a 180-micron (0.007”) spot size and a 3 mm (0.118”) depth of focus.

In WinMark Pro, on the Marking tab, we set a Power value of 33 watts, a Velocity of 15 inches per second, and a Resolution of 50. We then set Spot Marking Style to Yes, and entered a Spot Mark Duration of 10 (1 millisecond). On the Format tab, we set 2D Barcode Bitmap to No and set 2D Barcode Circle Radius to 50%. When these property values are specified, here’s what happens: The 2D Barcode Bitmap property (No) forces WinMark to mark each filled cell using circles instead of raster-filled squares. With Spot Marking Style set to Yes, the circle is marked by a series of discrete spots and as Resolution is lowered, fewer and fewer spots are marked to define the circle’s circumference. At very low Resolution values (50 is the minimum value), only a single spot is marked for each circle (barcode cell). Finally, Spot Mark Duration keeps the beam on for a specific period of time, which in the case of glass, controls heat input and fracturing.

Cycle time to mark the 15-character code was 1.09 seconds and we read the resulting mark on both glass and silvered sides using scanners from Microscan (Quadrus EZ) and RVSI (CM4000 vision system). When scanned from the rear (silvered side), we achieved overall AIM grades of “B” with individual grades of “A” for Symbol Contrast, “A” for Print Growth, “A” for Axial Uniformity, and “B” for Unused ECC. Although passable grades are achieved when scanning 2D codes from the front side of the mirror, Print Growth grades drop somewhat (depending on the angle of the mirror to the scanner) because the scanner “sees” the reflected image as well.

Perforating holes in plastic / fabric sheet

0.025" diameter holes made with 15W at 1200ipm

Placing a number of holes to be identified by vision systems is an excellent and simple means of tracking/identifying fast moving sheets. In this application, hole sizes between 0.004 and 0.05 were produced in a number of thin fabrics, using less than 25 watts of power.

The laser was externally gated to provide the desired hole size and spacing for different line speeds.

The photo to the left shows the "YN" of Synrad. The acceleration/deceleration of the moving table is evident in the variable spacing of the dots.

Browse Synrad's Applications Database

Search our online library for more applications of Synrad's sealed CO₂ laser technology. Sort by material, process, or industry.

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