CO₂ laser welders offer the typical laser-based advantages (consistent weld quality and repeatability, precise power control/beam placement, and non-contact processing) and because plastics readily absorb the 10.6-micron CO₂ wavelength, low-power CO₂ lasers can provide faster weld speeds and shorter cycle times.

This unique application points out yet another laser processing advantage: flexibility. The job requirement specified a two-part process of welding and then cutting tubular polyethylene film (6.25 mil wall thickness) to create sealed pouches.

To demonstrate the feasibility, we set up our XY cutting head with a 2.5-inch positive meniscus lens (0.004" spot with 0.07" depth of focus) and introduced nitrogen assist at 5 PSI. We created the weld seam, by defocusing the beam to provide a 0.08" (2 mm) spot size and then traversed the polyethylene film at a speed of 250 inches per minute (IPM) using 25 watts of power. Note that just as in metallic laser-welding applications, the weld interface (material gap) must ideally be zero to achieve a hermetic weld seam.

To cut the newly bonded seam, leaving a 0.04" (1 mm) wide weld on each piece, the beam was brought back into focus (0.004") and traversed across the weld seam at a speed of 400 IPM, again using only 25 watts of power.