Process Date: March 1999

¼" thick acrylic cut at 50ipm with 100W

When cutting material under 1/8" thick, the gas pressure will have to be systematically changed to the correct level. The edge should be consistent through the depth of the cut. With thicker material, finding the correct gas pressure is a little easier - initiate the cut with no gas pressure, and then increase the pressure until the topside flaming disappears.

It must be noted that a perfect flame polished edge is not possible. The edge will have very slight vertical striations due to the periodic ejection of the vapor. Although decreasing the cut speed can eliminate these striations, micro cracking then occurs on the cut face.

For material over 1/3" thick, defocusing into the material will help achieve the best edge squareness.

As a note: because acrylic acts as a waveguide to CO2 radiation, a 2.5" lens can be used on 1" thick acrylic with reasonable results. This gives any cutting system a great range on thickness for a single set-up if a perfect cut is not necessary. Otherwise, for thicker material a 5" lens is generally recommended.

  Acrylic is an excellent material to cut with a CO2 laser. The cutting occurs as a result of material vaporization, and, with 100% laser absorption, even a 25 watt laser can cut 1" thick acrylic!

Simply cutting acrylic is straightforward enough: just select the laser power for speed required. When the thickness increases, however, and a polished square edge is required, the set-up becomes more critical.

The gas assist is key to achieving a polished edge. Air should be delivered to the material at a pressure that just enables the vaporized acrylic to be ejected through the cut, while not cooling the edge so much that frosting occurs.

As a rough guide, a pressure of approximately 1-4 psi should be used, although this is totally related to the exit nozzle diameter and the stand-off distance from the nozzle to the material. Generally a nozzle diameter of around 1/8", positioned about the same distance above the acrylic, is recommended. This offers the user good tolerance on the gas pressure setting.