Foam with Laser

[John Gill2]

We have a 30w Laser, and we are trying to cut foam for transport trays. (Cut out hole, put object in hole, it's protected) We are having some issues on the 1"+ sizes. We are cutting medium density open cell foam. It's cutting the foam, but sometimes is needing a second pass. or because the beam's focus is to short it's not concentrated enough to get all the way through.

what ever the cause, the edges are getting melted and the cuts are not looking great. Also we are producing a lot of smoke and staining the foam.

any thoughts or tips on how to improve this would be great!

[paul mott]

John,

Have you tried setting the focal point so it is about 1/3 the way into the work before you start cutting ??

Paul.

[John Noell]

You might want to consider using a longer focal length lens (e.g., 4") as that will give greater depth of field. If you are 1" away from the focal point of a 2" lens the beam is pretty wide and the result can be messy.

[Richard Rumancik]

John, I cut 1" open cell gray urethane with a 30 watt using one pass and it cuts well and looks fine. I use a 4" lens and focus maybe .20" into the material but you can experiment with focus anf find the optimum. The gray color does tend to hide smoke residue. With a light color it might not be acceptable. I think you need to cut in one pass because foam is not stiff enough to keep the kerf open for the second pass. If it closes, then you are attempting to recut and you will not get consistent results around the perimeter of the piece.

Since you say the edges are "melted" them perhaps you are using a polyethylene foam? Urethane won't melt; it lasers by decomposition.