laser cutting expanded foam

[Pete Bejmuk]

one company is offering laser-cut and laser-engrave expanded foam (soft foam) for transporting delicate materials (models, in this case).

http://us.battlefoam.com/categories/Privateer-Press-Bags-and-Foam-Trays/

would be good for custom guns.

Any idea how they did this? this foam is up to 5.5" thick, which is too big for the focal distance for any ULS lens. I did some experimenting with foam long ago with less than impressive results. are they using a different kind of laser than the ones we use?

[Anthony Scira]

My guess is a CNC hotwire cutter.

[paul mott]

Curious one this. Conventional hot wire usually has cuts between pockets which are subsequently glued but there is no sign of this in any of their photos. They describe the process as a "patent pending cutting system" perhaps they have developed a single ended, plunge and then cut hot wire CNC device. Although it is very easy to laser cut certain types of foam perhaps up to 5" thick I doubt it would have such straight sides as the products shown in their photo's.

Paul.

[Michael Hunter]

I regularly cut 1.5" foam with the standard 2" lens and have done 2" occasionally. Although the parts which fall out have a slight but obvious taper, once the foam is installed in the carry box the cut edges appear to the eye to be perfectly square.
I recon that with a 4" lens and enough power, you could get through 3 or 4" of foam with good results.

I have not tried engraving the foam - will do so on my next batch. Since I am paid by time (not per piece) for the foam, the extra time for engraving would put my income up, so well worth doing if it works OK!

Foam is stinky stuff to cut. I have to plan to do it on bad weather days when the neighbours are indoors with the windows shut.

[Dan Hintz]

If it is truly done with a laser, a long FL lens would be necessary, and a bit of extra power would be nice, too. Personally, I think it's using a hammer to put in a screw... I would go for modified hotwire CNC.

[Chuck Stone]

if you read the patent application, you'd think he invented the laser, the computer,
wrote CorelDraw and Adobe Illustrator. Might have invented Trademarks, too.
http://maxcdn.livingdice.com/wp-content/uploads/2010/08/battlefoam_patent_application.pdf

[Dan Hintz]

I particularly love this quote:

What has not been accomplished in the prior art is a method of successfully cutting high-density foam using a laser material processing system.
Really... it's never been done before? I suppose he isn't lying, per se, as the statement is true... it has never been accomplished in the prior art he has listed. I guess no one bothered to patent lasering a material that's done all of the time... maybe they figured it would be like patenting lasering a brick. Oh, wait, that's been done... maybe I should have said blue jeans. Dang, that's been done, too... maybe I should... nevermind.

[Greg Bednar]

Patents. - There are patents for using toilet paper to wipe your butt, a comb-over for hair, lase marking denim, etc.. Angeles Duran, a 49-year-old Spanish woman, has claimed ownership of the sun and wants to charge for monthly use of the sun. - Where does it end? ( insert expletive here )

[Richard Rumancik]

It's not clear to me that they are actually cutting a chunk of 5.5" thick foam in one pass - if they are, I don't know how they can do it. To cut that thickness with a laser you would need a VERY long FL lens (I'd say >>4") and then lots of power, but I don't see the advantage of cutting one thick slab right through anyway. Often foam cases have multiple levels plus a solid bottom. This lends itself to making 2 -6 slabs and bonding them together, but the method works well. Can someone link me to a hot-wire CNC that could do this kind of work? I have an ongoing job making tool cases for a medical instrument, with AC adapter, cord, battery pack, etc. and it seems to work well with a laser.

Dan, why do you not think a laser is not the right tool for this kind of work?

If I understand correctly with the hotwire you would have to run a contiguous cut which would mean you have a lot of vertical seams to bond. Unless you has a self-piercing/threading method. I would rather cut 1" or 1.5" slabs and bond the stack - the bonding is easy and not visible.

With the laser you don't damage the "slug" so in some cases you could cut it down and re-insert to make a different level. You can also make slits and partial-depth cuts and lots of unique features. I can't quite imagine doing my kit with a hot wire.

[paul mott]

Richard,

From what I understand reading the patent, they are cutting the material using multi-pass and re-adjusting the focal distance between passes using Z Axis control.

Paul.

[Doug Griffith]

It wouldn't be rocket science to build a hot-wire CNC with an auto feeding wire similar to a wire EDM machine. I think I'll patent it.

Richard, check out:
http://www.foamlinx.com

[Bill Cunningham]

40 years ago, I built a manual operated waterjet cutting system (no small 'electronic' computers back then) for cutting a particularly nasty, dusty, yellow hard glass expanded foam. After cutting it was being fiber glassed with a chopper and used to insulate beer vats. The waterjet was built to keep the foam board glass dust to a minimum, because it would scratch the heck out of your eyes if any got in past the safety glasses .. I should have patented foam waterjet cutting back then.. I currently use the laser to shape cut holes in 3/4" styrofoam for packing some glassware. The cut is slightly tapered to the bottom, because of the focus, and this taper works great to 'snugfit' the product.

[Richard Rumancik]

Doug - yes, this is what I visualized when Dan and others said CNC hot-wire. Generally used to cut aircraft wings and curved shapes; can also be used to cut shapes and profiles. But I can't see how this kind of machine would lend itself to making foam inserts for cases. I'll think I'd take the laser.

[Doug Griffith]

Doug - yes, this is what I visualized when Dan and others said CNC hot-wire. Generally used to cut aircraft wings and curved shapes; can also be used to cut shapes and profiles. But I can't see how this kind of machine would lend itself to making foam inserts for cases. I'll think I'd take the laser.

How bout this:
198402

[Michael Hunter]

I get to cut foam because the custom packaging company we used to use got far too expensive.

They did it Bill's way with a huge waterjet cutter - they can do 12" or more in one pass with totally perfect edges.

Because the foam comes out wet, they have to put it on racks to dry - and if someone opens the door on a windy day, the foam blows about all over the place.

[Dan Hintz]

Doug pictorialized my idea...

If I was making it from scratch, I would likely have a solid bar with one edge and the tip covered with the wire. The tip would allow for piercing to depth, followed by cutting in the desired pattern.

[Richard Rumancik]

Perhaps someone could design a hot wire cnc that could pierce but it seems like that type of equipment is not currently available. I doubt that this is the best way for Pete to go as it looks like an expensive development project.

Pete, I would suggest that you use a 4" lens and see what it can do with 1" foam. (Later, you could consider buying a custom lens - say 5"+, if you have 50w.) The kerf width will be wide with 4"FL+ but for the most part can be compensated for. I would suggest focusing into the material maybe 1/3 -1/4 of the way but you need to optimize.

Also note that the kerf will try to close up on itself after the cut. So you need to get through on the first pass. Soft foams do not lend themselves to 2-passes.

You have to keep the height limitations of your laser table under consideration. For some lasers you could replace the table so you can get the material to sit lower if need be. I can cut 1" foam with a 4"FL lens but have never tested the limits with thicker foams. No need to for my project, as I need to laminate anyway to generate multiple layers for different parts, plus usually there is a "lid" component. Even if 2 layers happen to be identical, cutting thinner slabs will be better and faster than trying to cut a 3 or 4" slab in one shot so you don't lose that much overall, except you need to bond. With thinner material the edges will be cleaner and the fumes can escape better.

I have been using clear silicone as an adhesive to bond the layers of polyethylene foam. It works, but I am on the lookout for something better.

[Michael Hunter]

Richard

The "professionals" use adhesive film (similar to 3M 468, but with a few random fibres in it) to laminate layers of foam.
The stuff must be relatively inexpensive, since we are often supplied with laminated sheets when ordering "standard" thicknesses.

From my experience, cutting 1" foam should work fine with a 2" lens unless you are exceptionally fussy about having absolutely vertical edges to the cuts.

The 1.5" PU foam I cut (with a 2" lens) goes into carry cases for instruments costing £20K to £30K each : the customer never noticed the change from the original waterjet ones to mine, so the quality must be acceptable.

With 2" foam and a 2" lens, the slope on the edges becomes a little obvious, but would probably be OK for most purposes.

[Richard Rumancik]

Thanks for the info Michael. I use 468 tape for some things; PSA would probably work, but based on what I pay for 3M tape it won't be cheap for me - the 2" (48 mm) tape in single rolls costs me about $2/ft sq - it is $60 for a 55m roll. Even at half the price it adds up fast, plus I think there would be too much waste for my parts.

I also would be concerned about a little bit of PSA tape sticking out. I use a fixture to align my stack but you can be a little bit off with compliant parts. With a liquid adhesive, I can keep the adhesive a little ways from the openings and outside edges, so there is no adhesive visible. So I think I am biased toward a liquid adhesive but find the silicone doesn't bond as well as I'd like. It's fairly quick to apply as I dispense from a large plastic syringe.

[Tony Lenkic]

Richard,

You can buy 3M 468MP in rolls of 12" by 60 yard long for 180.00 That would be $1.00 square foot. Where do you get yours from?

[Chuck Stone]

If I were to tackle a project like that, I'd probably consider making some sort of jig
to compress the foam down to a thickness my laser would work with. Might need
templates that can be registered and held down in place, perhaps pausing the
cycle to move/arrange the parts that hold down the foam?

Maybe sandwich the foam between firm plates that already have the 'kerf' cut
out.. Pins go through the foam and secure top and bottom?

Dunno. The brain is free-wheeling. That's not always a good thing.

[Belinda Barfield]

I cut a lot of custom tool box foam. I cut 1" foam with a 60 w laser with no problem. For tools and equipment that require deeper foam the customer provides foam with adhesive backing. They just stick the layers together.

[Chris DeGerolamo]

I cut some foam last week for HTC for use in one of those 007 looking silver cases....anyone have a good supplier for foam? I'm looking for something that I can cut to replace the foam in my Glock case as well as an AR-15.

[Chuck Stone]

toolfoam.com is one place I've used. Get samples and test them on the laser first.
Some of them are well suited to the 4th of July..