EPDM Foam to Laser Cut

Anyone tried laser cutting through EPDM foam? It is 1/8" thick, adhesive backed. I am just checking if it’s safe before I experiment with settings to find optimal. Has to be this material for the product project I’m working on, but if dangerous I’ll manually cut it.

Specifically, it’s McMaster Carr P/N 93725K202 (https://www.mcmaster.com/93725K202/).

Any opinions and knowledge would be greatly appreciated!!

The MSDS should tell you. If you are unfamiliar with the look for combustibility and what gases are given of when burned. And if you see chlorine anywhere in the chemistry of it don’t even put it in your GF.


Flamability is a 1 - slight risk


Stability and Reactivity

Chemical Stability: Stable at normal temperature and storage condition.

Conditions to avoid: Overheating

Incompatibility with other materials: No specific information is available, however strong oxidizers or reducing agents which generally not compatible with compounds.

Hazardous Decomposition Products: Fumes produced when heated to decomposition temperatures may contain carbon monoxide, carbon dioxide, hydrogen cyanide, oxides of nitrogen, and small amounts of aromatic and aliphatic hydrocarbons. Combustion products from rubber, like those of other natural and synthetic materials, must be considered toxic.

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I’d consider it safe as it is just a derivative of polyethylene but there is always the second question and that is how does it cut? I’ve seen things that are as safe as acrylic that just doesn’t cut worth a hoot. If you can’t find someone who has tried it there is only one way to find out if it does well with a co2 laser.


Likewise, but just to clarify: Safe for the laser, not for your lungs. Ventilate well and give it a whirl while you’re on fire watch.

Then report back :slight_smile:


Appreciate you looking this up!

Agreed, I have the filtration setup and I’ll run the fans full speed. Will report back later with the deets.

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I’d be careful with the fumes. Hydrogen cyanide is nasty.


Alright… I experimented and optimized a decent amount. Someone could pick it up where I left off in the future to optimize for sure, but a decent start. Can someone please add this info to the shared google doc settings spreadsheet? Or I can if you send me link to where it is (forgot)…

BE SURE TO VENT TO A FILTER… LOTS OF SMOKE AND SOME IS UNSAFE TO BREATHE IN. I used an enhanced external fan routing smoke through tubing into the GF filter.

1/8"th EPDM Foam + Adhesive backing:
3 passes, Speed 500, Power 55
Clean cut through foam (with clean edges).
Did not cut through the adhesive backing layer except slightly in corners where laser slowed down.
Slight flash/fire burn on top surface but not bad.

1/16"th EPDM Foam + Adhesive backing:
2 passes, Speed 400, Power 50
Clean cut through foam on straightaways, but burned on slowdown corners.
Did not cut through adhesive backing at all.
Slight flash/fire burn on top surface but not bad.

So three passes is a lot, how come you ended up doing multis instead of a heavier single?

It took 100% power + Speed 200 to cut all the way through at the 1/8"th. At those settings it was burning the top surface (actual fire that would extinguish on it’s own shortly after the laser moved away), and badly charring the foam. Not to mention tons of smoke.

Probably a way to get down to 2 passes with still minimal top flash/burn that someone could figure out. Maybe 2 passes, Speed 400, Power 65.

Wow that must be tough stuff. I have only fooled with EVA and polyurethane foams and they are super wimpy.

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Yeah EPDM is meant mostly for weatherstripping, so very tough even though it’s low density.

It’s hard to tell visually but I think the material was part vaporizing and part melt pooling downward. So I’m guessing the first pass went ~50% through the thickness, then each pass after had to deal with more density and so only did maybe ~30% of the remaining thickness on the second pass.

With EVA you see shrinkage away from the cut. If you hit it too hot your effective kerf gets really wide. Did you see any of that in your foam?

I didn’t notice it getting especially wide, maybe the normal laser width or a tiny bit wider. And no flaring at the top relative to the deepest points. Sidewalls of the cut still show exposed foam cells so it looks like it wasn’t melt bonded… (my melt pool theory is not happening)

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