Cutting XPS foam

[Mcyoda]

I am planning to cut many 1/2" thick board from 3" foam. How smooth can you get from using CNC hotwire method. Is smooth enough to use for sign? I have saw many video cutting EPS but haven't see one that is cutting XPS.

[CNCJohn]

Mcyoda,

XPS cuts well on our hot wire machines. It cuts a bit slower because of it's density, but it's real clean on the edges when doing lettering, or faces when slabbing. It shouldn't be an issue which foam you use.

Typically you see EPS foam with hot wires because XPS usually doesn't come in larger blocks and thus is used mostly as is in thinner panels, not for architectural trim and the like. XPS also is a bit different with regard to the heated off-gases. It's not as toxic as some foams, but it's a tad worse than EPS from what I've heard. It uses different blowing (or expanding) agents when produced. EPS is very clean to cut (biologically speaking), and burns cleaner than wood.

Hope this helps,

John

[Mcyoda]

Thanks John,

Will it be a problem if I cut 5 slice from 3" XPS at the same pass? I was concern it might be sticking togther because of the weight.

Thanks

[CNCJohn]

Will it be a problem if I cut 5 slice from 3" XPS at the same pass? I was concern it might be sticking togther because of the weight.

There shouldn't be any problem with weight or sticking.

The only concerns I see are the issues of burnout - from a 3" board your 1/2" slices may become 1/2" minus 1/16" or something close to this. If the end thickness is critical, you might just need to cut 1 less per 3" board and space the wires apart a little farther till you're within your specs.

[Mcyoda]

There shouldn't be any problem with weight or sticking.

The only concerns I see are the issues of burnout - from a 3" board your 1/2" slices may become 1/2" minus 1/16" or something close to this. If the end thickness is critical, you might just need to cut 1 less per 3" board and space the wires apart a little farther till you're within your specs.

The final thickness is not that critical.

Thanks