High Density PR Foam Sheets

[Delta C]

Greetings, all.

I am researching cnc routers for my business. A large part of what we do is foreign object control systems (FOD) for military and various industries. Meaning we cut high density (4 or 6 lbs) polyethylene foam sheets as tool box liners, with tool shapes cut out of the foam. More examples are on our website.

I would like to know what experiences any of you may have had cutting such foam. I would like to offer as a service the ability to contour the foam to better fit specialized tools. Is this doable? Is this doable for under $10,000?


Thanks for the help.

[steve_g]

Sean

My experience is limited to 2 and 4 lb material... Polyethylene foam does not machine well. It's really just controlled tearing out of chunks! In one project involving night vision equipment, we roughed out the shape and then pressed a heated mold into the cavity... even that was prone to a lot of failure! It die cuts really well and is the best method to use when the numbers can justify it... hot wire cutting works well for low volume when the profile is 2D. For one off prototypes of 3D inserts, I machine them and follow that with a flame to burn off most of the fuzzies... Good Luck!

SG

[CNYDWW]

I don't have any experience with this type of foam. A couple questions come to mind, however. What are your options as far as tools to cut the materials? How does it cut with a laser or even an ultrasonic knife? I would contact ShopBot directly and see about those options mounted to a machine. I've heard they're developing a laser and considering the recent development of their 5axis cnc router, adding a vertical rotary 4th axis to a standard machine for the knife could be doable.

Regards
Randy

[Delta C]

We currently use laser and water jet to cut our foam liners, but are looking at adding, perhaps, a router into the mix as we sometimes get requests for thicknesses beyond what we are currently capable of achieving. In addition, a router can cut to depth in 3D. An added value.

Some of the videos we have seen on You Tube seem to show routers cutting approximately four to six inches in depth. The cuts look relatively clean, so I am pretty sure it can be done.

There are instances where we are required to 50+ tool boxes at a time

The typical dimensions we deal with do not, usually, exceed 30" x 60".

[chiloquinruss]

"Some of the videos we have seen on You Tube seem to show routers cutting approximately four to six inches in depth. The cuts look relatively clean, so I am pretty sure it can be done."

The question was can you cut foam, the simple answer is yes! However what kind of foam makes a tremendous difference. SIGN foam is very ridgid. PACKING foam is very soft and pliable.

Router bits cut things that are ridgid.

Router bits DO NOT like soft and pliable. :)

I use a hot knife or hot wire to cut packing foam. Russ

[Delta C]

The foam that we use is not as rigid as sign foam, but not as nearly as pliable as packing foam. It is pretty dense material.

I know that it can be done. I have seen it. I am curious as to the experience anyone here may have at cutting it. Upon further research it does look like it can be done for under $10,000.

But I think I will take the advice from an earlier comment and contact Shopbot for more concrete answers.

[bleeth]

Sean:
Perhaps you should ask for volunteer botters in your area to do a demo and take some foam that you normally use with you. There are a lot of friendly botters in the Northwest.

[seana]

Sean,
I'm in Bothell (just north of Seattle) and would be happy to run some test cuts for you.
You can either send some scrap and i can play with it or come on over and we can play together so you can see the machine at the same time.

Sean

[Delta C]

Sean-

I might just take you up on that offer as I am in the Seattle area pretty frequently. Would you be available tomorrow (Friday, August 17th)?

What type of router(s) do you have?

[JDaVinci]

I am very curious if you get this figured out. I have cut a lot of this foam and always use a hot knife or have it laser CNC cut.

I wouldn't know where to begin putting this on the shopbot. I'm nearly positive it would be a disaster. I've accidentally drilled into flexible foam on occasion, and the results are not good. I can't imagine how bad it could get at a higher RPM and with less of an ability to "release the trigger". Also, it looks like you need some really tight corners. The problem with a hotwire (we also have a Hotwire CNC) is that it needs in and out cuts between each part. You cant put the bit into the material, then remove it to reposition like you can with a spinning bit.

I would say your only option for results like you've pictured, from PE foam is to cnc Laser cut it.

My hot knife works well on the foam, it's how I make a lot of my costumes:

[sailfl]

Those are great. I bet the kids love them.

[peelio]

Sean & Sean,
Did you guys ever get anywhere with this?

Thanks,
John

[Burkhardt]

A diamond cut carbide burr (http://www.mcmaster.com/#carbide-burs/=os4c14) or other coarse abrasive bit might work better than an end mill in soft foam. But I am not sure what cutting speed is possible.

Edit, just noticed it is an old thread, never mind.

[gundog]

Sean I am about 3 hours West of you near Vancouver, WA I am hosting a camp for Shopbot the 19th of this month bring a sample and we can try a cut before or after the camp if you attend.

Mike

[jerry_stanek]

Sean I am about 3 hours West of you near Vancouver, WA I am hosting a camp for Shopbot the 19th of this month bring a sample and we can try a cut before or after the camp if you attend.

Mike


Why not talk to Bill and see if he can arrange a little session on cutting this. There will be a lot of ideas there.

[chiloquinruss]

I'll bring my swivel knife and we can play with it too! Russ

http://donektools.com/d2-drag-knife/