CNC mold making material?

[BorisGeorgiev]

Greeting, everybody!

I am a member of a Formula Student team and my task is to research about suitable materials for CNC molding.
Our general idea is to use either epoxy resin or plastic vacuuming when manufacturing our bodywork parts. However, firstly, we need to have our molds done via CNC machining. I was wondering if PU foam would be an appropriate material for this application? If not, could someone shed light on this matter and suggest any possible material(s)!

Thank you in advance for the attention!

Regards!

P.R: Hope, this thread is at the right place!

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[LeeWay]

You could cnc machine foam with a large enough router and rather long tools. Then you could skin coat the mold with fiberglass and mesh for strength and be able to reuse the mold many times.

[BorisGeorgiev]

So you mean that when we are finished with the CNC and make the mold from PU Foam, we can cover it with fiberglass thus producing stronger material? I was worrying if we decide to make the bodywork parts via plastic vacuuming...Will the mold material withstand the high temperatures ( around 190 degrees, if i am not wrong )? Also, do you think that PU foam will not react in some with the fiberglass?

Thank you again!

[LeeWay]

I'm pretty sure it is done in boats and surf boards this way as a finished product. It is also used in tanks, pipes cars and lots of other uses.
You may not be able to remove the foam though and that would react to high temps.
I think the fiberglass could withstand that particular temp.

This is from the web and what temperatures can be run through fiberglass piping safely depending on the resin used.


Recommended operational temperature ranges for fiberglass pipes:

Epoxy glass fiber reinforced pipe: -29 to 149 oC (-20 to 300o F)
Vinyl Ester glass fiber reinforced pipe: -29 to 93 oC (-20 to 200 oF)
Furan glass fiber reinforced pipe: -29 to 93 oC (-20 to 200 oF)
Furan carbon fiber reinforced pipe: -29 to 93 oC (-20 to 200 oF)
Phenolic glass fiber reinforced pipe: -29 to 149 oC (-20 to 300 oF)
Polyster glass fiber reinforced pipe: -29 to 93 oC (-20 to 200 oF)



You might be better off machining both the foam for rough finish allowing for the fiberglass and then fine tune the fiberglass mold itself with the same machine and a ball end mill.