Graphite Composites

[Odlaw]

I have read several posts about this topic, but each one says a different thing. Can we or can we not use graphite composites. If not can we use fiberglass. We practically have Scaled Composites, as in SpaceShipOne, sitting in our backyard. They have said they will help us with whatever we need. As of right now we are going to use fiberglass, but if we can we'd like to use graphite composites. Any help would be greatly appreciated.

[Max Lobovsky]

There are absolutely no material restrictions (I'm wrong, see next post). Last year, I saw robots with carbon fiber, fiber glass, titanium, etc, etc.

[Cory]

Originally Posted by Max Lobovsky

There are absolutely no material restrictions. Last year, I saw robots with carbon fiber, fiber glass, titanium, etc, etc.

technically, incorrect.

You can't use any hazardous materials. graphite composites are fine though, just make sure to account for them properly.

[Max Lobovsky]

Yes, I forgot the obvious "but it has to be safe" qualifier.

[Odlaw]

Originally Posted by Max Lobovsky

Yes, I forgot the obvious "but it has to be safe" qualifier.

So as long as the graphite doesn't splinter into a million lung cancer causing pieces, we're ok?

[Tristan Lall]

Originally Posted by Odlaw

So as long as the graphite doesn't splinter into a million lung cancer causing pieces, we're ok?

Well, 96-100% pure graphite is considered carcinogenic according to this MSDS; carbon fibre, however, seems to only be an irritant, per this. Check the appropriate MSDS, and have a copy for the inspectors. They can and will demand to see one, if there's any question in their mind about the nature of the material.

[Gdeaver]

WE have used fiberglass pultrusions in the past. They're off the self and inexpensive. We used 6 OZ plain weave carbon and amine epoxy to make a large pulley for the arm. Again, the raw materials are affordable and we provide the labor. Most carbon is custom made for the application. If you include the set up cost for a custom tube you'll find that it's a budget buster. If I were a first inspector I would pay close attention to invoices for carbon structures. As far as safety, RT curing epoxy is relatively safe, but some people are allergic to amine epoxies in the uncured state. Prepeg materials are different. Some prepeg epoxies are very toxic in the uncured state. I would not want students laying up prepegs in the shop. So yes you can use composites, But your team should look at the health, safety, and cost issues before committing to use them.