Composites
This week's assignment, was to design and make a 3D mold, and produce a fiber composite part in it.
Some time ago I worked on a design of a mechanical flower at fab lab MET, the project was discontinued, because of time and budget, so this week I decided to continue and try to improve the design, focusing on the petals, I wanted to make them more 3D and curvy.
This was the original design, as you can see the petals were really flat:
So I modeled the new petal in inventor and next and exported it to rhino for creating the mold, because for me is easier to make differences between solids in that software.
This is the design of the petal:
And this is the mold:
I milled a block of wood in the shopbot, first I used pine wood, but the result was bad because the wood was too porous, and some parts weren’t smooth enough, I milled two blocks of pine because I thought that the problem was this specific block of wood but both blocks went wrong, so I decided to use a harder wood, I used a spare block of Huayruro wood, that I had from a previous project (guitar shaped), this time the milled went good.
For the fiber i wanted to experiment with glass fiber and natural fibers (yute).
For the matrix i used polyester resin:
The mix:
Polyester Resin, "Cobalt" (Activator-1.5%), "Peroxid" (Catalyst-0.5%)
*This can change depending on the ambient's temperature
As you can see the natural fibers that I chose didn’t worked well, I think they can work on bigger objects. The glass fiber worked nice, it copies the form of the mold really well.
i have to make a total of 5 petals but first I want to look for other fibers, and maybe add some color, this is the result of this week’s assignment. I've got a piece very strong and flexible:
conclusions:
- Fiber = good for tension
- Resin = good for compression
- Temperature affects on the time of curing
- harder wood is better for molds
- Basic polyester mix = Polyester Resin, "Cobalt" (Activator-1.5%), "Peroxid" (Catalyst-0.5%)