PVA and infusion

General Composites Discussions Composites Talk
#1

Well guys, i changed up my method from my first infusion. On the first one i sprayed spray glue into the mold to hold the carbon fiber down to the shape of the mold… bad move on my behalf.

This time after waxing the mold 10 times, waited 20 minutes inbetween coats. I then sprayed 3mils of PVA over that. The first layer of carbon fiber into the mold… i sprayed the cloth just ever so slightly even coverage, holding the can about 16 inches away from the cloth with spray glue, 3M #45 again. Also i infused about 25 minutes after applying the spray glue. It worked like a charm… awesome glossy smooth finish on the parts this time. Last time the parts had a lot of pourosity on the surface after they were pulled from the mold. Smooth as glass this time. Just some minor blemishes from the mold surface. The mold gel coat surface has some minor pin holes in it that the wax and pva did not fill in completely.

Overall, even though the infusion was a disaster, the parts actually came out looking decent. Just all dry around the edges of the part, and dry areas on the backside of the parts also.

Hey, I learned some cool stuff though.

  1. 3M #45 works great, just don’t let it sit for too long after spraying.

  2. PVA and the spray glue are very compatible with each other.

  3. PVA improved the surface finish of this part.

  4. You can never have a perfect enough mold surface.

  5. I love infusion :smiley:

#2

infusion sucks, prepregs the shit

#3

Don’t burst his bubble ya bastard :smiley:

#4

ha, wasnt tryin to burst his bubble, ha, but I guess I did, oops,

#5

right on, q for you, for the first layer of carbon that you placed in the mold, was this the carbon you said you sprayed with glue? just to hold it in place I guess right?

#6

yeah, i sprayed one side of the first layer of cloth in the mold. Just to help it hold the shape.

I’ll probably never do prepreg. too much money for a freezer, the material itself, and then an oven, and then tooling that can withstand oven temperatures. Bottom line, it’s too expensive, and it’s overkill for the parts i make.

#7

well, as a hobbyist it is not too practical, but as a business it really makes the best sense for many reasons

#8

Most of those making ornamental composite motorcycle parts here in the UK on a commercial basis are using pre-preg materials.

Just cant see how you could ever make parts as cost effectively using vacuum infusion, as in the case of fastrr the mould preparation time alone would make this a total diaster commercially.

#9

Yeah, the capital investment in a freezer and 2000$ roll of pre-preg ain’t for the faint of heart! Plus needing an oven with some sort of control.

Damn I can’t wait to get a house…and BIG shed.

#10

where is there a difference in the ool preparation. I would assume you had to prep the tool in either case, (vac bag pre preg or vac infused?
I haven’t done pre-preg in years an only had aluminum tooling then.
We need to compare apples to apples.
I have to wax and spray green seal now, but i do admit i also spray clear polyester gelcoat into the tool. then i apply the material and lay it in. apply peel ply and then flow media
As i remember we applied the material and then peel ply, and then breather cloth and then on either process you add the bag.

#11

I almost forgot. We are getting parts from the tool that need little to no polishing and just have to trim them

#12

you got to understand that cost of part is so small compared to labor cost, this why prepreg pays for it self, you can laminate in half the time, and have unskilled workers producing high end parts repeatedly. also with use of a cutting machine, or some one who is efficient you can all most be 100% efficient with your material, very little throw away. after the intial investment of a oven and hightemp tools, it pays for it self