Vacuum infusion question

[Tailgunner]

I have been looking for some information regarding the vacuum infusion process for making boats. I found this nice little video on youtube that gives some more information:

http://www.youtube.com/watch?v=iZPWZxVq9h8

However i do get lost towards the end of the video.

They say they put peelply on the laminate and a bit later they place the silicone rubber bag.

But I think there also needs to be breathercloth on top of the peelply before you place the rubber bag. Do you need to use any other layers? To bad they don't mention them. I believe that breather cloth is visible in the video underneath the vacuum bag but i'm not sure.

To create the vacuum they use a plenum with two gaskets. One that seals over the rubber bag and one that seals on a clean part of the mold. Don't see how you can get a vacuum seal if the vacuumbag lays on top of the breather cloth. And how does the vacuum get to the laminate if there are two seals.

Also, does resin flow through the peelply?

Maybe someone could clarify some of this.

[KnottyBuoyz]

Originally Posted by Tailgunner

But I think there also needs to be breathercloth on top of the peelply before you place the rubber bag. Do you need to use any other layers? To bad they don't mention them. I believe that breather cloth is visible in the video underneath the vacuum bag but i'm not sure.

No breather required. Breather layers are used in vacuum bagging processes to absorb excess resin. In an infusion any excess resin will flow to the vacuum tube and into a trap. In a large infusion you might have a layer of infusion media (screen mesh) to aid in resin flow across the layup.

Originally Posted by Tailgunner

To create the vacuum they use a plenum with two gaskets. One that seals over the rubber bag and one that seals on a clean part of the mold. Don't see how you can get a vacuum seal if the vacuumbag lays on top of the breather cloth. And how does the vacuum get to the laminate if there are two seals.

Their tool probably has a channel made into it that goes around the entire perimeter. The plenum probably has a separate vacuum pulled between the two gaskets to hold it firm to the tooling surface (flange). The plenum probably doesn't sit on top of any peel ply, I'd trim it off to ensure a good seal. Maybe the omitted that step. Leaving the peel ply short of the plenum would create a resin brake when it gets to that point and prevent a lot of resin from flowing out of the layup.

Originally Posted by Tailgunner

Also, does resin flow through the peelply?

Yes.

[AndrewK]

I have not watched the video.

Yes resin flows through peel ply.

There are 3 basic ways to infuse a laminate, through the reinforcement itself, over the top resin transfer media, grooved core.

With the core and reinforcement alone approach there is nothing else to go on top of the peel ply, you only need perforated release film under the resin feed lines. Even peel ply is not essential but good to use.

Over the top transfer media is what I assume the video was showing, on top of the peel ply perforated release film is placed then the resin flow media, resin feed lines and then the bag. If you do not use the perforated release film it will be very difficult to strip the media.

Search BD there have been a number of infusion discussions.

[Herman]

I checked the video. Without sound, however, so no clue on what they are explaining.

I guess the trick indeed is in the silicone bag, in this situation. It has channels for the vacuum (perimeter) and for resin flow.

The only remarks I can make are that his workers wished a longer cutting table, and that he should be more easy on the spray glue. (I sell the same, really, a quick mist is enough, even less then he uses).

This silicone bag is an investment. If you want to experiment, you are better off using a nylon bag. Andrew already said, but depending on your laminate you might need a flow medium.