question about infusion

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#1

Here is a pic of my mold, when I run my vacuum line would you run spiral wrap around the whole outside flange and wrap it in peel-ply so the air can travel or would you just set the suction line and thats it? If you need clarification I can try

#2

would be handy if people could draw on the pic with paint shop to show where to put the parts :slight_smile:

#3

gotcha working on it now :slight_smile:

#4

Should I do it this way. I tried it before but half of my resin was sitting in the spiral wrap around the mold by the time it gelled. Would I be fine without the spiral around the mold. I was just shown to do it this way is why I ask

#5

what does the spiral wrap do? i didnt see that on evans demo.

#6

is that a tail part from an mr2?
does that spoiler have undercuts?

L.

#7

it is a rear cargo cover for my integra. Are pumps effected by elevation? My brand new robinair pumps pumps full at 25hg, my second used one pumps at the exact same level.

#8

well again the resin took over an hour and a half just to gel so it sucked most of the resin out of the piece. I am going to try another resin, what can I use to thin out normal poly? for testing purposes

#9

If your system doesn’t have any leaks (no vacuum drop in an hour), why don’t you pinch off, with a tube clamp or something, the vacuum side of the process once the part is infused? It will still be under full vacuum as it cures, but it won’t have the driving force pulling resin out of the part. I use epoxy exclusively so I don’t have any experience with PER or VER.

-Bob

#10

if these were not a cosmetic part but one that serves a function I would use epoxy. Do you know if pumps are effected by elevation?

#11

evans tutorial doesnt say when to shut the vaccum off? i would think you must have to shut it off as soon as the part is fully infused or it will just suck it all out??? he mentions making sure there are no vacuum leaks at all,i really dont know but i would have imagined that the vaccum must be cut early on???

#12

It’s not so much the vacuum pump’s function but the atmospheric pressure is less the higher the elevation. The pump still draws out all the air, but the column of air pressing down on the surface isn’t the same as if you were at sea level. Less molecules of air pressing down the higher you go, so the amount of vacuum is directly related to the height above sea level.

Here’s a simple chart that show the aprroximate maximum vacuum you can expect given the elelvation…

http://www.pumpworld.com/atmos.htm

-Bob

#13

Thanks for that info on the pumps. It is right, we are 4,900ft and it is pumping at 25hg

#14

you can thin PER with acetone.

#15

i have been introducing air from small small leaks I think that is what is causing the void and the small bubbles

#16

i completley got rid of the bridging now I have what it looks like long trails of bubbles. well one bubble about 1/62 of an inch wide but about 4 inches long where it looks like the air was tring to get to to suction port but got trapped there and was moving till the resin finnally geled enough that it got stuck.

#17

im sure infusion calls for full vacuum? if you can only get 25" because of your location then maybe it will never work??

#18

The only recommendation I can give you is to make absolutely certain that your system is leak free and de-gas the resin to remove any possible air bubbles that were created while mixing in the catalyst/hardener. This is what I do when infusing my epoxy parts.

I agree with gtfour, 25" Hg is really not sufficient for decent infusion unless the parts are pretty small or the flow field is short and can infuse pretty quickly.

#19

I am infusing a hood in about 2 minutes so I am not having any troubles with it infusing, I have 5 drift boat manufactures in a 100 mile radius that infuse all their boats at 25hg so that is not the problem, how do you de-gas the resin? I called robinair and they said that even though i am only pushing 25hg that even though the elevation that it is equivalent to 29hg at sea level. So 25hg at 4,900ft elevation is full vacuum from what they told me. but that is only with rotary vain pumps not the oil-less ones. My problem is I am pretty sure that I am introducting air into it. It infuses perfectly but about 10 minutes later I start seeing little air bubbles traveling through that laminate.

#20

3 possible reasons I can come up with - and could it be a combination of all 3.

  1. You have leaks in the bag, seal, or mold.

  2. Micro bubbles you introduced while mixing the resins are expanding once the resin is infused. This is the reason I mentioned degassing the mixture previously.

  3. The resin has some volatile chemical component that comes out of solution and forms a gas under vacuum. gas=bubbles

To degas the mixed resin takes time and I’m not sure you have that luxury with PER or VER. Basically you put the mixture in a vacuum chamber and apply a full vacuum to it. This causes the bubbles to expand and rise out of the mixture and pop. If you ever witness it under glass you’ll be amazed at the amount of bubbles introduced in even the most gentle of mixing. It literally forms a foam head just like beer as the bubbles are pulled out of solution.