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Old 12-11-2016, 06:59 AM   #1
smp4616

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Default Why does this work?

I've been doing well with infusion for a while now and would like opinions on why this works: on a laminate of 4oz then 2x11oz 2x2 twill, on pva, with peel ply backed by green flow media, small resin brakes of 1/2" every 3", a perfect surface finish is achieved by pulling full vacuum, allowing a flow rate of about .5"/minute, then curing at 5-2psi. previously I was attempting to cure at full vacuum, and/or allow full flow rate, or omit flow media except in a small line down the center of the part, all of these left voids between weaves at the surface, no bubbles, but voids. my theory as to why it works has a lot to do with the rate of saturation in the tow due to capillary action. I believe what's going on is the slower flow rate allows more time for the saturation of the fiber, and curing at a lower vacuum increases the rate of capillary infusion into the tow by opening the fibers up enough to overcome the viscosity of the resin, since the inlet line is closed, I also believe the flow media is creating a reservoir of excess resin to be drawn from as the fibers pull more resin via capillary action. anyone else have theories on this? I can't leave good enough alone and would like to really understand what's going on so I can apply it to different situations.
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Old 12-11-2016, 02:24 PM   #2
herman

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If you pull a (near) full vacuum, then infuse, then release teh vacuum somewhat, the voids will implode.

You create a pressure differential between resin and void, and the void loses...
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Old 12-11-2016, 02:29 PM   #3
smp4616

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how do the voids get there in the first place?
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