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carbon wet-out consistancy issues.
carbon wet-out consistancy issues.
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carbon wet-out consistancy issues.
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jono
jono
posted 10 Years Ago
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hi all, i'm having issues with the final part not wetting out enough consistently. I am using the same mould, same layers, same resin and temperature conditions. absolutely no leaks in the bag and obviously the same vac pump. it visually appears to infuse at the same rate every time but only 1/3rd of the time it's actually fully wetting out the weave. it seems to be luck of the draw for me? i'm using a low viscosity resin, pulling a vacuum for at least 40 mins before infusing. i've tried clamping off the vac line and resin line like the easy composites tutorial, i've also tried allowing the resin to almost empty the pottle and only clamping the resin line and allowing excess to reach the catchpot and letting it cure wit vaccuum pump going. also moving around the resin feed/vac lines. i honestly have no idea what the cause is. would appreciate any help here.
this is what my parts come out like 2/3 of the time.
yet sometimes my parts come out perfect like this (same exact mould)-ignore the traces of clay on it-
any idea what could be doing this? i'm doing a fully dry layup, no glue or gel coat (its a brake duct) should i perhaps consider brushing/spraying a fine layer of resin down and allowing it to almost fully cure to a late stage of tack and then layup/infuse?
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ChrisR
ChrisR
posted 10 Years Ago
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Before you read the below, understand this is not supposed to offend (therefore please do not) but this is from MY experience with infusion:
I infuse at FULL vacuum, the volatiles boil off thing (from my experience) is complete <insert expletive here> and does not apply to epoxy anyway.
Yes, if you put a pot of poly resin in a vac chamber and pull a vacuum then yes they can/will boil off as the boiling point is lowered and the thing won't cure. I've used polyester infusion resins quite a few times with success every time, the only instance I've had with something looking like "boiling off" has been when the mesh has pierced the bag and it's letting air in.
Control the flow front with the type of mesh, barriers/dams/inlet/outlet positions and cutting off the flow by clamping - some (many) will probably disagree with me on this following point but hey...
By controlling the flow using the above there is absolutely no reason
I have come across
to infuse at anything other than full vacuum (or as close as you can get)
.
Pull the vacuum for (depending on size and layup of course) at least 30mins, do a drop test, only infuse when you know for sure the bag is sealed.
Control the temperature of the resin, mould and fabric, just a few degrees change with some resins can change their viscosity considerably.
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carbon wet-out consistancy issues.
jono
-
10 Years Ago
[quote][b]jono (04/03/2015)[/b][hr]hi all, i'm having issues with the final part not wetting out...
fgayford
-
10 Years Ago
I noticed you're from NZ, We are from Australia, and funnily enough, we are having the EXACT same...
JustJDee
-
10 Years Ago
Hi buddy, hello everybody, Shelby Cobra at which you worked is awesome! There are several reasons...
FLOR
-
10 Years Ago
Before you read the below, understand this is not supposed to offend (therefore please do not) but...
ChrisR
-
10 Years Ago
thanks for some very good points. i have not been slowing down the resin at all. i will definiatley...
jono
-
10 Years Ago
From my albeitlimited experience you shouldn't need to infuse in an oven with that ambient temp. I...
FLD
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10 Years Ago
so i should also clamp off the vac line first before the resin feed? i may just try that. i have a...
jono
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10 Years Ago
We tried clamping off the vac line first then waited a bit before the feed line, and indeed it did...
JustJDee
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10 Years Ago
i wonder if it has to do with the part and bag relaxing and equalising out somewhat that just allows...
jono
-
10 Years Ago
as far as I know it is just adding some extra resin making it more resin rich = less pinholes
matthieutje65
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10 Years Ago
Definitely let more resin in, that screams of starvation to me. Just because the part appears fully...
Hanaldo
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10 Years Ago
my technique, 1) use degassed resin. (pulling bubbles through en entire length of infusion doesn't...
20_rc51_00
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10 Years Ago
What are peoples thoughts on regulating the vacuum with a control valve when infusing? I always...
Superleggera
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10 Years Ago
you always want the pump pulling full vacuum, it's just the resin inlet that needs starving off to...
20_rc51_00
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10 Years Ago
That being so, what use is a vacuum regulator valve?
Superleggera
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10 Years Ago
when using certain cores you can't pull a full vacuum otherwise it crushes, you use the regulator to...
ChrisR
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10 Years Ago
Or for vacuum bonding when you want enough pressure to hold something in place but not so much that...
Hanaldo
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10 Years Ago
interesting you bring that up. i was wondering (as i dont have a gauge) if i could potentially be...
jono
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10 Years Ago
if that last one was a vac bag and not infusion Id say you drained off too much resin with the...
20_rc51_00
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10 Years Ago
hm. i did double up the breather layer when i vac bagged the parts..... :ermm:
jono
-
10 Years Ago
Ive had very mixed results wet lay and bagged using full vac, the best parts ive made have been...
VVS
-
10 Years Ago
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