carbon wet-out consistancy issues.

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carbon wet-out consistancy issues.

Author	Message
Matthieu Libeert	Matthieu Libeert posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 955, Visits: 3.4K	as far as I know it is just adding some extra resin making it more resin rich = less pinholes Matthieu Libeert Founder MAT2 Composites X Sports website: www.mat2composites.com
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Hanaldo	Hanaldo posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	Definitely let more resin in, that screams of starvation to me. Just because the part appears fully wet out from the back, does not mean the resin has saturated the surface. Don't be scared to let excess resin in. You'll actually be amazed how much of a difference it will make to surface finish without really affecting the final weight/strength of the part.
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20_rc51_00	20_rc51_00 posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 95, Visits: 548	my technique, 1) use degassed resin. (pulling bubbles through en entire length of infusion doesn't make logical sense, especially once you clamp off and there are still bubbles but not as much resin velocity/flow toward the vac side.) 2) warm things up 3) lowest visc resin possible for desired physicals 4) infuse at a pace that doesn't cause bubbles/air inclusions in the mesh media. Even if you have totally bubble free resin in your pot but infuse at a rapid rate you will trap bubbles in the mesh..., also you can't expect the stack of reinforcement to wet out at the same rate as the rate of flow laterally across the part. (risk dry spots) 5) include air pathways for parts of the mold that infuse more slowly or are tricky areas (this is where the MTI hose shines from my theoretical understanding of it. it provides uniform vacuum pull from all directions even when certain areas have fully wet out and reached the periphery. 6) don't lay the infusion mesh all the way to the periphery. leave a couple inches for it to infuse just though the reinforcement, this also helps with the scavenging of bubbles that might need to move through the part still. 7) the cross section area of your resin inlet hose given resin viscosity will be very restrictive even at full open if you are infusing a very broad part. might need a couple inlets or a larger diameter. remember it is the atmosphere sitting on top of your resin pot that is pushing the resin through up the hose and through the part.
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Superleggera	Superleggera posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 15, Visits: 399	What are peoples thoughts on regulating the vacuum with a control valve when infusing? I always infuse at full vacuum but I've been looking at the SMC valve on EC (https://www.easycomposites.co.uk/smc-vacuum-regulator-for-vacuum-bagging) and the notes state that a 20% vacuum is a good starting point!
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20_rc51_00	20_rc51_00 posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 95, Visits: 548	you always want the pump pulling full vacuum, it's just the resin inlet that needs starving off to limit the rate of resin inflow.
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Superleggera	Superleggera posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 15, Visits: 399	That being so, what use is a vacuum regulator valve?
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ChrisR	ChrisR posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 363, Visits: 3K	when using certain cores you can't pull a full vacuum otherwise it crushes, you use the regulator to control it
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Hanaldo	Hanaldo posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	Or for vacuum bonding when you want enough pressure to hold something in place but not so much that it can distort the shape of the object or shift etc.
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jono	jono posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 11, Visits: 63	interesting you bring that up. i was wondering (as i dont have a gauge) if i could potentially be pulling too much vaccum? i did a wet layup the other day in a different mold and then did the release film/breather typical combo. there was definatly enough resin in there wand was fully wetted out, bagged it, didnt think anything of it. pulled it out the next day and dry as hell just like my infusion issues. definatley investing in a gauge now but id like to know if it sounds like too much vaccum, especially from people that know more than me...(everybody)
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20_rc51_00	20_rc51_00 posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 95, Visits: 548	if that last one was a vac bag and not infusion Id say you drained off too much resin with the bleeder. The dry problem is not an issue with vacuum imo. its an issue with resin starvation/saturation whcih comes down to controlling the rate of resin infusion speed or amount of resin bleed off into the breather layer(with vac bagging). The former addressed with slowing the resin inlet for a given resin viscosity and the latter with changing the amount of perforations in the release and/or reducing the thickness of bleeder/breather layer that that when it does saturate it isn't so thick that it takes up all the resin. Could it also be that your carbon has a coating designed for a certain type of resin and your current resin is phobic to that coating?
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