Poor B side surface on vac infused part

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Poor B side surface on vac infused part

Poor B side surface on vac infused part

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Balazs Szikszai	B Balazs Szikszai posted 6 Years Ago HOT Topic Details
B Group: Forum Members Posts: 11, Visits: 74	Hi, I've been trying to vacuum infuse basalt fibre using the EC infusion kit with an existing vacuum pump. The mould is made from aluminium, and the A side seems to be coming out really well, but the B side (peel ply side) looks to be aerated between the top few layers every time. I recently changed the direction of flow to run along the part rather than across it, which was an improvement but its still not coming out right. I've tried this 4 times now with various directions and layups but I can't seem to get it to work properly. I wasn't able to order an EC epoxy as I'm in Australia so have used a local resin supplier. The vac pump pulls a strong vacuum, well under the -30inhg gauge minimum. I haven't degassed the resin. Is there anything specifically that causes this type of failure? The left one was resin flow across the part from left to right, and the right piece was flow from top to bottom, having to travel over the bends. Thanks Edited 6 Years Ago by bszikszai
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Hanaldo	Hanaldo posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	Was there a reason you were using basalt?
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Balazs Szikszai	B Balazs Szikszai posted 5 Years Ago HOT Post Details
B Group: Forum Members Posts: 11, Visits: 74	+x Hanaldo - 1/17/2020 11:39:54 PM Was there a reason you were using basalt? Basalt has a higher elongation and not as stiff as CF, so closer to S-glass in its properties. All this is better impact resistance. Basalt is also about half the cost of CF so would have been better from a commercial perspective. It would have suited my application a better, but I can probably make CF work too.
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Poor B side surface on vac infused part

bszikszai - 6 Years Ago

What type of resin did you use? I am not familiar with basalt fiber but what you describe sounds like air/vapor/gas problems. There are lots of potential reasons this can happen so it's hard to know....

explorecomposites - 5 Years Ago

Thanks Chris, I did actually stumble across your post late last night. I'm using an epoxy with a super slow hardener from a local supplier. Last time I finished the infusion I kept the pump on for a...

bszikszai - 5 Years Ago

Yeah - I have no idea where the idea of turning off the pump came from. To me that just sounds crazy! I don't know any situation where anybody I know/worked for/have talked to has ever turned the.....

explorecomposites - 5 Years Ago

Thanks for the advice, I'll give that a go over the weekend. My pump is not variable and I don't have a regulator so will probably use an AC manifold gauge and open the hot side slightly to reduce....

bszikszai - 5 Years Ago

Leaving the pump running and the outlet open is probably only going to draw resin away from the part and potentially leave the 'A' side looking starved of resin To ensure that the whole part is...

MarkMK - 5 Years Ago

Thanks Mark. I had the same thought about keeping the vac pump on after the infusion i.e. sucking the resin out. I guess it depends on whether its possible to drop it to a token amount. Its quite.....

bszikszai - 5 Years Ago

There's no need to leave the pump running after an infusion, it can't do anything anymore. Even if you did have a leak or moisture issues, the pump can no longer remove that air without removing resi...

Hanaldo - 5 Years Ago

The mould is made from an aluminium sheet, backed with a timber frame. My drop tests on this always maintain a strong vacuum so I'm fairly confident its not a leak

bszikszai - 5 Years Ago

Just to clarify the thing on keeping the pump pulling on the bag through the cure - it's like a syringe applying suction even if there is no clear air path. The laminate stays under pressure even if....

explorecomposites - 5 Years Ago

That clears things up a little, thanks. I've got a feeling (and am hoping) that the infusion speed and vacuum are the main problems here. I'm keeping my fingers crossed that with a resin break and.....

bszikszai - 5 Years Ago

I'm on Hanaldo's site here. To get reliable and reproducible results with vacuum infusion your bag needs to be perfectly airtight. And then you do not need the pump to apply pressure on the laminate,...

SleepingAwake - 5 Years Ago

Im a strong advocate for MTI hose. The first infusion I ever did was with a 2 to 3 inch resin break and MTI hose with great results. Simply lock down the inlet hose the moment all the peel ply is...

KLComposites - 5 Years Ago

MTI hose is awesome! I agree with KLComposites and have had great results with Proset too. Here's some evidence from the Easy Composites documentation on infusion that Google found for me. It...

explorecomposites - 5 Years Ago

Both methods work fine. Pump on and good resin break will work well, as will pump off on a sealed bag. It can be hard to get a great resin break if the flanges aren't that big which means the part...

Warren (Staff) - 5 Years Ago

I think it is also important to keep in mind that suction is not the driving force behind infusion (or even a syringe for that matter), it is pressure differential. When you draw resin through the...

Hanaldo - 5 Years Ago

So I set up another infusion late yesterday to try all of the changes, and so far, the results look promising. As suspected the resin had a huge amount of moisture to boil off and doubled in volume.....

bszikszai - 5 Years Ago

Update: The A side is completely flawless and there doesn't appear to be any aeration through the part, so gold star. BUT I'm still getting the surfacing on the peel ply side. Looking at it under ...

bszikszai - 5 Years Ago

So the theory is confirmed. The epoxy didn't seem to bond to the basalt fabric well enough and was being ripped off in places by the peel ply. Made up a CF test piece using the same technique as the...

bszikszai - 5 Years Ago

Was there a reason you were using basalt?

Hanaldo - 5 Years Ago

Basalt has a higher elongation and not as stiff as CF, so closer to S-glass in its properties. All this is better impact resistance. Basalt is also about half the cost of CF so would have been bette...

bszikszai - 5 Years Ago

Yeh sure, I know basalt well, I only ask because most people are using it for cosmetic purposes. I have had similar experience to you though, I find it's interlaminar bond strength very poor - I was....

Hanaldo - 5 Years Ago

There seems to be a pattern forming here! I've been speaking to some composite specialists at a university down here, and it was suggested that the issue might be related to fibre sizing (...

bszikszai - 5 Years Ago

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