Infusing thick laminates

General Composites Discussions Composites Talk
#1

Hi Guys, Stumbled across this forum and have been reading some great stuff on here. Now time to ask for some advice…

I’ve been having trouble infusing (relatively) thick laminates and I’m not sure why. Biggest problems I have are with +/- 45 fabrics (nonwoven). The epoxy resin I use (~300cps) is OK and eventually infuses but there is intially some build up of resin near the resin inlet.
The polyester and vinylester I’m using is probably too viscous (1200 and 1300cps respectively) for infusion and I get prety much nowhere.

I guess what I want to know is how to get the epoxy infusions going faster without the pooling of resin under the bag at the inlet end.

I’m using greenflow to connect resin and vacuum to the ends of the laminate stack on a flat glass plate mould.

Any advice would be great, cheers.

#2

BTW, was trying yesterday 8 layers of +/-45 600gsm E-glass.

#3

Do you work with a flow media? Have you regulated the resin inlet? May be it is helpful to post a picture.

#4

Here is a photo of 3 setups on one glass plate (normally would only have one and just one stack).
http://i1208.photobucket.com/albums/cc378/ryanagd/IMG_0523.jpg

I use greenflow to connect inlet and outlet to the fabric stack. Resin flow can be controlled using the valve at the inlet end.

#5

Where is your bucket elevation wise, compared to your bag? If you have resin pooling, then it sounds like maybe your bucket is above, or at the same level as the bag. Drop the bucket down below the bag.
Also, is that the only issue you are having? not much of one, since you can just machine it off. Maybe add more bagging, and tuck it under the tubes, make sure there is no bridging on the inlet side, or offset the tube an inch or 2 from the part, and just make sure you have flow media from the inlet to the part (and so on)
Also, if you are only using one glass plate as a mold, use peelply to connect the vent to the part, or place the vent spiral right on the part.

#6

My resin container is above the bag, I will put it to below to combat the pooling. Cheers, should’ve thought of this myself.
The problem with the pooling was that it pooled rather than infused into the laminate and kinda sat there.
The infusion speed is slow in the type of laminate mentioned above, that is the main problem really as the epoxy I use starts to exotherm after about 30mins at ambient temp.

Not using any spiral tube, only greenflow to connect the resin to the part.

I uploaded a photo link with my last post but moderator doesn’t appear to have approved it yet…

#7

Just tried a new setup with the resin below the bag etc. No pooling this time, but it still went very slowly.
This was 2 layers of 800gsm +/-45 glass fabric (500x500mm). In the last photo you can see where the flow front got to at different time intervals.
The resin started to exotherm at around 23mins after mixing, so I put it in a bucket of water and stirred it a bit. It really started kicking off around 10 mins later and got up to 190*C with a bit of smoke!

Setup photos:
http://i1208.photobucket.com/albums/cc378/ryanagd/12102011377.jpg
http://i1208.photobucket.com/albums/cc378/ryanagd/12102011381.jpg

Flow front photos:
http://i1208.photobucket.com/albums/cc378/ryanagd/12102011383.jpg
http://i1208.photobucket.com/albums/cc378/ryanagd/12102011385.jpg

#8

I can see the picture.

Change 3 things:

-1. The resin pooling is due to the resin stock being above the infusion level. Bring it down. You already found that out.

-2. Your laminate has a very low permeability. You need the infusion mesh (greenflow, although it is too fast for my liking) to go over the complete laminate. But stop it some 2" short of the laminate on the vacuum end. On larger projects, increase this size to 4"

-3. Instead of using greenflow to attach the laminate to the vacuum, use peelply. Keep the vacuum port some 4" away from the laminate. The air will flow through the peelply, do not worry.

And make pleats, bridging kills infusions.

#9

Ryan where are you getting you hose stuff from with valve in your pic

#10

Thanks Herman.

I’m using steel RICs, waxed so cured epoxy doesn’t stick, will air still flow ok?

How many pleats do I need for a 600x600mm infusion (as in the picture) of a flat plate?

#11

Most of the hose is from Tygavac, other bits of hose to join valves and RICs are from ColeParmer. Valves are from a gardening shop (checked for leaks).

#12

Sure, why not?

How many pleats do I need for a 600x600mm infusion (as in the picture) of a flat plate?

Everywhere where you have a thickness variation.

So if you have a 60x60 cm test area, with 40x40 cm laminate, there should be pleats on the edges of the 40x40cm. They do not need to be large, just 2-3 cm is all you need.

#13

Yeah, there is no reason not to use 90% coverage of flow media, it will speed the infusion, and as long as you stop the flow media and inch from the end, the bottom will catch up with the top of the stack. You can add peelply as herman mentioned to the vent side. It will allow the resin to flow to the end of part, and then slow down once it hits the peel ply, thereby making sure all voids in the part are filled. I do not think you need pleats for something that thin. The bagging should conform easily enough. If you notice any bag stretching over edges, just add 2 tiny pleats on each side, just to give an extra amount of bag to conform.
I think that covers the main issues. Resin below part, flow media covering inlet until 1" from EndOfPart, and pleats of the part thickness is getting large (which, I can not see any racetracking in your pics, so you are good)

#14

Thanks herman and riff42.
I will try these suggestions in an hour or so and post pics of how it goes.

I forgot to mention that for this infusion (and the one yesterday) I am using peel ply on both sides for the desired surface finish. Will this have any effect, detrimental or otherwise?

#15

Before:
http://i1208.photobucket.com/albums/cc378/ryanagd/13102011399.jpg
And about 6 mins later:
http://i1208.photobucket.com/albums/cc378/ryanagd/13102011400.jpg

Much better, thanks guys.

Do you think doing it with these improvements will mean I can use the previously mentioned polyester and vinylester resins or are they still too thick in your opinion(s)?

#16

peelply won’t hurt anything.
as for the resin, are they infusion resins?

#17

the viscosity of the polyester and vinylester resins you mention make me suspect these are hand laminating resins. These are totally unsuitable for infusion, as their rheology is totally wrong. They will infuse a bit, then stall completely.

Infusion resins usually are unmodified resins, with a viscosity of 100-500 cps. (hand laminating anywhere from 1000-4000 cps, depending on method and speed of measuring)

#18

I suspect they are both hand laminating resins, which is a little annoying, I’ve got loads of it!

Demoulded panel, seems good. Some dry bits on the underneath though near the vacuum end. Could this be due to not enough release agent (I ran out of Frekote and some resin stuck to mould)? Or is it more likely an infusion problem? See below pictures, thanks.

Top:
http://i1208.photobucket.com/albums/cc378/ryanagd/14102011406.jpg
Bottom:
http://i1208.photobucket.com/albums/cc378/ryanagd/14102011407.jpg
Dry patch on bottom:
http://i1208.photobucket.com/albums/cc378/ryanagd/14102011408.jpg

#19

Does not seem to be mould release related.

What was the infusion time?

#20

Infusion time was about 6 minutes when the flow front had got to the end of the laminate.