Is there a need for peel ply fabrics when infusing?

General Composites Discussions Composites Talk
#1

When you guys have your tool setup and laminates layed down do you use any peel ply fabrics between the bag and the laminate or just have the release film? I’m not looking for that textured surface look.

I was initially going to learn how to do plain vacuum bagging but I think I have decided to go with infusion instead, seems much more productive and reliable. For vacuum bagging you need a whole ton of layers (laminate, peel ply, perforated release film, bleeder, and finally the bag. For infusion I would assume you only need a release film between the laminates and the bag, correct?

#2

release film is peel ply sort of. I just have my laminate, then peel ply, then flow media if any is needed, and finally bag

#3

…don’t forget hose, T’s and sprial wrap or tubing that has been notched…

#4

Thanks guys, typically when making CF parts, is there any need for flow material? I plan on using 2twill 3k ~6oz fabric. When would you need flow material? when there are only a couple layers of CF or when you have a part with 20-30 layers? Or does it not depand the # of layers but rather the nature of the woven material?

#5

Whatever your infusing try using flow media over most of your part then watch how it infuses and adjust the flow media from there. You can normally reduce the amount quite a bit as you gain in expierience.

Baz

#6

the flow media in this case would be layed on top the final layer of CF correct?

I have a bit of trouble visualizing/understanding how the flow media works. It seems logical to me if you place a material in the mold with the rest of the CF that has a higher flow rate, then the flow medial will wet out first and allow the path of least resistance for the resin, leaving the CF dry? What am I misunderstanding?

#7

It all depends your laminate how much you need and you will gain that with experiance. I have some parts that have to be thick that I can use a ton of flow media. Like this hood below. The blue is the flow media

This particular part I only use about 20% flow media for the part. It is green in this pic. The blue under that is my peel ply.

#8

I see, but what wets out the rest of the CF, if the flow media is of lowest resistance for the resin to flow, what says you won’t have dry areas in the carbon?

#9

both those parts are 1 layer carbon and 1 layer continuous strand mat. Using that allows the resin to travel through the part

#10

ok! but what happens if you have a part that has very many layers of CF, say 20-30. (Somewhere down the road I want to build a subframe for my motorcycle) How would infusion work with this setup?

#11

that is a hella thick laminate! I have never done a laminate that was thicker then 6 layers of carbon. I use a lot of flow media, but you don’t want the resin to run so fast or you will not fully saturate and that will create a lot of little air bubbles too

#12

OK now I think I get it, you need flow media to allow the resin to be dispersed at an appreciable rate, while at the same time allowing the rest of the layers to be wet out. If the flow of resin is too high then you risk not wetting out all of it. if it is too low then you risk curing/geling before the entire part has infused!

Thanks for your help.

#13

yeah, but when it goes fast it will still saturate but it will not saturate evenly. The top layers will saturate first then the lower layers. If it is too fast then when the lower layers saturate it dispense trapped air as well and that stays in your laminate rather then in the front of the infusion. I hope that makes sense

#14

Yes thanks.

#15

You would want to do several infusions untill you reach your desired thickness.

And use heavy oz cloth, like 12oz or 19oz depending on conformabilty.

Another way would be to use water soluable tooling and a mix of cloth and CF tape.

One way or the other thats going to take an unreal ammount of time and planning.

#16

It will be a big project there is no doubt in my mind about that. Do the heavier fabrics wet ot easier?

I guess I will have to do my own experimentation with # of layers and thickness and how they wet out, and how many infusions it will need.

#17

And if you do several infusions, you need to use epoxy resin or they layers will shrink with each infusion and could easily disform your part

#18

Yes, I have not even considered anything other then epoxy.

#19

You should look into interlaminar flow media to help with wetout of thicker laminates. How do you figure 20-30 plies of reinforcement?

#20

If this part has 20-30 layers of carbon, then its sure going to be expensive and heavy!