infusion setup help

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#1

Hello!
I plan to try some infusion work and would like som input, it seems like there are quite a few things that can go wrong if you don’t know what you’re doing.

I am doing tubes, 40 mm in diameter and 60 cm long. You can see a sketch of my infusion mold in the picture. I plan to use a pressure bladder inside the mold, simply a cut road bike tube with release added.

One inlet, one outlet. Edges of mold will be sealed off with a double row of mastic tape. The mold will not be transparent, I will cut the flow when epoxy meets resin trap.

Will it work like this?
would you do it differently (how?)
Do i need some flow media?

I’d really appreciate some input!

Cheers /Lars

#2

I have no idea what you’re doing!
Are you pressure molding or using vacuum?

#3

as long as it all seals, and your tube bladder (good idea too!) works…sounds like it should work. Not sure how you will be infusing and pulling vacuum on the part though…shoving distro media in the ports?

#4

why are you removing material from the backside of the tools? Save lots of machine time and leave it stronger.

#5

I will be using vacuum for this, I should be able to get some extra pressure from the bladder also. My main concern is flow as i havent’ tried any of this before and will not see the progression through the mold.

I am thinking of wrapping some breather fabric around the bladder all the way to the ports for better flow. What do you think?

The mold will be built from glass fibre and epoxy, the pic is just from a 5 min. sketch i did, the back side of the mold halves will be reinforced with wood or metal inlays and addtional layers on top of that

//Lars

#6

air pressure in the bladder is going to be important factor. Too much pressure and resin will not flow, too little and, well you know what then.

60cm length… your going to need flow medium to reach 60cm or even 1/4 that distance.

You also need to make sure the flow medium will not puncture the bladder. I don’t know what material your bladder is or the thickness of it.

You will also need peel ply or perforated release ply between the flow medium and the laminate materials.

Make sure you are pulling at least 26hg.

TET knows more about this.

#7

tried the infusion and it went straight to hell! The mastic i used for sealing got sucked into one of the ports, also the bladder punctured due to too high pressure.

Have built a see-through mold now that i can see what happens in the infusion. Might do a video of the infusion later if everything goes well…:cool:

#8

thought of something. Why not do a wet layup, and then use the pressure bladder to squeeze out the extra resin? Maybe add a few tiny vent holes in certain spots.

#9

If I were doing this, I would start with a slightly pressurized bladder, done the infusion, then increase bladder pressure after cutting off resin flow. In my experience, tubes are trickier to infuse than flat parts, and the added squeeze from the inner bladder might prove to limit resin flow too much.

#10

good point! the permeability of the fabric will drop. Though, you would need to pressurize the bladder anyway to wrap the fabric around it, right?

I still say, go with prepreg and be done with it :wink:

#11

have used a plastic tube inside the bladder so it is straight and nice to roll the fabric around before putting into the mold. tried a test infusion yesterday using oil instead of epoxy to see the flow, it worked ok.

#12

why do you wanna make your life harder with these complex molds and bladders? just using aquapour and heat shrinking tape will be more cheap, easy, fast, and risk-free.

#13

See your point about complex molds and such, a lot of work to get the part done!

In my previous attempts if you do something like 8 layers at once on a mandrel there will be excess fabric that wants to wrinkle when you compress it.

Therefore it seems better to expand the fabric in place in a hollow mold, that way the fibres stretch out nicely.

Haven’t tried heat shrink tape but plan to do so soon, is it easy to get uniform compression?

#14

Posted by - riff42 - I still say, go with prepreg and be done with it

I would second that!, What temp. can your moulds take?, I have been making pre-preg tubing for many years now with a low temp. pre-preg and I use Expancel to expand this against my tooling - see my post Man. 32mm OD Tube in Showcase, give it a try if your moulds can take the heat, good luck.

#15

are you still trying to attempt this project?