First Time Infusion Questions

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#1

Going to try infusion for the first time this weekend. Have learned much from this group over the last few years but a couple of setup questions remain.

The attached photo shows the mold shape, part outline and intended placement of the infusion materials.

New mold sealed with Frekote FMS and using Frekote 770 release agent.

Layup schedule is 3 plies of 6 oz 2x2 twill CF, peel ply, perf ply, SL200 bag. Resin is Proset 114/211.

Questions-

  1. I found on a test mold that the bag sealing tape does not stick well at all to the mold once treated with release agent (I guess it is doing the job). Will the tape still allow pulling the necessary vacuum even though it is not aggressively stuck down to the mold?

  2. I planned to use green infusion mesh but in looking at the setup I am thinking that the mesh is not necessary. With a relatively small infusion path I was concerned that it would proceed too quickly. Also don’t want to risk imprinting the part as the face surface must be good cosmetically.

  3. Comments on the feed/MTI tubing placement? I considered a central feed line to a full MTI perimeter but similar to above was concerned about imprinting the part.

Thanks in advance for your input.
Bob

#2

I would use the mesh. I would also pull from one side for infusion to the other side for MTI hose or basically shortest distance. Maybe bottom to top. MTI hose should only be touching brake zone ( peel ply after the part 1-2".

#3

Thanks for the response Ro Yale.
I took another look at the setup and will change it to pull from one side as you suggest. Have decided to polish the mold once more so will have to wait a couple of weeks to actually try it but will certainly post the result. With respect to the sealing tape on the Frekote do you think that will be an issue?

Thanks.
Bob

#4

You can test the tape adhesion without any infusion. Just use a piece of cloth and try pulling your vacumm to see if the tape holds a seal. I don’t ever have a problem with it but I don’t know what tape you are using.

#5

Yes. If your tape pulls up while the infusion is happening you will have porosity and basically have wasted your time.
I used frekote and now do zyvax. But both are semi permanent releases.
You should not put release agent where you intend to have sealant tape.
You should mask off the mold except the perimeter, strip the release, put down flash tape, put masking tape over the flash tape to protect from the release agent, then reapply your release. Or strip the whole mold and start over.

#6

Just wipe the outer 10-15mm with acetone to get rid of the Frekote. Frekote seems especially bad for sealant tape, other high slip semi-perms dont struggle as much.

In future it is easier to mask off the perimeter before you apply the Frekote.

#7

I tested the ability to adhere the tape to the Frekote last night. It sticks but certainly not well. Will wipe the edge before applying the tape as suggested.
I am assuming that the infusion process with MTI hose does not result in epoxy reaching the sealing tape? Otherwise it would destroy the mold?

#8

Not really, theres still every chance the resin will reach the sealant tape. This is why I try to only leave the outer 10mm or so, as generally this is enough for the tape to grip and seal to, and normally there is no unreleased section extending beyond the tape.

It’s not super critical though, a little bit of resin bleed sticking to the perimeter of your flange will hardly destroy the mould. The worst that happens is those bits can be quite sharp and pierce the bag next time you use the mould, so I normally just take the sharpness off them with a razor blade.