Low tech infusion training exercise - Soric?

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#1

Hi All,
I have a small job to do & would like to try infusion on it & would like advice & critique on the proposed process, I have heaps of wet lay up experience & bagging in of foam/balsa core but I am keen to develop some skills & experience on this like on the job learning/training- theres enough “fat” in the job to cover a couple of mistakes but would rather not;) The job is to mold up a seat/engine box for over a Mercruiser power plant,

  1. build melamine faced particle board mold( very familiar with this for open molding & rapid construction of temporary tools)- like a set of steps with a return at xxxxpit sole & xxxxpit coaming- these to be extra wide for infusion plumbing & resin brake of peelply, there’s the panel at the back of your calves, the panel for the seat squab, the panel for back support also.All edges/corners radiused with polyester filler
    2)Wax & pva to molding faces, shoot gelcoat & also apply tissue skin coat
  2. build laminate stack maybe 300gm cfm/csm 450biax 300cfm/csm 3-4mm soricwhatever/laminate bulker 300cfm/csm 450biax 300cfm/csm then peelply then do I need perforated release film & infusion mesh or are these optional with Soric?
  3. install resin manifold(spiral?) down the middle of seat/measured center of laminate(the seat arrangement is about 2.2M wide & approx 1.6M top to bottom over the “steps” so only 0.8M to infuse each way)
    Install vac manifold to top & bottom return flange & tacky tape bag over the lot.
    5)pull vac & leak check, then shoot resin.
    PS: soric will be cut for the flat parts only & miss radii by 20-25mm or so, there will also be some relief molds(very simple additions to seat area for later cutout for access drop panels.
    This I am hoping will work for this part. Also there is some simple internal framing panels with all round flange/return that profile the internal dimensions of that stepped molding that will partition & act as a landing for a hinged engine access(I’d like to do these first but really need the “finished” internal dimension of the stepped molding).
    Any comments please esp’ on flow & fitting of bag to prevent bridging & resin flow on internal & external corners etc & vac integrity of particle board etc etc…
    Regards from Jeff
#2

Hi Jeff
You will need to seal the mdf with a layer of glass as you really need to ensure it’s air tight unless you envelope bag the whole thing, but be sure to have no sharps that could pierce the bag on the back side. If you do envelope bag it will take a little while to draw all the air out of the mdf.

You will need to run the soric over the entire surface (between laminates) or the resin flow will simply stop where the soric stops. Mind you if you are using cfm it works as a great infusion medium.

You do not need perf film or inf medium with soric.
You maybe ok with spiral wrap but I once infused onto a soric cored laminate with a silicone omega channel (silicone profile with a hole through the middle and a slot down to feed the laminate) and the narrow slot simply wasn’t enough surface area to feed onto the laminate and into the soric (probably didn’t help with the peel ply there either).FGI stock a feed channel called enka channel, about 100mm wide and place it on top of your peel ply. It can be a bit firm to get off.
Infused laminates are very prone to print!!
If anyone has tips to reduce print speak up now.
Often you will get print even after a tie layer has been applied.
I guess it depends a lot on the shrink of your resin.

#3

Thanks Brad, Sounds like my bags gotta land on the back of the tie layer as I’ll have framing on the back of the mold- maybe double tape the edges, on & off the tie layer, I’ll check with FGI on the enka channel, or maybe I’ll send the resin in along an outside corner. With the print, if its too bad I can block & buff the seen parts, as a lot of this item is unseen behind cushions etc so dosen’t matter so much. The print issues & having seen some dryish fiber in some infused stuff has put me off trying so far- but I think I have to move with the times & have a go! So starting on non structure critical parts before I commit to larger & more expen$ive risk.
Regards from Jeff

#4

Do you have some pictures? That would make things easier.

Anyhow:

The soric will be your flow medium. Which means the resin should have unrestricted flow into the soric, and the soric should be continuous throughout. If not, design your infusion strategy that it is, or add another flow medium. To help the resin through your corners, CFM might help.

Rule no. 1 with infusion: Your mould should be airtight. Really airtight. Taping on your (oversized) skincoat will run the risk of prereleasing the skin coat. Which means the skincoat should land on something bigger and airtight. MDF is not. Enveloping the MDF works, although constructions like corners are prone to damage, bending and cracking. This is a risk.

Soric needs at least 30 minutes to “settle” and equalise air pressure in the cells. Only after that it is advisable to do a pressure drop test.

Spiral as a runner works very well. If you choose the Colbond stuff, make sure you get the grey, not the white version. the grey version has twise the flow, and the envelope is much more permeable for resin.

#5

Thanks Herman, I’ll do a couple of tests on the melamine faced material. If I double tape, on & off the skin coat with vac in the “gap” between would that aid in vac integrity & help avoid pre-release?

Regards from Jeff.

#6

That would help, but it is not a guarantee.