Looking for guidance on resin inlet placement

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#1

I’ve begun to experiment with resin infusion to build a strong and light weight aero component for my race car. I need some guidance on placement of the resin spiral wrap inlet(s) to help speed up the infusion process. My last attempt failed before the part could be fully infused.

This is a the fiberglass/epoxy on corrugated plastic signboard prototype:

The following picture depicts the process after 1 hour. The part is resin infused with spiral at one side and vacuum port and spiral on the near side to provide shortest path for the resin. I kept feeding the part using smaller and smaller batches of resin to avoid exceeding the gel time. I finally had to stop after 1.75 hours with 20% left to go when things pretty much came to a halt and my last batch of resin exothermed.

My setup is as follows:

[ul]
[li]3CFM 1/3HP 2 stage pump and catch pot (29.7" Hg)[/li][li]Mold waxed,[/li][li]PVA,[/li][li]laminate lay-up (2 x 8.9oz plain fiberglass, 1 x 3mm coremat Xi, 2 x 8.9oz plain fiberglass),[/li][li]Peel ply,[/li][li]Resin infusion mesh,[/li][li]Vacuum bag.[/li][/ul]
Is there a more appropriate placement of the resin inlet(s)? I was thinking of adding 2 additional ones (the two red lines below) to help keep the infusion time to under 1 hour. I would really appreciate some feedback. Thanks in advance.

#2

What resin system are you using? viscosity?

I would place the resin inlet down the center and apply vacuum left and right of it. With the righ infusion system you could easily infuse in 15 minutes.

#3

There are so many options:

From left to right. (you tried)
From middle to the two sides (already a lot faster)
From the two sides to the middle (lots faster)
From the perimeter towards the centre (really fast)

These are options which do not involve timing operations like closing one valve, and opening another. You suggested a cascading system, which also works, but slightly more of a hassle.

I would use the perimeter towards centre approach. I know leak paths in the sealant tape could spoil my infusion, but I feel confident I can keep things airtight over there. (easy to fix during infusion as well)

#4

I’m using Miapoxy-100 with their slow hardener Mia-95 (38 min gel time). Viscosity is listed as 800.

That would definitely cut the time time down to under one hour and I would only have to deal with one resin port. I’m still worried that the part will still need to infuse for over an hour.

#5

Some great suggestions. It’s a pity that these tests are so expensive. Live and learn as they say.

One quick question … I waxed and applied PVA to the whole mold including the location where I placed my bagging tape. Is that standard practice? Sure helps in cleaning the mold up afterwards. Down side is I got some small lifting of the bagging tape in a 90 corner that caused some leaking.

Thanks again

#6

I used to have a similar issue with a large part. you can place enkafusion filter jacket ( http://www.fibreglast.com/product/EnkaFusion_Filter_Jacket_1400/Vacuum_Bagging_Vacuum_Infusion) to increase resin flow. I would place it in the center and vacuum lines on left and right side. you can place a T fitting in the center of the jacket and no need for spiral wrap.

#7

Thanks bryanha. That looks like an interesting option for me to use.

#8

Visosity is the biggest reason your infusion is so slow. A good infusion epoxy is Gurit Prime 20ULV, visocosity is 150cps. You could infuse the same way you are now with this reason it would probably take 30-40 minutes

#9

Good info. That is a huge difference in cps. Worth giving a try.