Infusion issues, loss of compaction?

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#1

Im having issues with an infusion that Im doing. The mold is for an ice hockey goalie mask. I dont have any pictures but the general shape of it is a wedge. I am using spiral wrap all around the perimeter flange and have my resin inlet at the center of the mold.

The issue that Im having is that I seem to be losing compaction right at the center of my mold. The laminate I have is the same through the whole piece, however the layers near the resin inlet are not being compacted as much as the perimeter. The laminate properly infused should have a thickness of about 1/8 of an inch. However the laminate gets thicker the closer it gets to where the resin feed is.

I do not have any vacuum leaks that I can detect. The only thing I can think of is that my resin inlet hose is too big. I never had a problem with this before, but excess resin seems to pool right at the resin inlet before the resin can spread out to the rest.

Im using a 3/8ID inlet hose which I think might be causing the issue. Would an inlet that is too big cause issues like this? I wanted to see what other guys thought before I tried this with a smaller inlet hose.

#2

Two things you can do.

1: Place the resin pot deeper than the part, about 1 yd, this will work like a vacuum on the resin pot so that your resin flow is reduced.
2: clamp the resin feed a bit earlier so that the pooled resin can dispense in the non saturated fabrics. You need a feeling for that.

#3

A smaller inlet line could be used as well to slow the infusion.

#4

So I guess the consensus is that the resin flow into the part has to be slowed down. I have a 1/4" line so Ill give that a try.

#5

Another option is rigging the inlet hose with a T-piece and a valve, then connected to the vacuum overflow vessel.

During infusion, keep the valve closed. After infusion, clamp off near the resin pot, then open the valve. Now you have an extra vacuum point on the part, which will draw out excess resin.

A large infusion I did that way resulted in 2300 kgs of resin in, and 130 kgs of resin out.

#6

^^That’s clever…I like that!!

#7

So an update on this.
I tried infusing using a small (1/4") line for my resin feed. I also used a 2 hour pot life epoxy to make sure that the resin gelling too early isnt an issue.

I did my layup but Im still not getting the same amount of compaction all around.
Ive never had this issue before and I cant seem to find a solution. I dont get resin pooling anymore but the middle of my part still ends up being much thicker than the perimter of the part.

Would using a silicone intensifier be the next step? Can that even be done with infusion?

#8

Infuse less rein or work with vacuum on the resin pot. And with less resin I don’t mean slower, I mean close the feed line earlier.

#9

Im already clamping the resin feed line well before the resin front reaches the edges of my part. Any sooner and I dont think the entire part will infuse.

#10

whats vacuum level are you getting? and are you sure that your part is reaching the same vacuum level as the pot? Try gauging your part at the inlet before infusing. I bet anything your part itself is much lower

#11

Ill try again and stick another vacuum gauge right onto the resin feed inlet before I infuse.

#12

You’re resin inlet is in the center of the part?

#13

Yes, I have the inlet in the middle and spiral wrap (or MIT hose) all around the perimeter.

Im going to stick a vaccum gauge on the actual inlet hose and see if that is a problem.
If not, Im thinking of putting the resin inlet on the perimeter and the vacuum in the center to see if that makes it better.

#14

posting a photo of the actual mold and setup could quickly identify the problem

#15

A pic would help to see why the resin is pooling, I imagine because the resin inlet is in the center and being forced up the sides of the helmet that this would be a big part of the problem, I think I read previous about slowing the infusion down so the travel matches the inlet feed rate but you’ll be there for sometime and risk it gel’ing potentially based on the type of hardner being used.

If we could see the mould, I still think you should try one side to another of infusion versus center up.

#16

SLS,
I think thats the problem. This is the new helmet design that I spoke to you on PMs about. It’s a much narrower mask, more like a V shape than a U shape so Im thinking that is why Im having problems. I’ll try to post pictures later. I made this mold with a very small flange (2" or so) because I was using MTI tubing, I may have to remake the mold with a larger flange so I can infuse end to end or side to side.

#17

Agreed.

Try a lateral infusion with your inlet and feed outside of the part area of the mold.

2 inches of flange should be enough albiet tight. We just built a part from somebody elses open mold with barely 2 inches of flange. We actually did a double bag with the second bag from the back side of the flange.

#18

I’ve been afraid to say that double bagging could help. :smiley:

#19

Easy going:) We will fix the problem without making a new mould. You will not fix your problem by double bagging or reverse infusion. It is a resin flow problem. Post some pictures and than we will see.
Resin pooling means you have too much resin in your part, and that problem can be fixed, I promise.

#20

We’ve done similar type work, a little different application but the initial idea was to run the inlet center and pull the resin to the top, it just took so damn long…this was for the mining industry but the shape was like a helmet.

We switched it and went from one side to another on infusion, worked fine…we just ran the spiral wrap nearly half the circumference on the feed side, it shot all the way, no dry spots, still make them, that is how we do it.

If you want PM for more details.