Safe to remove from vacuum

General Composites Discussions Composites Talk
#1

Hello,

I need to make a couple of parts quick. When is it safe or the least damaging to remove a part from vacuum? It will still be on the mold and wrapped in peel ply just no longer bagged.
I am going to be making CF tubes with an aluminum mandrel. I am thinking two full days cure in vacuum then the rest of the week out of the vacuum with temperature constant through out. This problem came about because I need to make 12 things but only have 8 vacuum connectors because I thought that would be enough when I first got into DIY composites . I am fine with the tubes being stronger than lighter but I still want that balance of both.

Alternatively is it possible to make up a tube vacuum bag it, then half an hour later open the bag up and add in a second tube? I got plenty of materials just not enough vacuum bag connectors and valves.

thanks,

#2

depends on the resin system you have choosen, check the technical data sheet or call the manufacturer. Two days is probably atleast a day+ longer than it needs for vacuum, as far demolding it would depend on the resin. Post curing would be recommended.

#3

Just a thought, but you also don’t always need connectors for vacuum bagging. You can run a tube/hose under the bag at the flange (extra bagging tape) and use some flash tape to attach breather to the end and overlap that with your current breather.

-Mike

#4

Thanks. The resin i have will cure to solid in about 12 hours and max strength in about 5-7 days. I have always left it for about 10 days under vacuum because I could before. I just needed some reassurance to make sure it wouldn’t go bad after removing the vacuum. It will still be in the bag just not under as much vacuum.

I’ll keep that method in mind for not using vacuum connectors if I get the chance but it will be about half a day before the next part is ready to lay up.

#5

1: Like Frost said, you don’t NEED a ‘connector’…as long as there is a tube, airflow, and vacuum, you are solid.
2: Check with the resin manuf. If it cures in 12hr, then you do not need vacuum past that. If it’s still gel, or even soft, I would keep it on longer. You can also speed the cure with heat somehow (oven, blankets, rotisserie in the sun…)
3: Just make sure the tubes are safe until they are fully cured (5-7 days as mentioned), or post-cured. If you make a ton of tubes, stack them diagonally on teh wall, the weight of them might change the shape and bend them slightly. But once the resin is cured solid, no need for vacuum at all.