resin infusion mold inside vacuum bag?

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#1

I just thought of this and was wondering if its possible… I have an openface mold which is fairly flat, less thne 6" high. Instead of using the tape and sealing the bag around the perimeter of the mold, is is possible to just set it up like normal except skip the double sided tape and bagging material and just put the whole mold into a vacuum back? theoretically if the bag is much larger it should accommodate for the contours of the part no? then insert inlet/out into the bag and proceed…

if this is possible it will cut down cost dramatically since you will not need all the sealant tape, baggin material, and if there is a leak it will be easier to find since only one side of the bag will have an opening (once the bag is tested to be leak proof…

Thoughts?:confused:

#2

Yes, I do this quite frequently…you still need to place and secure your feed and vacuum lines appropriately. Just leave enough loose bag to compensate for lack of pleats to get into tight spots if there are any.

#3

Commonly known as “envelope bagging”. If you do a search on this forum, more info will pop up.

a factor to consider is the backside of the mould. It should be relatively smooth, and not puncture the bag.

#4

To add on what Herman said yes you can do it but watch out for sharp edges and such. You’ll also have to check that every time you do a bag system like this because sometimes edges form over from the previous bag so you’ll need to sand them down and do a once over.

I do this for a mould that I originally messed up but salvaged it by cutting off one side i didn’t need. You can do this method on a flange-less mould as well.

#5

Yeah forgot to mention the sharp mold edge check, very important. On thing I’ll do is bond cheap clear vinyl tubing to the outer perimeter of the mold with hot glue. Split it down it’s length with a razor. Provides a nice radius edge that will not cut the bag under high vacuum and if damaged it tears off and is replaced easily.

#6

All of my parts are made this way. I got tired of buying so much vacuum tape, so I decided to do it this way… I wax the back sides of all of my molds so excess resin doesn’t stick. I also cut a piece of felt and place it on the backside of the mold, running up to the vacuum fitting- which is placed a few inches from the mold. I’ve never sucked up resin into my vacuum lines and my infusions run perfect doing it this way.

#7

Ah so Thats what “envelope bagging” is! thank you, knowing the proper term helps out a lot:D

thats a brilliant idea… thanks a ton!

#8

So you buy the airtech bags that have the seals already right? Like the ones listed here.

http://www.acpsales.com/Vacuum-Bags-Films-Peel-Plys.html

Have you ever used their “quick lock seals”?

#9

Yes. Quick lock seals are AWESOME and I use 6 mil poly bags. I buy the bags from this place:
http://www.poly-bags.com/c-1427-6-mil-clear-layflat-poly-bags.aspx?PageNo=4

#10

That’s pretty crazy. They’re USDA food safe too so that means if you have a vacuum machine you can store food in them too!

Have you ever had an issue with them breaking or bursting open under any circumstances? I don’t mind the whole “flange, tape, bag” part but this seems like a great alternative too.

#11

They very probably are polyethylene, so no special heat resistance, and depending on quality they might be a bit microporous. But indeed an interesting option.

Indeed great for food. And you have very nice grain fed sirloin steaks over there. (we don’t. Most beef is crap. And now there is a scandal about horse meat miraculously turning into beef… (sorry, Texans))