I have done vacuum infusions before, but since a month ago, randomly when I start heating some set up to let the resin cure after the infusion (epoxy), the tacky tape seems to melt and I lose all the vacuum. At the beginning, I though that the tape had a defect, so I return it and bought a more expensive one, that could hold until 300°C (from [FONT="]Tygavac / UK ). Today, after the infusion, it happened again and the tape collapsed at 120°C, so I lost all the vacuum. It seems like the tape is melting on the middle, so next to the resin inlet and outlet, it creates holes which destroy the infusion. Did someone had this problem before??
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what resin are you using?
I’ve used vinylester and had this happen due to the resin… i’ve hear others say this about some epoxies (never had that happen myself).
Otherwise how is your mold surface? Was the area where the tacky tape is released? Is it super gloss or smooth? I’ve had vacuum seal issues sometimes because of the mold surface, mostly when using tooling foam.
The last thing I would think is that the bag could be the issue. WHen the tape heats up it gets more gummy and maybe if your bag is too tight and there aren’t enough pleats, then it can cause a lot of pull on the bag. This might be fine when at RT but when it heats up i’ve had things pull and leak.
my 2¢
Many thanks for your reply!
I am using Araldite LY 556 (epoxy) / Hardener XB 3473 (amine), the curious thing is that this issue only happens sometimes. For all the infusions I am using the same surface, material and resin…
I don´t think that the bag is too tight, I put enough pleats, so I don´t think that is an issue…
The set up is done on a smooth heating plate.
The part from the heating plate where the sample goes is previously coated with a release agent (the inside of the first vacuum bag frame), but being careful that the tacky tape never touches that part. As I am using a 2 vacuum bag system, the release agent cannot be the problem, since the failure is always on the outer bag.
interesting… Do you double bag the parts? that may help with some insurance at the very least.
I remember reading some where about some one who had a similar issue. I believe they were using epoxy. I do know that some epoxies are a bit more nasty than others, so I could see how the resin would be suspect. you could maybe try building a wider area of sealant tape around the trouble area? Or using some pieces of rubber as a resin damn maybe?
that sounds like a bit of a tricky one to solve but I think there is a way around this issue.