Hello fellow composite technicians and gurus!
I am trying to get some test panels using a light RTM set-up with an injection machine and vacuum. We are just trying to produce a void-free test coupon for our initial tests. We are using 6 plies of 0/90 e-glass and I forget which resin system we are using (we are testing out a variety of them) but they are all designed for resin injection.
I have the two halves sealed with an outer and inner seal. There is a vacuum being pulled on the outer perimeter that is achieving close to 30 in/hg (which is vacuum drop checked) and the vacuum pressure for the cavity is set to about 15 inches or so, also vacuum drop checked.
The resin injection machine we are using, an MVP patriot, is a two chambered unit that catalyzes the resin right at the gun head just before injection. Subsequently we are unable to de-gas which is disheartening, as before we had the injection machine we would degas thoroughly. We are running our injection pressure pretty low, at around 10 psi. We are injecting until the panel is just about completely filled and then we shut it off.
Anyways, I am still finding a fair amount of micro bubbles in the finish so I wanted to reach out and see if there was any input regarding our cavity vacuum pressure or anything like that. Also if it should be increased or reduced at any part of the operation, we have been leaving it at 15 through the injection and cure. Should we consider injecting a bit more so that the earlier, perhaps aerated resin is collected in our catch pot?
Any help is of course appreciated. I have been watching as many tutorials and researching as best I can but I am still having some issues. Let me know if there is any other information that would be useful and I will see what I can determine.
Thank you!!