As for the leak test; I make sure that there is absolutely no leak. I have noticed that even the smallest leak can lead to large voids (I’ve already blown a test by thinking that the leak was ‘small enough’). As my test set-up is reasonably simple I can easily check for leaks.
Where I learned vacuum infusion; the area I am specialising in for my studies (Aerospace Engineering) is the design and production of composite parts. Vacuum infusion is a promising production method but cannot be used at present for commericial aviation because the quality of the components that are produced fluctuates too much. This necessitates a lot of testing, which is needless to say an expensive and time consuming process. Basically I am investigating for my final thesis whether it is possible to better control the process thereby making it possible to ‘predict’ (and thus ‘guarantee’) a certain quality level of the part.
My longest resin flow from resin inlet to the vacuum outlet (I presume this is what you’re asking) is about 80 cm. But because I use a runner across the entire mold, the longest flow of the resin through the laminate (perpendicular to the runner) is about 20 cm. You presumed correctly that I don’t use a flow medium throughout the entire laminate (neither on top nor in the laminate). I have put it on my list of experiments.
The vacuum I infuse with is 100 mbar (90% vacuum) and my laminate is only carbon (I only use a strip of surface medium below the metal spiral runner). I’m going to check out the continuous strand fabric, sounds like a possibility. I use a leak detector to check for leaks (doesn’t always work but if I size the vacuum foil right, not too many folds, then it usually does). I also use a digital vacuum pressure meter to measure what the vacuum pressure does (i connect the mold directly to the pump so that the resin trap doesn’t act as a buffer).
I haven’t figure out the cps of my epoxy resin. As you say it also depends on the temp, I don’t wait to long before injection because the exothermic reaction of the resin may cause overheating. It’s a bit of a balance I guess. I don’t have an infrared temp gun to measure temps and a problem I have is controlling the temp. I don’t really have a method of keeping the temp constant (i’m using electric blankets to heat my mold up to 37 deg C but this is a quite unprofesional).
As for the resin, it is a common epoxy resin (i believe it is also used for the vacuum infusion of yachts) but I don’t know whether it’s Russian. I’ll find out later.
So to sum it all up, I think 'm going to mess about with the temp, the mould release agent, the flow media, and the vacuum pressure.
Any other ideas? In any case, thanks for all the tips.
