Over the last couple of months, I’ve been struggling to do a proper vacuum infusion of a glass-fiber epoxy plate. After more than 15 attempts, I’m now out of ideas how to solve the dry-spots problem I’m having.
I want to make a glass fiber plate with a stacking sequence [0,0,45,90-45]2s with dimensions 400x300mm. The epoxy I want/have to use is Epikote RIMR 135 - 137.
As a bottom mold I’m using a glass plate (500x500mm) with marbocote 227 release agent on it.
Starting from the glass plate, I add the layers of glass fiber, then a layer of perforated release foil, a layer of distribution mesh (green) and finally the vacuum bag. I also tried using peel ply instead of release foil but the dry spots remain. I use spiral tubing wrapped in breather cloth as inlet and outlet for the epoxy.
I degass the epoxy after mixing it (with the correct ratio) and evacuate the entire mold to full vacuum (in my case -100kPa). I do not have any air leaks, even after 24h of waiting.
Finally, the mold is put on a heater plate, heating the mold up to 40°C. The epoxy reservoir is heated as well to approx. 40°C but not higher.
I then start the infusion which takes about 15 minutes when heating mold and resin, or around 2h when just doing it at room temp. I’ve tried two approaches:
- Having the inlet spiral tube lay on top of the distribution mesh: in this case there is no real flow-front during the infusion but the glass fiber just starts to get wet at different locations underneath the distribution mesh. The pools grow larger as the infusion goes on, but some locations are not as wet as others (they are wetted a little bit, judging by the discoloring). These locations will form the dry spots in the end part.
- No direct connection between inlet tube and distribution mesh: I can then more clearly determine a flow front, but it is not an even front. The epoxy seems to flow around some random points in the plate, leaving them dryer than the other parts. These will then again form the dry spots in the final plate.
I do not have the problem when doing small plates or just doing UD stacking.
Although I’ve checked dozens of Youtube clips, I’m wondering if you guys see anything I might be doing wrong?
Personally, I’m starting to believe that the UD glass fiber mats we have, are not suited for vacuum infusion, but is that possible? I’ve tried to rolls of different glass fiber we have here. The first one was bought long before I started working here, and someone told me it was Roviglas R17/475. The second one is [this one](http://shop1.r-g.de/4DCGI/ezshop?action=direktanzeige&artikelnummer=190157&fromaction=showpage&ButtonName=Fiber reinforcements&Beschriftung=&WorldNr=1&suchbegriff_1=Fiber%20reinforcements&suchbegriff_2=&suchbegriff_3=&suchbegriff_4=&suchbegriff_5=&suchbegriff_6=&suchbegriff_7=&sKontaktID=2182826&sKontaktKEY=0EBUeY2yi4NsrxUYDs4qj2JUzEcvOg&sTICKCOUNT=36262657). Could it be, that it’s the type of fiber that’s causing all the problems?