Does anyone infuse parts with the vac centered on the part and a resin feed channel around the entire perimeter of the part, to create a converging resin flow front (as in LRTM) but with bagging material instead of a B side mold? If not, why?
I your part can withstand something going on in its middle without showing any extra compression and look right once popped out of the mold and viewed in the sun…it works.
It uses a lot more tubing and wasted resin however. ALso…if your lay-up schedule varies due to design, it may not feed exactly even and chance drawing resin into your vac signal before fully infusing.
Thats too many drawbacks for me personally.
Infusion speed is spectacularly faster. That can be a driving factor. Another factor can be the geometry of the part. You want to infuse from the bottom upwards.
The fun thing is that the vacuum port does not need to be spot on. Even when offset, the air will evacuate before the resin does. Fun to watch. Of course a bit of resin will enter the vacuum port, so use a port that can be thrown or cleaned. Also possible is a stretch of MTI hose, if you connect that to a normal hose, you can route that out of the bag through a pleat. No need for a hole in the middle of the bag. (I must admit that in larger projects you can not avoid a couple of vents (or a couple of hundred) in the bag.
Herman, when I run a vac line across the middle of my roofs, it left a compression highlight on the viewable side of my parts. While it was void free, it was still a flaw that would not disappear with wet-sanding or clear-coating.It was a darker area created by the line and compression. Even though it was resting on a bed of bleeder and peelply.
Now I cross infuse.(one side to the other) on the flange with consumables.
A big benefit of a perimeter vacuum is that if you have a leak where the bag attaches to the flange the air is drawn immediately into the vacuum line instead of through your part making a perimeter vacuum slower but safer.
In order to eliminate the vacuum line making an impression in the part you can use peel ply / flow media to raise it off the surface of the part or try using something like Enka Channel
Interesting. Your outcome was very different than mine. I found it to infuse too quickly and even though I made a raised vac signal on a bed, it still managed to make an imprint shadow.
I’m using a lab sized Leybold Trivas D16A and a gravity feed resin pot.( feeds through the bottom of the pot). 29.9" mercury.
Slow the infusion by using smaller hoses.
Depending on laminate thickness you can get an imprint of anything. I usually work with thicker laminates (boats) where that kind of imprint is not likely.
No perimeter vac. A resin channel around perimeter, vac at center of part.
In my opinion everything put on the laminate will leave some traces… I tried many times with many many layers of peel ply bleeder etc. nothing worked, always a small imprint even though the surface still flat