I had a project recently that provided a good opportunity to try something I’ve had in mind for a while. Building the reinforcements for composite tube connections using VARTM. I’ve used resin transfer with molds any number of times, but I wanted to come up with a way to use infusion in custom, one-off situations like the tube connections pictured below. It took only a little trial and error to come up with a very effective combination of materials and operations to allow a predictable method that works in a wide range of connection geometries.
The basic principal is to apply the reinforcements dry with a very light mist of airtac spray adhesive. Fit the feed lines, vacuum lines, flow media, peel ply, etc. appropriately so that I can quickly establish a large resin front that quickly saturates the laminate at the widest area. Apply stretchlon film and sealing tape to create the bag (this part is a bit of a pain). Pull vacuum through a resin trap, leak check and go. These connections were all infused with epoxy resin, which is tricky anyway, but for small surface areas like these (and establishing a large resin front quickly) worked just fine. Clamping the feed line just before full saturation kept excess resin from relaxing the bag.
There were a dozen or so unique connections on this project that were all infused this way. The results were excellent. No dry areas, pinholes or other problems. Takes a good deal of time and eats up plenty of consumable materials, but other than pregeg, I couldn’t think of a better way to pull this off.