Membrane Tube Infusion (MTI) hose was introduced in Europe in 2011 by developer and patent-holder, DD-Compound. It is being sold in the U.S. by German Advanced Composites. It’s a vacuum line that can be used in place of spiralwrap, and because it is covered with a semipermeable membrane — Example: Goretex, i.e. fabric can breathe but keeps liquids out —it lets air move through into the evacuation line but not resin. Jay Carpenter, one of the instructors for Abaris’ courses on Resin Infusion, has “road tested” the material to see how it actually performs.
“I was very pleased,” says Carpenter. “When you use other styles of break zones (e.g. peel ply wrapped vac line) they will eventually wet out and you will start drawing resin out of the laminate. The MTI Hose flat out does not draw resin; thus, vacuum is maintained and the resin flow stops.” He adds that with a long, slow-curing resin system, there could be concern about bleeding the laminate out. “With the MTI Hose, that won’t happen.”
What about being able to eliminate a resin catch pot? Carpenter responds, “I can see that as a likely event. However, some will prefer to keep the catch pot, even if it’s just a back-up, because the value of the vacuum pump is so high.”
With regards to using MTI Hose to eliminate the need for calculating optimized resin inlets, Carpenter explains, “with complex or large infusions you may still need multiple inlets. The driver will still be the overall flow distance that the resin can attain in your particular infusion setup.” However, he does see potential in using the MTI Hose to run just one continuous perimeter evac. line.“If resin will arrive at one section of the layout early, and you are using a peel ply-wrapped line, you would normally want to segment the layout and clamp that section off after the break zone starts to wet out. With using the MTI Hose, that isn’t necessary.”
Carpenter was still able to create a trapped dry spot, i.e. “racetrack”. “We were using a core without a good beveled edge and the resin ran quickly around the edges to the end, leaving the center dry.” He explains that is one scenario where in-class experiments have shown value in a semi-permeable membrane across the entire surface, because the material can then breathe vertically across the part versus just at the edges. Schildgen notes that MTI Hose can also be placed on top of the laminate to address such areas, but you need to know where they are.
Carpenter says it is easy to use the MTI Hose, but points out it’s important to remember to seal off the open end of the tube, which is highlighted in the product’s instruction manual and user video. The one end is obviously connected to the vacuum pump, but the other open end must be sealed also.” Carpenter suggests wrapping it a couple of times with sealant tape about ½ inch from the edge. Schildgen says the method in the video is simple and reliable.
“Our first class using the material was really impressed,” says Carpenter. “All of the students asked for the company’s contact information and had ideas for how they wanted to use it.”