Try to test it the same way you’ve done your lines in the past -( if its a repeat item). Thats a very good baseline test.
Yes, but make sure that the parameters are correct!
I would like to mention another positive thing about the MTI hose that I do not hear mentioned, and I believe its because most people do not practice or observe this; With MTI hose, you can connect your vacuum source (MTI hose) directly to your laminate (High permeability), unlike a ~50mm peel ply break zone, which has a very low permeability. The peel ply break impedes the draw of vacuum at the laminate compared to the vacuum pump (this can take several hours to reach full vacuum). Anyone that infuses should connect a digital absolute pressure gauge to the resin inlet line to observe actual pressure levels in the bag before infusing. Most will only observe this at the pump which is irrelevant. The MTI will decrease the time needed to vacuum soak a part to reach full vacuum level. Regardless(MTI hose, or peel ply break), if youre not monitoring vacuum (pressure) level at the laminate, then you are infusing blind.
Very very interesting observation I would have never thought off … thank you for enlighten us … this infusión thing is full of small but very relevant details …
O yes, indeed there is no need at all for a brake zone. You can toss the MTI on the mesh if needed.
Such a precise digital absolute pressure gauge (barometer) is now available in America through German Advanced Composite`s onlineshop. The reading is the pressure above the absolute zero of pressure (or perfect vacuum). Unlike the unprecise dial gauge usually used to measure the pressure relative to atmospheric pressure (manometer) this device is uneffected by weather or altitude. It responds to pressure changes with a resolution of 1mbar down to absolute zero in an instant which does not only save time with setting up the vacuum system and finding leaks. It is also a reliable performance indicator for the quality of the infusion process because for the first time you know exactly what is happening inside the vacuum bag even in the low pressure range a high-quality infusion process usually takes place.
Another supplier for your Absolute Vac Gauge is Vacmobile NZ, they also have a very good leak detector, see link below,
http://www.vacmobiles.com/shop/absolute-gauge/instruments.html
John Hayes
www.bladerunneroutriggers.com
Vacmobiles is a great company to work with. Excellent service and knowledge.
After playing with MTI hose for a few tries, I really like it; my pieces come out pretty perfect.
Plus, I re-use the spiral from used MTI hose to do infusion set-ups…save a few dollars here too.
Hi guys, for a while i was struggling to pull perfect parts using the traditional spiral but after using MTI i was amazed coz the parts came out perfect and i really mean it “no pin hole, bubbles or dry spots” so in short i will urge ppl to give this a try.
So say I was going to infuse a diffuser, (which I will be) and that diffuser has six fins. Those six fins always come out with tiny air pockets that I have to later on sand and fill with clear resin. It would be safe to put vacuum in each of those fins? Perhaps it would be overkill and I should try infusing normally by just replacing the spiral tubing with the MTI hose and see where that gets me first?
Hi, best will be when you post a picture so that we can help you. I am sure MTI will help, but maybee you should change some other small things like resin flow or vacuum too to get a perfect result.
To defuse critical points it could be a solution to place the MTI hose directly on top of the laminate forcing the resin into these areas. But as Dominik said, a few pictures would help to get a better idea of the issue.
Hey guys , I made a little test with MTI hose - with its membrane exactly - > I turned vacum on normal vacum hose and close it with flat MTI membrane . The result was strange cause Mti membrane didnt suck air, how its possible?!
Its not designed to work without its shell structure-( spiral tube). Your defeating its component marriage. You have basically sucked down against itself and closed off its flow.
I have to ask what you would find? Placing your hand over a vac hose is basically what you’ve replicated.
yhh… It is said MTI is permeable for air and thats why it sucks air from laminate , so i just wonder why it doesn’t let in air when i close one end of hose with mti membrane?
worldwealth - i dont think your hand is permeable for air…
The Membrane is permeable for air. But than smaller the piece/surface of the MTI hose/membrane than less air can pass.
What did you want to do? Just use a few cm of MTI at the end of your vacuum hose? That it will take a lot time to evacuate the air. Therefor the MTI hose was not made. It was made to use it around the perimeter or in some cases across.
I’ve run into this problem for parts with short stretches of MTI hose but in a large bag. In cases such as this, I evacuate the bulk of the air from the resin feed/inlet line, clamp it, and then transfer the vacuum draw line to the vacuum line of the bag. Ends up working out very well.
I actually have my vacuum draw line set up with a quick connector, and then I have a ball port valve attached to a quick connector on one end and a barb on the other end. This way I can quickly check for leaks under full vacuum being drawn from the resin inlet, and easily reposition the bag by disconnecting the vacuum draw line from the quick connect, opening the ball and letting some air back into the bag to repositioning tight corners and such.
That is correct.
The microporousity of the membrane causes a resistance for air and a certain pressure drop along its length. A glance at the MTI hose spec sheet shows that the membrane sleeve has an extraction capacity of 20 liter/min. and meter with Pabs = 50hPa (1.47inHG). One could test that by inflating a ballon and let the air blowing into the MTI hose (closed on one end).