Impluse heat sealer for thermal urethane

Discussion in 'Sailboats' started by kach22i, Aug 22, 2007.

  1. kach22i
    Joined: Feb 2005
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    Location: Michigan

    kach22i Architect

    I need to source an Impluse heat sealer for thermal urethane.

    I'm thinking that some of you making your own sails may of experimented with thermal urethanes, at least the ones who don't like to sew. This is for use on a hovercraft skirt, which is thicker than ripstop, but not too disimlar. Us "full of air" guys have to stick together, right?

    I have some samples of heat sealable fabric for making waterproof bags (nylon base 420 denier with a nice thick urethane coating one side 0.30mm). They said you can just iron it with a household iron, but that leaves something to be desired. Problem is both sides should be heat activated at the same time and pressure kept on after the heat is removed and until it cools. An iron can't do that, and an iron has a hard time doing straight lines (mine are two feet long). By the time I get it to seal well, it starts to bubble and ruins the finish. If I go over it several times it ends up stiffing the fabric (bad for my application).

    My first product choice would be the T-Clamp a $3,000 Vertrod Style by Therm-O-Seal, but I can't afford it.
    http://www.therm-o-seal.com/equipment.handsealers.html

    My last choice is $40 from Harbor Freight, might be better off with the iron.
    http://www.harborfreight.com/cpi/cta...emnumber=43477

    The local rental place has nothing to rent me, the local tent and awning place only sews things and is expensive.

    Any suggestions besides Craig's List and E-bay?

    FYI: On the lighter side - perhaps for sails?
    http://www.rockywoods.com/heat_nylon.htm
     
  2. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    The real deal for this application is an RF heat sealing machine. Seals are made by radio frequency waves as the name implies. One is called Thermatron. Another is K-Bar. This is very big dollar equipment as in 5 or 6 figures. Search for a substantial business firm who does tarps, sporting goods, Bank deposit bags, ladies purses, back packs and that sort of thing. You may be able to have them do your work for you. I used to have three such machines in my manufacturing firm. That was before the Asians put me out of business with prices that I could not see with a telescope. I hope there are still some US outfits who still do this kind of thing. There may be someone in your area. It's worth a try.
     
  3. kach22i
    Joined: Feb 2005
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    Location: Michigan

    kach22i Architect

    I did a quick Google search, it does look like there is an industry set up just to RF weld things. I'll do some more looking, thank you for the lead messabout.
     
  4. BWD
    Joined: Aug 2006
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    Location: Virginia, US

    BWD Senior Member

    I do some kitesurfing and so have had to do tpu repair on the kite air bladders.

    Don't know if this technique is as good for fabric/film laminate, but a clothes iron does work for me for repairs to film.
    The key to getting a straight line is backing the area you want to seam with a dowell or cardboard tube (from a clothes hanger). dowel may need a light fabric or parchment coating.

    Better for big seams (or if you sneeze)is to use a board edge so material falls out of way of the iron. But if you are working inside a tube, a cardboard dowell can be slid about where needed and extracted through a tiny incision later...
    I do know the amount of heat needed is "just enough." Learned that :rolleyes:. Sorry if you already tried this method and it was not good.

    Another thing that works really well for tpu is "aquaseal" wetsuit repair glue. This stuff is PU glue that's very strong but flexible when cured. Great for wetsuits, sails, tpu, etc. Flexible and stronger than ripstop or light dacron. Drawback is it costs a lot in the little tubes they sell at scuba/outdoor stores.

    Bet you can get something similar by the gallon though. You might be able to sew your craft's skirts and then encapsulate the seam with this stuff.

    I'd think you need stitching to take some load so the weld or PU glue doesn't delaminate the tpu/fabric and cause leaks or failure. If the fabric is impregnated rather than coated, maybe no stitching needed though?

    That tpu is strong and stretchy but only like being stretched in a uniform way. As a film it will concentrate stress in small areas and fail given the chance. Hopefully being laminated to fabric gets you around this. Good luck!
     

    Attached Files:

  5. kach22i
    Joined: Feb 2005
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    Location: Michigan

    kach22i Architect

    Thank you very much for the fine drawing BWD.:) I'm going to give that method a try, just printed it out.

    I've tried all sorts of glues, none really worked the way I wanted but Aquaseal came closest with out getting into two-part special order stuff. I put samples in the freezer and in the oven, as hovercraft operate in all extreems.

    I went with something that can be ironed to avoid glues. The low temperature in the oven (equal to something black left out in the sun on a hot day 120-150 F), ruined most of my test samples.
     

  6. BWD
    Joined: Aug 2006
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    Location: Virginia, US

    BWD Senior Member

    Best of luck. That method is good for the plain tpu film, hope it translates to your material.
     
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