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Is there any company that welds the valves?

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Is there any company that welds the valves?

Postby GTC » Fri Nov 20, 2020 1:26 am

Hi there,
In the last year I replaced more delaminated valves than in my entire kite career.
I don't understand why after 20 years of kite development the companies still glue the valves to the bladder. Is it so difficult to weld the f*cking valves?

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Re: Is there any company that welds the valves?

Postby longwhitecloud » Fri Nov 20, 2020 1:37 am

the companies/ factories changed the ways they applied them

you have 20+ year old kites with no signs of the valves peeling off at all and now 2 year old kites especially in hot countries where the valves are all peeling off.

Massive f###up!

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Re: Is there any company that welds the valves?

Postby Matteo V » Fri Nov 20, 2020 2:08 am

IMHO, glue quality is the main variable, with proper prep and application being just as essential.

Similar to cars, companies just need to make the product last past the warranty period. After that, the sooner the failure, the sooner they will have another sale.

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Re: Is there any company that welds the valves?

Postby PrfctChaos » Fri Nov 20, 2020 4:18 am

I was under the impression that most kite valves in the last 7 years or so were all Ultrasonically welded. Is that not the case, or only the case with the major brands, or has it changed again in the last 2 years?

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Re: Is there any company that welds the valves?

Postby Ventum » Fri Nov 20, 2020 1:36 pm

Most factories (hence brands) use high frequency welding to glue the PVC valves to the PU bladders via a glue foil in between for the adhesion of PVC to PU.

What makes things complicated now a day's is that many inflates are used as deflate in a rotating movement, hence, they require velcro on the inside of the LE and on the bladder. Here different factories use different methods to get this whole package together.

The whole things is quite critical: Power of the machine, quality of the glue foil (believe it or not...there are not so many good ones), time of heatload and pressure of the welding die.
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Re: Is there any company that welds the valves?

Postby knotwindy » Fri Nov 20, 2020 3:53 pm

Are you saying they are doing it fast and cheap instead of right because it is such a small market? Or is it just the ‘nature of the beast’ that they can’t figure it out with too many variables?

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Re: Is there any company that welds the valves?

Postby Mike101 » Fri Nov 20, 2020 5:18 pm

I'm in a similar position, wishing I'd just sold em "slightly leaky" and got rid. Feels wrong though- I'll sell when I've fixed all the leaks, rebridled it and coated it in shoe glue. Then it will be like a new kite again and I can recoup the money of the glue and bits :s

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Re: Is there any company that welds the valves?

Postby Ventum » Fri Nov 20, 2020 10:09 pm

knotwindy wrote:
Fri Nov 20, 2020 3:53 pm
Are you saying they are doing it fast and cheap instead of right because it is such a small market? Or is it just the ‘nature of the beast’ that they can’t figure it out with too many variables?
Just explaining the method used by most factories. Nothing fast and cheap on this method btw, I ran a kite factory and its not so simple as people may think. Something may look perfectly welded in the factory but may contain a weakspot that only starts to leak after some use. No kite leaves a factory without a pressure test. The PU bladder is very thin, the PVC valve (relatively) thick, we now added extra layers because of the twisting inflate/deflate... too much heat and the thin bladder melts too much, not enough and the PVC and glue foil did not heat enough. So yes it is a very complex part and can go wrong because of many factors.

But to be honest.....to my knowledge old kites also delaminated.

When something goes wrong you may see that in an entire batch of brands a+b+c the valves delaminate as they are made in the same factory by the same machines same valves and same foil batch etc.

As for the question in the starting post. You cant weld pvc to PU directkly and I even doubt you can welt a thin PU foil directly to a thick PU valve. The heat from the top part has to transfer through a thicker surface then on the bottom....its not that simple but for sure if the industry was 100 times larger .... Also QC and QA of all different parts and machines cant be the same level as in the airplane industry or the kite would have to cost the 10 fold.


Cheers, Seb.
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Re: Is there any company that welds the valves?

Postby Dave_5280 » Fri Nov 20, 2020 10:49 pm

I think car tires used to have tubes and now the ones I’ve seen are tubeless. Could LEI kites go tubeless? One advantage to foil kites over LEIs.

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Re: Is there any company that welds the valves?

Postby Herman » Sat Nov 21, 2020 8:06 am

Can these glue foiled "welded" joints be peeled back by softening in ~ boiling water in the traditional way??


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