Hello, I have a very challenging w

[natllc]

Hello,
I have a very challenging welding problem and need help. Following are the issues and parameters.
We have a device that has two small chambers, each of which contains pressurized (15 psi)very low viscosity fluid (solvent).

The concept includes the mixing of two liquids to form a highly detectible gas to indicate when electrical equipment has overheated. The device is completely mechanical, very small 2"dia.x3"), and we have chosen to use a foil sealed opening that can be pierced by a spring charged plunger.

It is imperative that the liquids in the two containers do not leak as they are highly detectible by the gas sensor. The problem we are having is how to make the foil sealed opening. Welding is the only method we consider reliable for sealing so we need to design a foil orifice that, perhaps consists of two washers with the foil sandwiched between and welded at the edges. That is the path we are pursuing but I am certainly open to any ideas or referrals.
Thanks

Bruce, Nichols Technology

 

[metman]

electron beam welding might be a solution.

Design for RELIABILITY, manufacturability, and maintainability

 

[dgallup]

Are the solvents in the device when you want to weld it or is the device empty? I can't see welding when it's full. The heat is going to cause the solvent to evaporate & probably ignite. If it's empty then that's not a concern. Laser welding is usually cheaper and faster then EB welding for mass production as there is no need to draw a vacuum for laser welding.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[btrueblood]

I've seen very thin diaphragms welded automatically with a micro Tig torch, pulsed power supply, and fixturing the parts to turn on a small lathe. We could not see the weld seam on the parts even with 60x magnification.

 

[natllc]

Metman, dgallup; Thanks to you both and you are both correcto. I have discovered an old patent that shows how to manufacture a foil sealed opening using.....wait for it.....EB welding. Thanks, you were both on the right track. Thanks for your help and excellent responses.

Bruce, Nichols Technology

 

[metman]

natllc,
Don't jump to quick to EB. It is a relatively expensive process. You should consider btrueblood's suggestion or maybe the lazer weld.

Design for RELIABILITY, manufacturability, and maintainability

 

[natllc]

Don't worry, I've been doing this 30 years so I've picked up a few things. I knew what I wanted but didn't want to spend the money to develop and establish parameters. I'm well versed in all aspects of joining but not welding .0005 foil to substrate. My first assumption was that it had to be sandwiched between two weldable washers and that is generally how they did it, fusing through the cross section, and foil, to seal the opening. Cost isn't an issue as our device is a sensor for monitoring high voltage transformers for overheating. So, if it works, cost will not be an issue.


Bruce, Nichols Technology

 

[Ron]

Since pressures are low, why not consider an adhesive or epoxy adhesive to mount the foil. Hot melt adhesive might be another option.

 

[natllc]

The inside of large substation transformers is an environment of great liability. Nothing goes in that can stay there for 30 years or longer. The only joining methods used in these areas are silver brazing and welding, and that's the reason for having to weld the foil. Thanks

Bruce, Nichols Technology

 

[Guest102023]

Plasma arc welding should also be considered whenever GTAW is proposed for a critical application.

 

[cloa]

http://ir.library.osaka-u.ac.jp/dspace/bitstream/11094/9012/1/jwri34_01_019.pdf

 

[mighoser]

We EB weld 50 micron CP Ti foils. The foil is sandwiched between two washers and welded while rotating. Oxidation of the foil is one reason to EB weld but proper shielding and laser or micro TIG could work. One tip is that you have to tack the foil in place so that it stretches evenly when you do the full seal weld.