Cold Weld - Non Toxic?
Cold Weld - Non Toxic?
(OP)
Hello:
I am working on a drinking container where I have to adhere 304 stainless steel tubing to 301 full hard stainless steel shim metal.
I am not able to weld the two materials together so I was looking at cold welding the two items together. However, after the cold weld has set it will be submerged in drinking water for long periods of time so it can not be toxic (or let go).
So far we have been testing different Loctite and JB cold weld brands but both companies are not recommending them for our application as they are not approved for use within such products.
Any suggestions?
Thanks.
I am working on a drinking container where I have to adhere 304 stainless steel tubing to 301 full hard stainless steel shim metal.
I am not able to weld the two materials together so I was looking at cold welding the two items together. However, after the cold weld has set it will be submerged in drinking water for long periods of time so it can not be toxic (or let go).
So far we have been testing different Loctite and JB cold weld brands but both companies are not recommending them for our application as they are not approved for use within such products.
Any suggestions?
Thanks.





RE: Cold Weld - Non Toxic?
Search for the term "NSF approved epoxy". NSF-61 I believe is the standard for potable water systems/devices.
The temperature at which your device is intended (or unintentionally exposed to) will probably also be useful for a manufacturer of adhesives to know.
RE: Cold Weld - Non Toxic?
Do you recommend any particular NSF-61 epoxy products which would provide a strong bond between stainless steel products? The temperatures I'm working with will be average room temperatures.
Thanks.
RE: Cold Weld - Non Toxic?
RE: Cold Weld - Non Toxic?
Mike Halloran
Pembroke Pines, FL, USA
RE: Cold Weld - Non Toxic?
Micro-Tig will probably do the job if not laser welding.
RE: Cold Weld - Non Toxic?
I am not flaring the tube, the bond area is fairly small, half inch wide shim metal bonded to the side of the tube.
With regards to the tickness of the metal, the tube is .25 OD, and the shim metal is 3 thou
Will Micro-tig destroy such thin metal?
RE: Cold Weld - Non Toxic?
RE: Cold Weld - Non Toxic?
No responsible adhesive supplier would recommend that.
Mike Halloran
Pembroke Pines, FL, USA
RE: Cold Weld - Non Toxic?
RE: Cold Weld - Non Toxic?
RE: Cold Weld - Non Toxic?
I was not able to locate any type of spring clip or "locking ring" type of solution that would both work well and look good. The shim metal is great but I need to adhere the two together.
Any ideas would be great.
Thanks.
RE: Cold Weld - Non Toxic?
RE: Cold Weld - Non Toxic?
http://img405.imageshack.us/img405/9883/tubeintube.png
RE: Cold Weld - Non Toxic?
Something closer to a drawing might be more clear.
The issue that's still unresolved is where the shim stock goes. Is its plane of symmetry normal to the axis of the tubes, or does it intersect either, or contain either?
Secondary issue: Do you intend for the tubes to be concentric?
Mike Halloran
Pembroke Pines, FL, USA
RE: Cold Weld - Non Toxic?
http://img404.imageshack.us/i/tubeintube2.png/
This image shows the shim metal in place attached to the inner tube which allows the inner tube to stay in place within the larger tube. I hope this image clears up the idea of the shim metal being used to hold the small tube in place. We've tested it and it works well, however, we don't have a good / safe adhesive to use so we're not sure what to do to hold it in place.
RE: Cold Weld - Non Toxic?
I still don't see a lot of bond area, unless the shim stock is formed around both tubes.
Consider this: Make the shim stock longer and put two gentle bends in it, so it takes the shape of a bulged triangle, which you bulge a little more to push the smaller tube into.
That makes the assembly self-fixturing, and may provide enough friction for retention; that's not clear from what we know so far.
If friction alone is not sufficient, you can (with some tooling cost) spot weld the shim to both tubes, or just put a dab of TIG weld on the accessible ends.
Mike Halloran
Pembroke Pines, FL, USA
RE: Cold Weld - Non Toxic?
Friction seems to be enough to hold the smaller tube with shim in place within the larger tube.
I have not tried bending the shim yet but if it can be done and self-fixturing then it would be great.
We are looking at large production so we need a method where we can construct many units with minimal time and costs.
RE: Cold Weld - Non Toxic?
The self-fixture design regarding bending the metal failed to hold the tube in place as it would twist from its own weight.
I took the metal to a shop and had it both spot welded and TIG welded and both destroyed the metal as it was too thin.
Any other thoughts? Does anyone know of a type of locking ring currently being sold that would work or a type of spring/wire/crimp?
RE: Cold Weld - Non Toxic?