welding wires together

[coppercone2]

Whats the deal with welding wires?

I watched a indian youtube video, and this dude went even cheaper then usual by refusing to use solder, instead welding wires together with a carbon stick connected to a battery.

Is this practice ever done or defined at all by some kind of standards etc?

I only ever saw it done 'officially' with thermite for ground bonding and high explosives for arial bonding, but never really heard about resistivity wire welding. I know resistance soldering is well defined, but not just making a splice by literally melting two wires into each other. For copper or aluminum wires, nothing fancy like screens in vacuum tubes ETC. Like as a general production method.

I also know you can do it to thermocouples with spot welding. But I mean melting signal/power wires together, nothing exotic, just not to use solder or for some other reason.

[Electro Detective]

Sounds like a mini arc weld, old school carbon arc style, with the battery voltage acting as arc source and current limit

Got a link to that video?

[coppercone2]

he starts doing it 4 minutes in, after he builds the machine with the minimum number of solder joints required before it can finish building itself without solder joints

[Neomys Sapiens]

I see it increasingly in commercial applications. Sometimes I wonder whether the material pairings are really given the necessary thought. Some connections can be made that should be very sensitive to corrosion afterwards, like anything involving copper and steel. Also, industrial users could employ inert gas flushing, which clearly expands the possibilities. This is where spot welding and TIG become a bit muddled sometimes. Where I see it rather often is in grounding connections, where a tab or just a ferrule crimped to a wire is welded onto a piece of sheet metal. also, some test lead connections seem to be made that way - Stäubli(MC) seem to do that extensively. When I needed to solder some 2mm test leads in place I wanted to salvage the stackable gold-plated plugs. I got the two tabs which retain the little flap holding the contact in the plastic body pried open without damage only to discover that the very fine stranded lead is spot welded to the contact and thereby inseperable! In their catalogues, they offer only connectors for soldering, but that explains the quality of their ready-made test leads. The two materials (fine stranded copper and gold plated brass) are fused into one and the wire does not have to suffer from wicking effects. There is not even a hole - the wire is flush against the side of the tiny contact.

Another technology that is used increasingly in electronics context is ultrasonic friction welding.

There are even applications of gas welding to electrical connections. Visit the website of the Spirig company of Switzerland, where they show their oxygen/hydrogen microflame units for brazing and copper welding in both automated and manual applications.
https://www.spirig.com/index.php?id=53&L=788
I have thought repeatedly about aquiring such a system from them, as it would have countless uses in repairing things as well as in building custom adaptors and RF fixtures.

Finally, electron beam welding and laser welding do lend themselves well to precision interconnection work. I have seen a manual laser welding machine in action which is used regularely to produce complex assemblies of small Inconel and other tubing, most of it very thin. The operator did a repair weld for me on a small piece of very thin and fragile material without any effort or preparation.

[eKretz]

This can be done pretty readily with a TIG machine too if you have one with a pulser. Pre-flow the argon for a second and then a good high-current very short duration pulse and bob's yer uncle. Repeat the pulse once a second or so if you need a longer weld and travel as far as needed. You don't want to pulse too frequently or the material will get too hot and melt through or vaporize.

[coppercone2]

I wonder how it stands up to vibration ETC.

What made me think about it is telecom, but they developed those no strip easy crimp gel filled connectors that are even easier, but if you need to do a splice, it would kind of be hard to beat a small battery and a carbon rod vs a soldering iron, solder, flux, etc.

But it would need to be good. But I think those IDC's make it irrelevant. Maybe useful to a developing nation?

But, a good weld, should be really corrosion resistant if its copper on copper on untinned wire I think, because there is no galvanic problems?

But I suspect there is a brittle 'heat affected zone" formed.

however, with copper, especially with stranded wire, it might just get soft since it cools rapidly.. so it might work well?

[eKretz]

Copper is annealed by heating. Doesn't matter how fast or slow it cools.

[coppercone2]

are you sure? when i worked with shitty scavenge I heated the sheets red hot and dunked them in a bucket of water so they could be rolled out with a bakers pin

ok, it says it gets rid of oxide but it does not get it softer. I just did it without thinking about why, thought it was some universal metal law. does it work better on some alloy mixture maybe? I thought it was easier to roll out then without a water dunk.

[eKretz]

Nah, just that it means you can cool it faster and get back to working it without burning yourself. Just about everyone I know dunks it too - including myself. Convenience more than anything.

[coppercone2]

do any metals need a quench to soften? I thought non ferrous metals were the opposite, so if you heat and quench them, they get soft. I think you can harden aluminum by slowly cooling it

[eKretz]

None that I know of. Many metals are heat just above critical temp and then slow cool at a controlled rate. Some are just heat and then air cool. The remaining are heat and then cool as fast or as slow as you like. Certain tool steels will do the opposite and harden if you heat to critical temp and then air cool (A2, etc.).

[Neomys Sapiens]

Another company with applicable products:
https://www.mig-o-mat.com/

[Fred Basset]

Ultrasonic welding of gold wires is used to connect the dies to the pins in ICs.

At first I thought you were referring to so much from China now talking of "welding" parts, when they mean "soldering".  I am not sure why that is happening either?

The only welded things I have come across is where they are spot welding ferrous metals where they will be exposed to high temperatures, like soldering irons, high-temp thermocouples and so on.  I had not seen this before and I suspect it is just about cost?  Although inadvertently they might be helping their environment by reducing the amount of lead used?

[coppercone2]

I am curious if its related to reliability or cost. Usually though I find heating elements break way before the crimps used to attach them break. Most manufacturers sell crimps rated for high temperature and this temperature can be kept in check by reasonable thermal design. The crimps are good to 250C or so. But I believe they are usually steel, and this can rust, and a weld should be more immune to rust then a crimp. But they might be stainless, I never looked into them too much.

I dislike steel contacts, I just threw away a working fan because the freaking switch was rusted internally and it was made of steel, and I don't feel comfortable restoring a shitty desk fan.

[Fred Basset]

A steel switch?  Ugh!  I thought that no matter how much the price was, they would never resort to steel switches again.  Too likely to get a scratch, high point or a touch of rust on them.  Next thing you know, they have welded themselves together in the "On" position.  Too dangerous, even not counting the risk of fire then.  If they have a steel switch, who knows what other corners have been cut?  I think your decision to throw it out was sagely.

Hmm...Never considered crimps.  If you made your own, it would be more machining costs.  Buying them would also increase costs.  So would buying a spot welder, unless you could amortize it over many units, or had one on hand already.  So yes, spot welds could be down to price, as I would imagine they could be done a little quicker also?
 

[eKretz]

Here's a vid by a guy who seems to know what he's doing about those "cold-weld" Chinese machines. Looks like just plain pulsed DC TIG near as I can tell. One difference is that some TIG machines can't be set for zero background amperage. That can be gotten around by just letting go of the pedal and retriggering for every pulse though. Thought some might be interested.

https://youtu.be/V7-mcjR59a4

[coppercone2]

https://youtube.com/shorts/tCN2UI8r8sw?feature=share

Is this ultrasonic or thermal or a mixture?

Nmv, I translated it, its ultrasonic, but I thought it might have been the buzzing of a heater of some kind (resistance transformer). I guess thats standard then.

[geggi1]

Welding is common for subsea MV/HV cables over a certain length. The manufacurer of subsea cables do often assemble the cable of parts manufactured by other companies due to the length  and also the size of the reel there are limitations of the maximum lenght that is possible to have in the assembly machine. The maximum length is decided by the size of the machine and also the cross section of the conductor.
When one reel is finished the conductors ar TIG welded together and the layers of insulation and semiconductors are re-build so that the cable at the joint have the same dimensions as the rest of the cable.
In my experience there would be maximum 2000 m between each joint.
This kind of joint is called an factory-joint in the cable manufacturing business.

[totalnoob]

I used to work at a copper wire factory back in the early 90's.  We made electrical wire and cables everything from 22 ga. to 1000 MCM.  I did not work on the machines that made the smaller, solid and stranded, wires, but I saw it done where the wires were resistance welded with some kind of a thick flux "washer" applied over the joint before the welding took place, then broken off after the weld was completed and before restarting the machine to send the wire through the extruders to add on the two layers of insulation.  I worked on the larger machine that made stranded wires from 8 ga to 1000 MCM and wires that large had to be spliced and then the splice was cut out when it reached the portion of the machine that placed them on the reels. I assume that a welder to weld wires that thick were either not available or were too expensive to be economically feasible for the company I worked for.

[Gregg]

In many places where reliable long term ground connections are needed it is common to use thermite welding to weld the copper ground cable to ground rods, building structure and to connect copper cables together.

[coppercone2]

oh right, totally forgot about that because I was focused on inside of small chassis.

Thermite copper cadweld charges and also high explosive shockwave welding. You could probobly make small tabletop versions of both processes but the one using explosives is illegal without the correct licenses (maybe in new mexico tech).


I will try to find the video of the explosive welding, I saw one before where they were doing powerline splices with it near transmission lines.



Ahh, its called implosion welding. I guess politispeak, or perhaps technical correctness

I have seen some interesting devices made with legal blank ammunition that use explosively driven crimps, but it will not be anywhere close to actual explosives. Why do I think that the impulse drive (gun) crimp will have a different metallurgical properties then a slow pressure one?... i wonder if for better or worse. Could be a interesting use for a old nail gun.

[geggi1]

I have seen the kind of explosive joints used for FeAl powerlines.
They are made up of DETCORD with a internal crimp made of a hard metal.
Its about 25yers ago when I worked at a distribution company as an HV apprentice.