Spot Welder Electrodes Stick Baaad

Got this modded spot welder for a year now.
The welding head has been removed from the body with the transformer and the control panel and an aluminum extension arm was milled to mount it on a table for huge pack depth.
* Wiring and hoses were extended along with 75mm2 cables going from the transformer to the welding head.

Until today it worked for a year perfectly and even changed the electrodes only once a few month ago.

Suddenly, with same nickel, same settings, same electrodes it sticks like crazy on 90% of the welds (welds are strong).

I tried sanding the tips (tried big flat and also pointy), replacing electrodes, changed electrodes angle a bit, same air pressure, lower power (of course) which just weakened the welds but still sticks, lower pulses (using 4), made the head press for a longer delay before firing, different nickels with and without slots (all 0.15mm pure nickel), different cells and NADA!

Something weird that I noticed with the machine that probably isn't related is that on strong electrode pressure and also with the head pressing for longer before firing the welds come out super weak which makes no sense to me.
What always worked for me was the head pressing the lightest the machine can (which is still a pressure you don't want you fingers getting caught in) and the touch is super brief.

Power on my machine is usually 300-350 (don't know what it means in current).
Pulse number is 4
Touch delay is 5

Would appreciate any help greatly!

The sticking is because the metal spot-weld connection is getting soft, most likely from heat. If it is the probe tips, you might consider trying probes that are tungsten or possibly half copper/half tungsten.

If the nickel is actually nickel-plated steel, that would explain why the same settings are getting the nickel-strips hotter. Steel is an IACS of about 5 (IIRC), and pure nickel is around 22 or so (copper conductivity is 100/100 on the IACS scale).

My best bet is the nickel strips are steel at the core.

https://www.bluesea.com/resources/108/Electrical_Conductivity_of_Materials

spinningmagnets said:

The sticking is because the metal spot-weld connection is getting soft, most likely from heat. If it is the probe tips, you might consider trying probes that are tungsten or possibly half copper/half tungsten.

If the nickel is actually nickel-plated steel, that would explain why the same settings are getting the nickel-strips hotter. Steel is an IACS of about 5 (IIRC), and pure nickel is around 22 or so (copper conductivity is 100/100 on the IACS scale).

My best bet is the nickel strips are steel at the core.

https://www.bluesea.com/resources/108/Electrical_Conductivity_of_Materials

Click to expand...

No way, tested it already (I test every roll), plus I mentioned that it happened with every other nickel I tried which all of them (including the one I was initially having problems with) stuck real bad.

Will try to look for a 3mm tungsten rods locally and hopefully be able to shape them with a drill playing as a lathe grinding diagonally on a sanding stone to get it pointy (heard it's the hardest and least scratchable material on the planet...)

I tried tungsten... It was unusable due to... Sticking :? But I know others have used it with good success.
My thoughts would be(in no particular order) :

Loss of power from machine
Corroded connection
Heat affected/contaminated electrodes
Electrodes wider due to shortening

I use solid copper wire for my electrodes (just strip it out of solid core wiring) , it's the same width all the way up, about 30mm of stick out. When the end gets manky and sanding/filing doesn't work, I clip off about 2mm and start again. Usually solves the problem. Looks like you could try it with those heads.
Good luck... Its certainly annoying!

Oh and tungsten is by no means the hardest material on the planet! No where near it. An ordinary grinding wheel will make mince meat of it, so you'll have no issue shaping the end. It is the hardest pure metal, so you won't be able to use any metal based tools with it, files etc. Tungsten carbide on the other hand is extremely hard and tough, usually requires diamond tools to cut/shape.

kdog said:

I tried tungsten... It was unusable due to... Sticking :? But I know others have used it with good success.
My thoughts would be(in no particular order) :

Loss of power from machine
Corroded connection
Heat affected/contaminated electrodes
Electrodes wider due to shortening

I use solid copper wire for my electrodes (just strip it out of solid core wiring) , it's the same width all the way up, about 30mm of stick out. When the end gets manky and sanding/filing doesn't work, I clip off about 2mm and start again. Usually solves the problem. Looks like you could try it with those heads.
Good luck... Its certainly annoying!

Click to expand...

How can Tungsten be sticking? I thought sticking is caused by the copper tip melting while tungsten has a melting point of 3 times more than copper.

As to your ideas for the cause, how can it be loss of power if usually sticking happens when you have too much power?
* I also get many of those bangs and pops that make the spot weld area fly off with sparks (used to happen every few hundred welds and now after every few dozen)

I also tried new and pointy electrodes.

Wrt loss of power: still enough to weld but not enough to free the electrode once the weld is made is my thought. With a good weld, i usually notice a tiny amount of copper on the nickel that has departed the electrode. This is only based on observation of my own set up and might not apply to others.
The tungsten stuck. omg it stuck fast, welded in place. Had to cut it off with an angle grinder. Could have been sort of brazed in situ, but it looked like it had welded. Whatever.... Angle grinder every time, or tear a hole in the can getting it off, and grind the remains off. Brutal! Never did it on a new cell. A friend with more power had great results though. Again I think more power vaporised the metal under the tip and freed the electrode (but didn't blow the weld) Tungsten has lower conductivity and my voltage wasn't high enough to drive the required amps.
Maybe nickel has migrated into your electrode tips making them now unsuitable (speculative, but I don't think impossible)

Something weird that I noticed with the machine that probably isn't related is that on strong electrode pressure and also with the head pressing for longer before firing the welds come out super weak which makes no sense to me.
What always worked for me was the head pressing the lightest the machine can (which is still a pressure you don't want you fingers getting caught in) and the touch is super brief.

Click to expand...

Probly relates to the amount of heat generated by the varying resistance of your contact pre-weld
Less pressure = more R=more heat
And vice versa. Ive found the same too. But too light leads to blow outs which scare the bejeezes out of you :lol:

kdog said:

Something weird that I noticed with the machine that probably isn't related is that on strong electrode pressure and also with the head pressing for longer before firing the welds come out super weak which makes no sense to me.
What always worked for me was the head pressing the lightest the machine can (which is still a pressure you don't want you fingers getting caught in) and the touch is super brief.

Click to expand...

Probly relates to the amount of heat generated by the varying resistance of your contact pre-weld
Less pressure = more R=more heat
And vice versa. Ive found the same too. But too light leads to blow outs which scare the bejeezes out of you :lol:

Click to expand...

So you say try to increase power to avoid sticking?

and again, how can tungsten melt easier than copper? maybe you had some kind of a brazing low temp metal mix?

and yes, those blowouts make me have very girly reflexes I'm glad I work alone :lol:

Obviously tungsten melts at way higher temp but whatever the process was, brazing most likely it stuck hard. Micro arcing could potentially melt the surface but I don't think so. I was so dissapointed cause I thought tungsten would be grand.
If you haven't tried more power then try it. I'm not talking stupid power just a slight increase (careful of those nasty scary blowouts!) it's unlikely to be the issue but maybe.
I just remembered.... I had a period where I'd loose power after about 30mins or so and the welds would get really weak. Turned out that my SSR was in the sun and combined with the work load it was getting really hot. Then for some reason the amount of current (not intentional thermal rollback, more of a passive process I think) flowing reduced and welding went to pot.
Keep us posted if you figure it out :thumb:

Maybe something is up with the transformer...???

GodsWarrior said:

Maybe something is up with the transformer...???

Click to expand...

I thought about it, but what could it be?
It doesn't have any components...

Good point. Maybe wind-
ing or???

GodsWarrior said:

Good point. Maybe wind-
ing or???

Click to expand...

Look at it, it has barely two turns of thick a$$ copper

kdog said:

Obviously tungsten melts at way higher temp but whatever the process was, brazing most likely it stuck hard. Micro arcing could potentially melt the surface but I don't think so. I was so dissapointed cause I thought tungsten would be grand.
If you haven't tried more power then try it. I'm not talking stupid power just a slight increase (careful of those nasty scary blowouts!) it's unlikely to be the issue but maybe.
I just remembered.... I had a period where I'd loose power after about 30mins or so and the welds would get really weak. Turned out that my SSR was in the sun and combined with the work load it was getting really hot. Then for some reason the amount of current (not intentional thermal rollback, more of a passive process I think) flowing reduced and welding went to pot.
Keep us posted if you figure it out :thumb:

Click to expand...

Got some pure tungsten rods today, paid like $60 for the cheap kind as they sell it only in 10 packs, cut it, ground it to pointy but flattened the tips and you are right, I have no idea how people recommend it, maybe for industrial spot welding but not for batteries that use thin nickel strips.
It just blows a hole in the nickel at low current even and welds itself shut to the cell.

no good. I'm thinking maybe something has gone wrong with the switching circuitry, for sure nothing is going to go wrong with those two coils (unless there's s short somewhere) . Very mysterious specially since you changed the electrodes etc.
Start from the plug and check over it again. I'm outta ideas.

Maybe the grid is running outta juice.
You have stable wall voltage? Did you move the machine from one room to another, perhaps with alot of Vdrop in the lineV? Thats a 220v welder?

BTW.. I like your pack clamp. Looks usefull, and very simple and sturdy.

Maybe try Thoriated tungsten. Much much higher melting point.. just a lil ( tiny bit) radioactive.

DogDipstick said:

Maybe the grid is running outta juice.
You have stable wall voltage? Did you move the machine from one room to another, perhaps with alot of Vdrop in the lineV? Thats a 220v welder?

BTW.. I like your pack clamp. Looks usefull, and very simple and sturdy.

Maybe try Thoriated tungsten. Much much higher melting point.. just a lil ( tiny bit) radioactive.

Click to expand...

I don't think it's loss of power, I can get a ton of power to blow a hole in the cell.

It's a 220V grid.

Yeah that clamp is great, cnc'd 15mm plexiglass and M8 thumbscrews.

I won't go with anything called tungsten again, it's just horrible even though I ordered like a week ago a stick of tungsten copper (70/30%) but I hope I wouldn't need it as it seems that the problem just vanished!
I hope it wouldn't go back, moved to a new workshop today and haven't tried it here so maybe things will be different here, we will see...

I wish I could help you with a piece of advice but I'm only at the beginning of my career as an electrician. These pics seem to be quite familiar to me. When I studied in the first semester in college we learned something about this. I chose to be an electrician because of the high salary and because it's an interesting job. You always have to deal with some difficult situations and you should know how to do that. Here is the site (https://www.electricianclasses.com/salary/) where you can find more information about the electrician's job. I hope after graduation from college I will be a professional and then I will help everyone.

If you are blowing holes in nickel ribbon, then the current is way too high. If the settings are the same as when you were getting perfect welds, then I suspect the machine is malfunctioning.

The sudden nature of the change seems to agree that it's current setting is way off.

Side note: in the future, also try carbon gouging rods. They are cheap per rod, but you might have to buy 20 in a bundle to get two of them

This problem was pretty close to me a few weeks ago. The exact same welder was literally pissing me off with its inefficiency. It was causing power surges in the garage, and it wasn't good until I decided to get some extra help.
I think that you will also find it helpful to know about the solution to my issue, namely the help from gordonpowers.com.au. It was new to me when electricians solve such tasks, and they do it very well. Try to take advantage of this opportunity; you won't lose anything, nevertheless.

I agree with spinningmagents. The heat from the weld is causing the sticking/erosion. If you do a crap job profiling your electrodes this will start a chain reaction where the uneven rough parts of the electrode will get hotter, melt, stick and then pull off more of the electrode which makes another rough surface on the electrode and starts the cycle again. This also happens if you profile the tips with a really sharp point. Making a smooth small round tip similar to a BIC crystal pen will give a nice amount of weld area whilst not sticking. If you rotate the area which is in contact with the surface of the material and you hold the electrodes at an angle you very rarely ever need to reprofile the tips because the opposite of the above happens. There are probably also other things that can cause sticking like too much current, surface contamination or material composition but those will be obvious. The majority of this will not really help your situation because the type of electrodes you are using naturally want to mushroom and you cannot change their rotation and angle on each weld to naturally reshape them as they change. Try using something different to a file when you clean them up and check them under a magnifying glass to see if they have any sharp bits or rough bits, anything that is small and doesn't have sufficient material around it to cool it will melt.