Welders.

[caterpillar guy]

So as to not mix up the other thread on welders. I weld some things with a continuous weld meaning I just change rods and go back to burning rod. I usually weld with higher amps than most will use like seldom below 145 on AC and seldom under 80amps on DC with my portable welder. I have tried to weld with less and all I ever get is sticking with the rod whether it be 7014,7018 or even 6011 or 6013 just doesn't burn well i Also don't bother with rod smaller than 1/8 inch for anything. I have found smaller rod will not fill fast enough and still burns through just as bad with thinner rod on less amperage. I also don't weld on much under an 1/8 inch thick and more in the heavier weights. I don't build much with less than 1/4 inch for strength purposes and the jobs need more iron. I also tend to over build things thickness wise.IT also doesn't break when I'm done either. I have had aluminum welding cables burn off from the ground clamp or the stinger holding them with an extra rag they were so hot. My portable never gets hot like that when welding. When I welded in the new cross members I would just go from one to the other with no stopping unless I had to move to reach them. I think it has a continuous output on it though. Would have to look for the duty cycle on the old AC buzz box. Welding rails up on the Cat tracks and roller we would just start welding and stop to change rods and rollers as we welded many passes around the rollers and idlers. Yes some jobs only take a rod or 2 to do them and it doesn't run long before stopping.

 

[moresmoke]

Its all about having the right tool for the job. I have a little miller multi matic that sits on the corner of my welding table. Its not high power and has a limited duty cycle, however, it will TIG, MIG, and stick and is great for little jobs. I also have a nice portable. The beauty of most portables is 100 percent duty cycle and better bead control.

 

[farmersamm]

Don't mean to be disrespectful.............but what exactly are you asking. I can't really figure it out by reading your post.

If you're asking about duty cycle, then the transformer machine, depending on what it is, probably has a shorter duty cycle than the engine drive.

Never heard of using aluminum leads. Maybe it's just me, but I've actually never heard of it. Aluminum isn't good when it heats up. Tends to loosen the connections as it expands/contracts.

Plus........you need larger diameter aluminum wire to carry the current as a typical copper wire of smaller diameter.

 

[Hemmjo]

Not sure what you are asking either. I am going to take a shot at why your cables are heating up and burning the ends off.

Relative to copper, aluminum is a poor conductor. They do make "copper clad" aluminum welding cables. BUT since aluminum does not conduct as well as copper the alum cable HAVE to to be larger to carry the same current.

Here is what I believe your issue is. The laws of physics are set in stone so to speak, no one can change them. When current flows, heat is generated. As resistance goes up, heat rises. That is why welding works. Resistance between the rod and the work makes enough heat to melt the rod and the base metal.

There is also resistance in the cables AND at the connections on the cable ends. Where ever there is resistance heat is generated. The highest resistance, other than the weld itself is the connections in the cables. As heat rises in a connections, the resistance also rises, generating more heat, raising the resistance, generating more heat... see where this is going. Aluminum expands as it heats. Aluminum "creeps" as it heats, meaning that it can be "extruded" out of the connection as it heats. THEN as it cools, it shrinks, but does not go back to the same size so now it is loose in the connection. Next time you weld, there is even MORE resistance in the connections and back to that more heat, more resistance, more expansion, more extrusion loop again. This happens slowly, your cables may work fine for a while, but as time goes on, things get worse. In addition, the heat also causes the aluminum wire to oxidize, which creates MORE resistance in the connections. If you are making these connections yourself, you should be using "Noalox Anti-Oxidant Compound". Better yet, switch to copper cables

As you stated, your welding is much more intense than most. I weld a bit, reposition, weld some more, add another part, weld some more. During those breaks everything is cooling down.

The welding you describe does not give time for the connections to cool between welding passes. They just keep getting hotter until they fail.

End physics lesson for today..

Good Luck

PS, just FYI; The Aluminum wiring installed in homes in the USA from 1965 to the mid 1970's is responsible for burning down a lot of homes from this same issue.

[b:11a0d36b7d]
https://www.denvergov.org/files/ass...ment/documents/aluminum-electrical-wiring.pdf[/b:11a0d36b7d]