7018AC isn't for AC machines???

[Arc weld]

Here's one that would make a great episode on mythbusters! The sales manager where I work is always trying to show how knowledgeable he is, well in his own mind anyway. Half the time I have to give my head a shake. Today was one of those days. He was saying that Lincoln 7018AC is not for AC machines. He said the AC stands for arc control and it does not make welding with an AC machine any easier than standard 7018. I have used it on AC machines and noticed it is easier to use as have a lot of other people. I said 7018 has always been an an AC/DC reverse electrode. He agreed, which contradicted his previous statement, but then he said 7014 is just as strong. Then I said 7014 is for static loading and 7018 is for dynamic loading. He agreed again but said the ONLY difference is 7018 has 29% elongation and 7014 is only about 22% elongation. What's rather strange then is why Lincoln makes 7018AC in the first place since it has lower mechanical properties and higher moisture absorption rates compared to their standard 7018 yet costs more.:confused2: What's even stranger is why would Lincoln describe it as being specifically made to use on lower open circuit voltage AC welding machines? One of the outside salesmen says we need to have a machine like an ear plug vender where you turn a knob and it dispenses ear plugs but instead of ear plugs, it dispenses Prozac. Now that I can agree with!:cool2:

From the Lincoln brochure:

KEY FEATURES
AC polarity welding
Low open circuit voltage operation
Minimal spatter
Capable of cold re-strikes
Conformances
AWS E7018 H8 Mild Steel, Low Hydrogen

 

[bandaidmd]

"What's rather strange then is why Lincoln makes 7018AC in the first place since it has lower mechanical properties and higher moisture absorption rates compared to their standard 7018 . "
They are both 70.000 psi so what mechanical property is lower.

 

[Arc weld]

Charpy V notch impact values for one. The whole point of my post is that if a more expensive rod didn't work any better on AC, Lincoln wouldn't make it in the first place. Whether the AC stands for arc control or AC current doesn't matter. The fact is that it is much easier to use on a low OCV AC welding machine.

 

[Texasmark]

I have used the AC on AC feed and DC rev. polarity. I prefer the rod on DC rev. and love the rod for farm welding chores I have, regardless of the thickness of the material....usually 1/2" thick or less. As far as what AC represents, I think it is far fetched to think it is a reference to Arc Control. Common sense lends itself to distinguish between the type of power applied.....aka you could use it satisfactorily with a cheap stick that only had the AC capability which is all I could afford initially and was why I used the rod....and still do but on DCR as stated with my current welder.

Mark

 

[CalG]

The rod I purchased the other day is marked 7018-1

Didn't get the maker, I just buy it buy the handful (weight) from bulk.

Looking it up just now it appears to be a Lincoln product and is suitable for AC and all positions but Down.

I had a devil of a time with a couple of sticks. Hard to start, then the arc would just extinguish right in the middle of the pass. Almost like the flux froze up between the arc.

Hard to get started again too.

Most of the other rod started and burned just fine.

A was using "junk steel", cleaned up with a cup wheel, 1/8th inch rod set about 125 -130 amps.

Oh! another question, The welder is just a little Miller Thunderbolt

PRetty much this one
http://www.rme4x4.com/attachment.php?attachmentid=70122&d=1330134916&thumb=1

THere was a big difference starting and running on HIGH range than it was on LOW range, even when the amperages were set the same. (again 125-130)

I will say that 7018-1 makes some very smooth puddles. Good thing that, the flux is as hard as rocks!

Any ideas why that is?

Cheers

Cal

 

[Arc weld]

-1 is very common and just means it has a little better low impact properties than plain 7018. Don't go buy what the machine says for amperage, go buy what the puddle is doing. Try using 7018AC on your Thunderbolt and you should notice a difference. You would be the perfect candidate to see if you could tell a difference between the 7018 you have and 7018AC.

 

[CalG]

Thanks for the suggestion.

I asked for AC, But no......

I'll need to take the 20 mile drive to the "other" weld shop. (Airgas) And see what's on the shelves.

As I related, The rods ran very well and only a couple were bad starters.

That sudden extinction thing was annoying though. Almost like the someone flipped a breaker.

Do you know if the Voltage is different between the ranges on that old T-bolt? Might account for something.

 

[Mark @ Everlast]

If you get to the point the rod suddenly extinguishes, it could mean the welder is getting warm or the duty cycle is being extinguished. I don't think these units had thermal protection and as the units got hotter, the weaker, more unstable the arc as resistance increased in the circuitry...or could be that if it is old, it has been overheated repeatedly and has caused some issues.

 

[Reverser]

CalG,
Not too long ago, someone mentioned that the OCV volts are higher on the low range side as opposed to the high range on the same amp setting. So low range may work better for you with the 7018.

And like Arc Weld said, the 7018AC will probably have better control, although you said the 7018-1 ran well most of the time. You can get the 7018AC most anywhere. I've seen it in little packs at Tractor Supply and also at Ace Hardware.

You also mentioned that you buy handfuls of 7018-1 out of bulk, which sounds like it's out of an opened container. You might try baking the rod in an oven and see if it runs better.

 

[CalG]

Thanks for the comments and tips

Mark,

When I looked inside the case some years back to lubricate the cooling fan (it needs lube again) I didn't see much "circutry" in there. A honkin' transformer and the switch gear is about it. I'm not sure were resistance could come in. Perhaps I should go through and shiney up the connections. Couldn't hurt.

Reverser.

The starting is much better on the low range, high setting, than it is on the alternate. Might be that voltage thing ;-)

I thought about the dryness issue and put the rod above the wood stove over night. I'll see if I can tell the difference today.
In reading, The mention regarding water take up in the low-hi rod did not suggest starting or running issues, but rather weld quality at a level not easily detected by eye.

I always store what little bit of rod I keep around on top of the wall mounted gas heater in the machine room. The pilot runs 24/7 and there is always a rising column of warm air right there.

Should be good enough for the hack work I do.