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-   -   Wire feed welder duty cycle change (https://ecorenovator.org/forum/showthread.php?t=7032)

philb 09-07-19 07:52 PM

Wire feed welder duty cycle change
 
3 Attachment(s)
I was getting pretty desperate trying to get some welding done a few weeks back. My 2 HF wire feed welders refused to weld any more than 2 minutes at a time before shutting down. 102 degF temperature didn't help much either.

The 170 amp one was the newest. I bought it because the old 110A unit would shut down in 2 minutes in 50 degree weather. After blowing most of the dust out of it, there wasn't any change. The 220V fan was pumping plenty of air. I took the cover off 10 minutes after the shutdown. The copper windings were about ambient temp but the transformer and inductor (on top of the transformer) were really warm. There was a heat sink from an old computer handy so it got a new home on top of the inductor with a flat smear across the face and mashed on hard with Plumbers Goop! That small addition was worth an additional 2 minutes. Still not good enough.

The old 110A welder was expendable so it got redecorated with $30 in heat sinks and a more powerful fan off ebay. It welded better than it had ever welded before. I welded for half an hour non-stop without any shutdowns. Yesterday, it was 98 degrees and it welded for three hours with a few 5 minute breaks and to change the wire spool. Who knew?
Two of the photos are turned 90 degrees to the side. I don't know what happened but maybe everyone can see what I did to get greater than 50% duty cycle from their welders.

https://ecorenovator.org/forum/attac...3&d=1567902571

https://ecorenovator.org/forum/attac...4&d=1567902571

https://ecorenovator.org/forum/attac...5&d=1567902571

Daox 09-07-19 08:53 PM

Interesting modification. I'm surprised that those heatsinks made that much of a difference.

philb 09-07-19 09:06 PM

I was surprised too. There is a lot of iron that holds heat in the transformer and inductor.
The 'slots' in the heatsinks are parallel to the airflow from the fan and the fin height was tall as I could fit under the cover.

pr0cess0r 09-09-19 02:08 PM

is there any water cooled welder?

philb 09-09-19 05:10 PM

I'm not aware of any water cooled welders. It's possible though. Water and electricity usually doesn't mix unless there are special provisions made. If I were going down that path, I'd try submerging it in mineral oil. I have a really old xray machine that has its coils submerged in oil.

The next step for me will be a DC capacitor to smooth the arc. Lincoln Weld arc 100 uses that setup. I don't think They were made to resonate. Maybe someone who knows will chime in.

The unit has been running 30 degrees F above ambient since the addition of heat sinks so there's no need in going further with cooling. I used a HF temperature laser to check it immediately before and after welding. This is still hard for me to believe that heat sinks actually made such a difference especially with no heat sink compound. I guess that's why necessity is the mother of....

Daox 09-09-19 07:15 PM

TIG welders commonly have water cooled torches, but I'm not sure about the welder transformers.

oil pan 4 09-10-19 04:13 PM

Welders use bigger transformers and bigger fans for more duty cycle.
The largest one I have seen was a 600 amp welder powered with 480v single phase. It would run continuous up to 400 amps. It weighed around a ton.
I don't event think it had a fan, just used convection.

Cheap little welders can have like a 5% duty cycle at full power.

philb 09-10-19 05:33 PM

Thanks Oil Pan. That confirms what I was thinking. Cooling depends on how fast the welder transformer can dissipate heat. I2R almost always = heat. That's key no matter what size it is.

I googled transformer cooling and saw how the power companies do it. Heat sinks first, then mineral oil buckets for higher heat, then both for huge transformers. Those companies had also rather transport lighter transformers and cool them down than having a heavy one that will take an electric pole down. Those websites also share the math, which I didn't do for this experiment. If it didn't work, then I'd strip it for parts.

CrankyDoug 09-11-19 10:17 AM

Production line welding heads are sometimes watercooled. I've never seen a portable or stand-alone power unit with water cooling other than for TIG torches.

I am surprised there aren't any capacitors in your welder. My 300A Lincoln has six rather large electrolytics. 50 years ago it was common to use inductive filtering for DC supplies because large capacitors were very expensive. Inductor prices have since then skyrocketed whereas caps have become inexpensive. Yours is the first MIG I've ever seen without them.

oil pan 4 09-11-19 10:38 AM

HF welders tend to lack components found on higher end machines.


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