Wire feed welder duty cycle change
 

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

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

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.

is there any water cooled welder?

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....

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

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.

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.

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.

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

HF welders also don't have the electronics Lincoln's and Miller's do. It's just a cheap welder that's light enough to climb ladders and scaffolding in hand. I do prefer the old Ideal Arc welders myself.

After getting under the hood, I realized this machine is just a large, old power supply. It has a multi-tapped transformer, diodes, inductors and capacitors to smooth the wave form. It is very inefficient by today's standards. I'm thinking since the inductor is welded on top of the transformer because it is borrowing some magnetic flux to keep the amperage surge down?

The Lincoln Weld Pac 100 I have adds an electronic board and capacitor the HF doesn't have. Since the Lincoln no longer functions, I'll rob the capacitor. It is a DC 59,000 uf cap, so care must be taken to get the connections right.

I found adding capacitance works great if you run Flux core.

Flux core or stick is all I do. I should get that mod done tomorrow.

My test equipment shows this 40 volt 59,000 uf capacitor at 34,000 uf, which is out of range. I'm going to get another capacitor. There's small difference between the before and after sine wave. It was added before the inductor on the positive side and negative goes directly to the negative side of the lead. This is supposed to be a DC signal so its very very rough.

Use both.
I found that Flux core likes as much capacitance as you can throw at it.
Welders use the default 50k to 60k uf capacitor as a good trade off between solid wire and Flux core performance. With the trade off favoring solid wire and gas.
With nearly 100k uf I can make Flux core welds that are as good looking as solid wire and gas.

I know this thread is a little old, here's another option to consider if the heatsinks do not provide enough cooling: https://www.geek.com/geek-cetera/coo...n-oil-1495403/
Take the fans out and submerge in a 5gal bucket of oil....? Just don't kick the bucket!

Maybe it a factory or shipyard, where they need continuous-duty welders.?.

patrickh99, I have considered liquid cooling but the welder has to be kept as light as I can get it. The welder frequently goes up ladders and scaffolding in my hands.

The heat sinks are working very well. They keep the welder about 30 degrees above ambient temp now.

I ordered 4 capacitors several weeks ago on ebay. They came in and I tested them before instillation. I'm glad I did. They tested out at about 10% of the face value. The seller issued a refund and I'm still hunting for suitable capacitors. They're difficult to find without spending $80 each.

What specs are you looking for on the caps?

Somewhere around two 47,000- 97,000 uf electrolytic capacitors. Screw tops are preferred as it would simplify installation but not absolutely necessary.

I can't believe how light weight the light-duty welders are these days..
I think mine must weigh about 15 pounds. Now I have to do is learn to make good welds!
https://www.homedepot.com/p/Century-...93-1/302139495

Xringer, Does your welder have a switch mode power supply or is it all solid state without large heavy transformers?

Solid State!
 

Yeah, it all solid state and that makes it very light to carry. I hear they have one just like it
for less money at HF, when it's on sale. I saw a comparison video youtube
but didn't watch it yet.. There are a bunch.
https://www.youtube.com/results?sear...y=century+fc90

I picked a HF (Harbor Freight) portable welding table a few months back,
but have not started practicing welding yet. (Due to medical problems).
I'm planning on starting up when the weather isn't so cold..