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Taking a different approach to independent EN and EP amperag

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Taking a different approach to independent EN and EP amperag

Postby zank » Fri Nov 21, 2014 4:07 pm

I've been doing some experimenting on my machine and wanted to share my findings in hopes that it might help some others. When I was in the process of deciding between the Dynasty 350 and Dynasty 280DX, one of the things that kept me coming back to the 350 was independently adjustable EN and EP amperage in AC. The 350 was a real reach for me financially though. When I heard that Miller was going to put out an expansion for the 280DX that implemented this feature, I decided to go with the 280DX and wait it out for the expansion.

First, a quick overview of what this feature actually is. Most weldors are familiar with balance and frequency adjustment. Balance is the percentage of time that the machine is on the EN or EP side of the wave during each cycle. Frequency is the number of cycles per second that the machine is cycling. So if you are running 75% EN balance and 120 Hz, the machine is spending 75% of the the time on the electrode negative side of the cycle and 25% of the time on the electrode positive side of the cycle and it's switching 120 times per second. By introducing independently adjustable EN and EP amperage, you can dial in the amps on each side of the wave. For instance, you might run 125 amps on the EN side and 100 amps on the EP side. The common approach and what most of the machine manufacturers recommend is running higher EN amps than EP amps to put more heat into the part for deeper penetration and less heat coming back into the tungsten.

When I got the expansion for my machine, I started off by going with Miller's suggestion. I started off with a ratio of 1.5/1.0 EN/EP. In other words, the EN amperage was 1.5 times greater than the EP amperage. The results were not what I was expecting or hoping for. I found I had to turn my balance down to get enough cleaning and that resulted in more tungsten degradation than I was used to (I was running a 3/32" 2% lanthanated). It got me thinking about what is actually going on during the EP cycle and what is really doing the cleaning. Did it have more to do with the amperage or the % balance? I started experimenting with running the EP amperage higher than the EN amperage to understand if it improved cleaning. I was really surprised to find that for my application, the amperage on the EP cycle played a more significant role in cleaning than the time (balance did). I started pushing the limits a bit, and went as high as a 1.0/1.5 EN/EP ratio and a balance of 85-90% EN. Yes, the EP amps were 1.5 times greater than the EN amps. I was able to go down to a 1/16" 2% lanthanated electrode ground to a sharp point. The resulting control was really shocking. It's been as close to feeling like running DC on steel as I've been able to dial in yet. I also found my restarts looked a little nicer and the etching zone was narrower and more faint. In my business, weld aesthetics sells. It really matters. I'm really happy with how the finished product is looking.

Here, I have my EP amps set at 280 amps and my EN amps set at 195 amps. Wave shape was advanced square wave for both EN and EP. My balance was set at 80-85% EN depending on the joint. Welding the sides of the tube goes a little nicer with a bit more cleaning compared to the deeper angles. Frequency was 250 Hz. Running a CK20 torch with a gas lens and #8 cup running at 18 CFH.

Here's the initial prep on the tungsten.

Image
1/16" 2% lanthanated initial prep by Zanconato Custom Cycles, on Flickr

Here's the tungsten after tacking the two front triangles.

Image
1/16" 2% lanthanated after tacking by Zanconato Custom Cycles, on Flickr

Tacked triangles.

Image
tacked by Zanconato Custom Cycles, on Flickr

Tungsten after welding out the front triangles. Now granted, this isn't a ton of welding. But I think it help up amazingly well.

Image
1/16" 2% lanthanated after welding by Zanconato Custom Cycles, on Flickr

Image
Seat cluster by Zanconato Custom Cycles, on Flickr

Image
Bottom bracket by Zanconato Custom Cycles, on Flickr

Image
Head tube by Zanconato Custom Cycles, on Flickr

For reference, the head tube is 2" OD x 0.145" wall. The threaded bottom bracket shell is 1.75" OD by 0.160" wall. The three main tubes vary between 0.052" and 0.074" wall. Material is 7005 aluminum. Filler was 5183.

If you've made it this far, I hope you found the info useful. I'm going to keep experimenting with wave shape and I'll put up more info if people are interested.

I keep coming back to what Dave Powelson has typed quite a few times. There are an infinite number of ways to set up these inverters. I'll add to not get boxed in by the recommendations. Experiment a lot!
Mike Zanconato
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Re: Taking a different approach to independently adjustable

Postby admin » Fri Nov 21, 2014 4:17 pm

Great post Zank. Just because Miller can make a good piano doesn't mean they can play it.

Jody


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Re: Taking a different approach to independent EN and EP amp

Postby zank » Fri Nov 21, 2014 4:22 pm

Thanks boss! Just trying to share the knowledge.
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Re: Taking a different approach to independent EN and EP amp

Postby rick9345 » Fri Nov 21, 2014 4:31 pm

Thanks
very informative and great pictures
Keep info coming

Pat on the back,nice work
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Re: Taking a different approach to independent EN and EP amp

Postby angus » Fri Nov 21, 2014 5:20 pm

exceptional post with great camera shots.

thanks
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Re: Taking a different approach to independent EN and EP amp

Postby ESENTI » Fri Nov 21, 2014 6:50 pm

Zank you are very good well done . I follow and i hope I get close to your welding . One thing only ,what thickness of the welding
rod please ? ( diameter ).My machine is fronius who has a similar adjustment but not exactly different amperage . So i will use this and
i will try to see what happens (it is in the bottom line with the arrow ).
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Re: Taking a different approach to independent EN and EP amp

Postby Otto Nobedder » Fri Nov 21, 2014 9:49 pm

Zank,

That was very enlightening! I've never had a machine with those features, so it's new information to me. The reasoning you provide for your results makes a great deal of sense.

I look forward to further updates as you learn more about your machine and the results it can produce (and why!)

Steve S
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Re: Taking a different approach to independent EN and EP amp

Postby TRACKRANGER » Sat Nov 22, 2014 1:36 am

Thanks Zank for sharing such exact detail, the settings and the results of your experimentation.
My machine has similar features, but I never considered going so far into EP. This is really helpful
Thanks again
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Re: Taking a different approach to independent EN and EP amp

Postby Oscar » Sat Nov 22, 2014 1:56 am

Very good post. I had been meaning to try similar settings on my HTP Invertig221, just never got around to doing so.
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Re: Taking a different approach to independent EN and EP amp

Postby motox » Sat Nov 22, 2014 7:31 am

thanks Zank
i have a htp221 coming so i will be
following this closely
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