EP or EN Start When Tig Welding Aluminum?

dynasty200sd · Fri Nov 27, 2015 6:31 pm

As my forum name, I have a Miller Dynasty 200 SD.

What I am wondering is, whether I should use EN (electrode negative) or EP (electrode positive) when initiating the arc to tig weld aluminum? In regards to EP, will it be benefiting to get the cleaning action of it on start due to the necessity to break apart the layer of aluminum oxide atop the aluminum versus starting with EN?

LtBadd · Fri Nov 27, 2015 9:23 pm

I haven't messed with this option before, isn't this timed in micro seconds? Will be interested in the responses, just guessing it isn't too critical but I have been wrong before

May be buying a Dynasty 210DX so I am curious also

Richard

dynasty200sd · Fri Nov 27, 2015 9:57 pm

LtBadd wrote:I haven't messed with this option before, isn't this timed in micro seconds? Will be interested in the responses, just guessing it isn't too critical but I have been wrong before

May be buying a Dynasty 210DX so I am curious also

Richard

For my Dynasty 200 SD, start polarity is in milliseconds. On a side note, I do not have pulse or sequencer controls due to not being the DX model.

Oscar · Sat Nov 28, 2015 12:30 am

It's going to be swtiching so fast that I doubt it would make a difference.

On a side note, I had no idea there was a setting to set which polarity to start the arc with, on a Dynasty(!). I just always assumed that with AC welding, EN-half comes first, then it switches after that from then on. I know you can always reverse the leads, but a setting?

Perhaps you can answer your own question. Try it both ways and tell us what (if any) differences you can quantify/measure/observe.

zank · Sun Nov 29, 2015 11:26 pm

Always EP for easier starting on AC. Think of the tungsten as a lightning rod.

soutthpaw · Mon Nov 30, 2015 12:53 am

dynasty200sd wrote:
LtBadd wrote:I haven't messed with this option before, isn't this timed in micro seconds? Will be interested in the responses, just guessing it isn't too critical but I have been wrong before

May be buying a Dynasty 210DX so I am curious also

Richard
For my Dynasty 200 SD, start polarity is not in milliseconds, but start amperage and start slope is in milliseconds. On a side note, I do not have pulse or sequencer controls due to not being the DX model.

If you buy the pulse board you can easily upgrade your machine to DX. At least that's what has been said here

AFR_Autoworks · Mon Nov 30, 2015 6:41 pm

I am glad I came across this! I was wondering the same thing when I first purchased my 200DX. I just left it as the default setting which I believe was EP. I would be curious to see if anyone has any input on starting with EN?

dynasty200sd · Sun Dec 13, 2015 12:25 am

I found this information in Miller Electric's Booklet Guidelines to Gas Tungsten Arc Welding (GTAW)

3-1 Arc Starting Methods

EP Starting
- Preheats tungsten
- Compensates for frosting
- Repeatable Starting
- "Cleans" work on starts
- Can damage tungsten tip
- Good for AC TIG

EN Starting
- Susceptible to frosting
- Repeatable starting
- No cleaning on starts
- No damage to tungsten
- Preferred for precision DC
- Acceptable for AC

Oscar · Sun Dec 13, 2015 11:52 am

dynasty200sd wrote:I found this information in Miller Electric's Booklet Guidelines to Gas Tungsten Arc Welding (GTAW)

3-1 Arc Starting Methods

EP Starting
- Preheats tungsten
- Compensates for frosting
- Repeatable Starting
- "Cleans" work on starts
- Can damage tungsten tip
- Good for AC TIG

EN Starting
- Susceptible to frosting
- Repeatable starting
- No cleaning on starts
- No damage to tungsten
- Preferred for precision DC
- Acceptable for AC

Wait, what? I guess I'm confused as to what is being discussed here. Are we talking about the actual welding arc initial polarity, or just that of the High-frequency start-arc?

zank · Sun Dec 13, 2015 12:12 pm

Actual welding.

Oscar · Sun Dec 13, 2015 12:35 pm

So how can you have "EP starting" if you're welding in DCEN?

zank · Sun Dec 13, 2015 1:31 pm

It's a computer. It can do whatever it can be programmed to. You are talking the first quarter of a second or less.

Oscar · Sun Dec 13, 2015 2:21 pm

Ah now that makes more sense. Is this part of the Blue Lightning feature?

zank · Sun Dec 13, 2015 2:28 pm

It was part of the start programming pre-blue lightning iirc.

rick9345 · Sun Dec 13, 2015 5:00 pm

An available gimmick(because of the software) or is it a useful tool?

dynasty200sd · Sun Dec 13, 2015 5:15 pm

I do not know the history behind arc starting polarity either, but I originally started this topic due to having the option in the advanced settings of my Miller Dynasty 200. Fast forward to lastnight, I came across this booklet put out by Miller Electric showing the differences.

As to whether EP or EN start, this would be options for welding in AC; and is during the start of the cycle. The amount of time in the start polarity would then be dependent on the frequency the machine is set to (i.e., 60Hz 1/120th of a sec in the start polarity, 120Hz 1/240th of a sec, 250Hz 1/500th of a sec, et cetera). These times of course would be with a balance of 50/50 EN/EP.

zank · Sun Dec 13, 2015 5:26 pm

On the 280DX, the start time is independent of AC frequency. If you set it at 250 ms, it stays at the programmed start current for that duration of time and then it goes into the cycle. Is the 200 different?

Being able to dial in the start parameters isn't a gimmick. I don't adjust them often, but it has helped me in a number of situations.

dynasty200sd · Sun Dec 13, 2015 10:05 pm

zank wrote:On the 280DX, the start time is independent of AC frequency. If you set it at 250 ms, it stays at the programmed start current for that duration of time and then it goes into the cycle. Is the 200 different?

Being able to dial in the start parameters isn't a gimmick. I don't adjust them often, but it has helped me in a number of situations.

I'm referring to start polarity, not start amperage / current.

So, if you have a frequency of say 200 Hz, you have 200 cycles per second which I'm sure you have an understanding of this. Since one cycle of alternating current is from positive to negative and back to positive to start the next cycle; you'd then have 200 half-cycles of negative, and 200 half-cycles of positive per second. This is of course if the balance is set to 50/50.

If say the balance was set to 70/30 (EN/EP) for the same frequency of 200 Hz; then you would have 280 half-cycles of negative, and 120 half-cycles of positive per second.

This is what I was referring to in my previous post; so a 200 Hz frequency with a 50/50 balance, the amount of time in the chosen start polarity would be for 1/400th of a second.

With the same frequency of 200 Hz, but with now a 70/30 (EN/EP) balance, the amount of time in the start polarity if it was EN would last for 0.7/200th of a second (3.5 milliseconds). If the start polarity was instead EP, the amount of time in EP would be for 0.3/200th of a second (1.5 milliseconds).

zank · Sun Dec 13, 2015 10:17 pm

When you program the start parameters on a dynasty, the machine goes through that program before going into the welding program. You set start polarity (EN or EP), start amps, start time (0-250 ms), start slope time (0-250 ms). Whether you are in AC or DC welding, you can set start polarity at EN or EP. You then set the start current (usually higher than your welding current). The start time is then set at how long the machine stays at the start current, and then set the slope time to determine how quickly the machine slopes to your welding current. When the slope time is over, the machine goes into your AC or DC welding parameters. So the welding AC frequency does not determine how long the machine stays at the start parameters. I hope that makes sense. This stuff can be a challenge to explain well.

dynasty200sd · Mon Dec 14, 2015 1:32 am

zank wrote:When you program the start parameters on a dynasty, the machine goes through that program before going into the welding program. You set start polarity (EN or EP), start amps, start time (0-250 ms), start slope time (0-250 ms). Whether you are in AC or DC welding, you can set start polarity at EN or EP. You then set the start current (usually higher than your welding current). The start time is then set at how long the machine stays at the start current, and then set the slope time to determine how quickly the machine slopes to your welding current. When the slope time is over, the machine goes into your AC or DC welding parameters. So the welding AC frequency does not determine how long the machine stays at the start parameters. I hope that makes sense. This stuff can be a challenge to explain well.

After reading over your reply I've quoted above, and looking over my Dynasty's manual once more; I see what you're explaining. At first in my mind I was figuring during the TIG start, if the machine was set for AC the polarity would be switching from negative to positive or vice versa from the get go.

If I am understanding it correctly now, going by the TIG Start Parameters' Drawing in my Dynasty 200's manual; is the amount of time the Start Polarity lasts for is however long the Start Time is set for, or is it until the end of the Start Slope TIme?

I'm guessing it's until the end of the Start Slope Time.

zank · Mon Dec 14, 2015 7:46 am

You are correct. The programmed start polarity stays until the end of the slope time. Then the machine switches to the AC or DC welding parameters.

rick9345 · Mon Dec 14, 2015 8:40 am

Thanks "ZANK" for explaining more than a gimmick for speciality situations. For your demonstrated skill level it would be useful.

This forum gets useful info to masses and those willing to experiment. Thanks to those who contribute.
The info even helps a stone age welder like me.
Seems once upon a time the operator had more skills than welder,now with the electronics available the welder has more skills, and the operator has to catch up.
I still use a rotary phone.

zank · Mon Dec 14, 2015 8:51 am

My pleasure! I'm happy when I can help put something useful in the hands of somebody who will use it.