[RDomeij]

Hello Welders,

I recently purchased a TIG welding machine [Miller 161 STL] that has automatic post-flow. The post-flow apparently can't be adjusted.

My problem with this-- it sets the post-flow time based on your amperage. So if I'm making a tack, and I gun the amperage at 160A for a half-second, it will give me 12 seconds of post-flow! I really don't need that, and it's costing $$$.

I don't have any experience with machines like this, so I thought I'd ask here. I don't think closing the shutoff valve on the argon tank every time I make a tack is the proper way to do things... Haha...

Thanks a lot for your help

[Oscar]

change your torch to valved TIG torch. That way you can shut off the gas flow in those such situations.

[cj737]

It’s not really that much gas used. Post flow is important for protecting the tungsten and for the weld. Yeah, I get it, a spot tack and 12 seconds seems unreasonable. But you are blasting 160 amps. Your tungsten and weld quality will thank you.

It’s been my observation that most people don’t run enough postflow, and I also see a lack of ore flow constantly. Preflow improves arc stability and initiation by purging the atmosphere directly adjacent to the tungsten.

I run 2 seconds of preflow and at least 9 seconds of post whenever I weld above 150 amps. I have never noticed a change in consumption of argon as a result. Leaky valves and regulators, you bet. But not attributable to pre- and post flow timings.

[v5cvbb]

Thanks cj, I'll increase both of mine a little more. I'm at less 1 pre and maybe 5 post.

[TraditionalToolworks]

Thanks cj, I'll increase both of mine a little more. I'm at less 1 pre and maybe 5 post.

That's not bad, I use similar, and IMO 5 seconds of post flow is a decent amount. If you count 5 seconds after you stop your arc and pull the tungsten away entirely from the weld, the puddle has more than cooled and there is not much more that can be done...I 'spose the time is arguable and people do often use more...I'm not welding NASA parts though and for me to just eliminate the crater and/or discoloration is all I really need. Remember that you need to hold your cup over the weld end in order to even use the argon, so if you pull it away early you're just wasting argon also.

I'll say that I think 12 seconds is high for something you can't adjust. This means that every 5-6 times you press the pedal, for anything, you're using 1 minute of gas. If I didn't have to pay for gas I probably wouldn't care, but even so one can easily discount the overall price of gas as the cost of welding I 'spose.

That setting is even worse than the Lincoln SW 200 it would seem, another machine that doesn't allow you to adjust the post flow. I consider that to be a deficiency in the machine, but who am I to say.

[v5cvbb]

I expect the post flow would be just as beneficial for the tungsten. I can see pre flow helping with the arc.

I'll try both and see what works. I hadn't really considered pre flow much.

As far as the crater goes, that's filler and torch movement isn't it?

[TraditionalToolworks]

As far as the crater goes, that's filler and torch movement isn't it?

I suppose it is, tapering off the amps, swirling the arc around to prevent it, and the post flow of argon I guess is to prevent contamination.

My heads starting to hurt, I'm going out to glue metal together, as my wife would say.

[cj737]

Most of the Miller boxes I’ve used that have auto postflow, allocate 1 sec per 10 amps, max at 10-12 secs. If you bust out 160 amps, I guarantee you that you’d want more than 5 seconds. Weld a little with 3/32 at that amperage, run 5 seconds of postflow, then pull your tungsten. You’re likely to see discoloration and the tungsten is still smoking hot.

[Spartan]

Gas is among the cheapest aspects of the welding process...at least for me. I don't skimp on it. Usually have my post at 8 seconds minimum...more for SS, and my pre at 1-2 seconds for arc stability at light up. A longer pre flow like that also gives you a brief warning that you're about to strike an arc when you're kicking your pedal around trying to get situated and don't intend to arc on something, which can be handy

HOWEVER...I would probably get a little annoyed at 12 seconds post on tacks

[v5cvbb]

You guys are right. Gas is fairly cheap. I have seen some discoloration of the tungsten at times so I'll up the post flow. Primeweld doesn't have exact setting, but it's above 1 sec pre now. I have post flow way up right now checking some amp readings.

[clavius]

I have a Lincoln SW200 that has a similar auto post flow setting. This feature seems to bug a lot of people and did me a bit at first. So I did a little math on the cost of the gas due to this, you can see it 8 or 9 posts into the thread here:

http://forum.weldingtipsandtricks.com/v ... =5&t=10466

Overall, it obviously adds some cost. If you are doing a ton of tack welding it seems even worse. But in the scope of things, it just does not for me add up to be enough to get worked up over. If I earned my living with this machine or ran a fab shop that popped hundreds of tack welds every day, I would probably think differently. But then I would probably not have bought a welder of this class either and gotten a more full featured (and more expensive) machine.

Just my take.

[rick9345]

more gas is wasted kicking pedal around and with false starts to even worry about post flow welding gas..
Gas is a consumable,bargain with supplier for more favorable price, Huge savings!

[Oscar]

Even though gas is a consumable, it is one that can be minimized as an expense. Money saved is money earned. Who wouldn't want to earn more money?