Tig Post Flow Time

A

atomarc

Diamond

Joined

Mar 16, 2009

Location

Eureka, CA

• Jan 22, 2012

• #1

I have an old Cyber-Tig that allows post flow time adjustment. On aluminum, many folks say 1 second post flow for each 10 amps of welding current.

This seems WAY overboard to me...do I have my head where the sun don't shine or does this sound correct. I am using a water cooled torch (20).

Stuart

 

A

altered

Aluminum

Joined

Apr 2, 2007

Location

Qc, Canada

• Jan 22, 2012

• #2

For welding aluminum I set the post flow to a minimum as aluminum is not very reactive with oxygen. With aluminum use a moderate gas flow about 15-20 with a very good torch angle.

 

A

atomarc

Diamond

Joined

Mar 16, 2009

Location

Eureka, CA

• Jan 22, 2012

• #3

So what's your minimum? I dialed mine down from 4 seconds to 2 seconds. I sort of got the idea part of this post flow was to protect the hot Tungsten with inert gas until it cooled a tad.

You can see that I'm a green pea when it comes to TIG welding.


Stuart

 

David Ferguson

Cast Iron

Joined

Aug 13, 2008

Location

Paso Robles, CA

• Jan 22, 2012

• #4

The idea is to protect the puddle while it cools. It only needs to flow long enough for the puddle to solidify.

If you start to notice that the post flow stops before the puddle solidifies, then increase the post flow time.

As a welder, the important technique to develop is to continue to hold the torch over the puddle while the post-flow is happening -- it doesn't matter what the post-flow is set to if you move the torch away immediately after releasing the pedal!

 

A

atomarc

Diamond

Joined

Mar 16, 2009

Location

Eureka, CA

• Jan 22, 2012

• #5

David,

That sure makes sense to me, protect the molten puddle from atmosphere. I wonder why Miller (welders) talk about the 1 sec/10amps formula...at that rate my tank of Argon would be gone in nanoseconds.

Stuart

 

K

kustomizingkid

Titanium

Joined

Aug 2, 2010

Location

Minnesota

• Jan 22, 2012

• #6

Depends on the material and thickness... Stainless, titanium and any other metal that is sensitive to atmospheric contamination go with a long post flow. Steel, chromoly, aluminum shorter... That is when amps are dependent. The rule of thumb is when you stop welding the post flow should be long enough that the tungsten is sheilded. If you stop and the tip of the tungsten turns blue you need longer post flow, the tungsten should remain the color it started out brand new when welding.

 

D

dgcope

Cast Iron

Joined

Feb 7, 2003

Location

Athens GA USA

• Jan 22, 2012

• #7

I have found that shielding gas flow rates and post flow times are often stated at wildly higher than necessary values. I think the gas supply companies promote these myths to keep selling you more bottles of expensive shielding gas. As recommended in above posts, you can find the ideal post flow via experimentation for any given amperage and material.

Best,

Don

 

S

SND

Diamond

Joined

Jan 12, 2003

Location

Canada

• Feb 11, 2012

• #8

You also don't want the tungsten to go black, it needs to cool down just like the puddle, and so does the end of the filler which should be kept shielded as well.
at 100-150amps I use 5 to 7 second post flow, generally 10 seconds for 200amp.
I always leave it around 10second when doing aluminum as well mainly because of excess heat in the tungsten. Some jobs I have to use 20-30 seconds, and also adjust the pre-flow accordingly. There's no set rule for it, use what it requires, if anything goes the wrong color you probably don't have enough shielding.

 

J

jamie76x

Hot Rolled

Joined

Nov 26, 2011

Location

Pittston, pa

• Feb 11, 2012

• #9

I personally pay for my argon, therefore I try not to waste it. You really only need the post flow to protect the puddle for a second after the weld stops, if that. If your holding the argon on the weld after you stop to keep a nice color, maybe 4 or 5 seconds the most.

I just checked my machine, Post flow is set on 10 seconds. I rarely change it. I always went by the " if the tungsten is cool enough to touch with my finger, I don't need the argon anymore to protect it. 10 seconds seams to me long enough to cool it down on 3/32"

 

A

adama

Diamond

Joined

Dec 28, 2004

Location

uk

• Feb 12, 2012

• #10

Whilst i don't tig much alu on steel or stainless i find 2-3 seconds at 100amps plenty on a air cooled torch. Heck forget the argon costs, think of the wasted time. Life's only so long!

 

N

Newman109

Diamond

Joined

Sep 4, 2006

Location

Sacramento County, California, USA California

• Feb 12, 2012

• #11

atomarc said:

David,

That sure makes sense to me, protect the molten puddle from atmosphere. I wonder why Miller (welders) talk about the 1 sec/10amps formula...at that rate my tank of Argon would be gone in nanoseconds.

Stuart

Click to expand...

That does seem to be too much. What others say here is correct...you only really need post-flow until the puddle cools. On my Syncrowave 200, the auto post-flow function gives 1-5 seconds for each 10 amps from 10 to 50. After that, it adds a second for each 10 amps up to 200. That would be 20 seconds! Since like some others I pay for my own argon, I use the manual setting, anywhere from 1-25 seconds, and keep it short so as to save gas.