Trying to understand new procedure.

gnabgib · Wed Mar 25, 2015 5:43 pm

WPS for TIG states; Current and Polarity, dc, -ve to torch and I haven't seen that before. I'm doing stainless, so dc-.
It also lists Arc energy range to 2.5 kj/mm and Voltage range of 11-12V? Both of which I've never seen when talking TIG.

Wed Mar 25, 2015 6:27 pm

Kj/mm refers to your travel speed for a given setting. For tightly controlled heat input. On some ss it is ruined if held above a certain temp for too long.

gnabgib · Wed Mar 25, 2015 6:55 pm

Thanks and is dc,-ve to torch possibly just a technical way of saying dc-?

Wed Mar 25, 2015 8:14 pm

gnabgib wrote:Thanks and is dc,-ve to torch possibly just a technical way of saying dc-?

Yes.

Some newbie weld engineer was trying to use his new vocabulary. All he really said was, "DC-"

Steve S

gnabgib · Wed Mar 25, 2015 9:03 pm

Otto Nobedder wrote:
gnabgib wrote:Thanks and is dc,-ve to torch possibly just a technical way of saying dc-?
Yes.

Some newbie weld engineer was trying to use his new vocabulary. All he really said was, "DC-"

Steve S

Ha!..Thanks Steve, confirms my suspicions. Thinks...Must remember to read between the lines.

Jeff

Wed Mar 25, 2015 9:05 pm

No worries.

Markus · Thu Mar 26, 2015 5:06 am

There should be given the amperage range to follow. For example 70-90 A. That kj/mm is heat input and it's bit weird that it is given if amps are not.

Voltage does affect to the heat input as well, but usually that is not given for hand welding due to change of your tungstens hight. 10 volts refers to very small cap between workpiece and tungsten. Couple of mils or so.

Also how to determine your welding speed and track that in every single weld? Impossible with hand welding...

gnabgib · Thu Mar 26, 2015 5:58 am

Markus wrote:There should be given the amperage range to follow. For example 70-90 A. That kj/mm is heat input and it's bit weird that it is given if amps are not.

Voltage does affect to the heat input as well, but usually that is not given for hand welding due to change of your tungstens hight. 10 volts refers to very small cap between workpiece and tungsten. Couple of mils or so.

Also how to determine your welding speed and track that in every single weld? Impossible with hand welding...

I was given all the details including the amperage range and travel speed, I just haven't included all of that here.

TRACKRANGER · Sun Mar 29, 2015 11:24 am

gnabgib wrote:
I was given all the details including the amperage range and travel speed, I just haven't included all of that here.

It would be great to see all of the settings. Might put everything into perspective a little better for others to follow.
Thanks
Trevor

gnabgib · Sun Mar 29, 2015 4:45 pm

TRACKRANGER wrote:
gnabgib wrote:
I was given all the details including the amperage range and travel speed, I just haven't included all of that here.
It would be great to see all of the settings. Might put everything into perspective a little better for others to follow.
Thanks
Trevor

Well, the procedure was supplied 'In confidence' so if I gave you all the details I might have to kill you

Sun Mar 29, 2015 8:27 pm

gnabgib wrote:
TRACKRANGER wrote:
gnabgib wrote:
I was given all the details including the amperage range and travel speed, I just haven't included all of that here.
It would be great to see all of the settings. Might put everything into perspective a little better for others to follow.
Thanks
Trevor
Well, the procedure was supplied 'In confidence' so if I gave you all the details I might have to kill you

That said, the Kj/mm is an upper heat limit, or travel-speed quantity, as was mentioned by another. Just stick with the WPS amps, and move fast enough you don't make it black, and you should be fine.

Steve S

gnabgib · Tue Mar 31, 2015 6:17 am

That said, the Kj/mm is an upper heat limit, or travel-speed quantity, as was mentioned by another. Just stick with the WPS amps, and move fast enough you don't make it black, and you should be fine.

Steve S[/quote]

Thanks, but I have to admit it's got me in a knot and I'm thinking now of making a micro rotator, because of the small size and it being a critical weld.
Jeff

Tue Mar 31, 2015 7:10 pm

If you build that "micro-rotator", please share what you build!

I envision a variable-speed geared electric drill (Max 500 RPM, DeWalt makes one) with the trigger replaced with a potentiometer, for speeds as low as 5 RPM, clamped in a vise.

Without knowing the specifics of your project, this is the cheapest accurate rotator I can imagine.

Steve S

Tue Mar 31, 2015 9:30 pm

Sewing machine motor. Already has a foot control, and lots are connected via belts and not built in. So easy to adapt.

gnabgib · Wed Apr 01, 2015 2:45 am

I'll probably get a geared 12v servo motor, with maybe 5rpm at the shaft and gear accordingly. Need up to 26mm per minute but next question is that of the return contact. Maybe a small copper arm, spring loaded to maintain contact while the work piece is turning. I think I have the purge attachment worked out.

MinnesotaDave · Wed Apr 01, 2015 9:47 am

A little back ground on heat input may help you determine your speed needed for your weld positioner.
Just solve for "S"

: heat input Kj.GIF (29.01 KiB) Viewed 503 times

TRACKRANGER · Wed Apr 01, 2015 10:24 am

gnabgib wrote:I'll probably get a geared 12v servo motor, with maybe 5rpm at the shaft and gear accordingly. Need up to 26mm per minute but next question is that of the return contact. Maybe a small copper arm, spring loaded to maintain contact while the work piece is turning. I think I have the purge attachment worked out.

"Up to 26mm per minute"?

Just asking. Are you sure that's not missing a zero or something?

If it was e.g. 12mm diameter rotating at 5 RPM, the travel distance would be at least 188 mm per minute.

To get 26mm per minute with a 12mm diameter job, you would need a rotation speed of ~0.7 RPM. While I don't know the diameter being used, it somehow seems awful slow.

This 'secret' job is getting more and more intriguing ...

Trev