GMAW-P Getting the settings right

By TimGary (****)

Date 07-26-2019 20:09

So the Power Wave S500 is a sweet machine, with multiple pulse waveforms - Rapid Arc, Rapid X, etc.
Each has it's own fit for different circumstances.
For Sch 10 SS pipe, the best pulse waveform to use would be STT, which was made as a quicker / more efficient replacement for GTAW of open root pipe welds. However, this requires a separate module to be added to the power source on Lincoln's Power Wave equipment.
You didn't say which wire diameter you're using. Sch 10 can be done with .035, but you may want to tune down a size or two.
You can use Rapid X or the straight pulse waveform if you don't have the STT module (Rapid Arc is more for structural thicknesses).
I recommend using Lincoln's Red Max wire with 98%AR and 2% Oxy shielding gas.
A trim setting just above mid range is good for eliminating spatter, just below mid range is good for gap filling.
WFS depends on wire diameter and material thickness, and also controls amperage.
As a general rule of thumb starting point, 1 amp for every .001" material thickness. ( 1/8" = .125" = 125 amps)
Choose the WFS that provides the amps you need for the thickness you're welding on, less if your gap filling or open root.
Average actual Amps and volts are shown on the digital readout on the machine while you're welding and for a few seconds after you break the arc.

https://www.lincolnelectric.com/en-us/support/process-and-theory/Pages/pulsed-mig-detail.aspx

Tim

By LToca85 (**)

Date 07-29-2019 11:17

Thank you Tim, I did try the Trimix and i found to like the 98/2 better. I was only using regular pulse but will definitely give Rapid X and STT a go.

By LToca85 (**)

Date 07-29-2019 21:27

Tim thank you for the STT suggestion, when I had it at regular Pulse WFS of 240 the Amps were at about 115 120. The issue I had was that it would make the root pass and the cover pass all in one. I loved the penetration it gave me but the cover was not at all pretty. With the STT I was able to run the root pass and still have enough space to lay a cover FCAW pass. To me that looked much better and the penetration was better than the regular Pulse. We are indeed running .035 wire for both the GMAW and the FCAW. Now I just have to wait a few years before we actually get a job where we can use it lol

By TimGary (****)

Date 07-30-2019 11:49

One of the main concepts behind Lincoln's STT, or Miller's RMD, is that you can use that waveform for the root pass, then switch to another waveform, like Rapid X, or Accu-Pulse for the fill and cap. This means no need for down time to change fillers or process. Just switch programs and you're ready to go. This machine can be set up so that changing programs is as simple as a quick pull and release on the gun trigger, so the Welder doesn't have to work the controls on the machine panel.
Not sure why you changed to FCAW for the cap...

Tim

By LToca85 (**)

Date 07-30-2019 11:59

Mmmm that does sound interesting. I might have to go back and give that a go. We have dual feeders on the Powerwave so we have the GMAW wire in one and the FCAW on the other, I love it you just press the trigger on a gun and boom it switches the program from GMAW to FCAW with out the welder having to press any buttons. I just set the machine for him on both guns and boom he just goes without having to deal with all those buttons witch at first can be overwhelming.

By TimGary (****)

Date 07-30-2019 14:35

For clarification -
A trigger push can change between programs using the same wire through the same gun.
If you want to changes wires, grabbing the dual or other gun will be necessary.
However, the Welder can weld with pre-set trigger controlled programs with either gun, without having to push buttons on the machine. It should automatically switch to whichever gun the trigger is pulled.

Tim

By LToca85 (**)

Date 08-02-2019 12:01

Tim I did see the trigger push program but the reason we went with the FCAW cap is that with the GMAW cap it looks kinda ugly. I am not sure if we just aren't getting the travel speed right or the settings on the machine right for the cap. I can Email you a couple of pics if you like I tried posting the pictures and failed lol

By TimGary (****)

Date 08-02-2019 14:33

I recently qualified some groove and fillet procedures on 304 SS, 12 gage sheet.
I'm using Miller's Accu-Pulse waveform with tuning for Stainless, which is very similar to Lincoln's Rapid X.
During the process, I tried out different gasses and wires to find which runs smoothest.
98% A / 2% O2
90% He / 7-1/2% Ar / 2-1/2% CO2
90% A / 10% CO2
Lincoln ER308LSi - Blue Max and 308LSi - Red Max in .035 dia.
The Red Max is a new wire they have out specifically blended for better wetting characteristics with GMAW pulse.
The Lincoln Rep recommended 98%A / 2%CO2 for the Red Max, but I didn't have any of that at the time

For typical SS that needs best corrosion resistance properties, I found the 98% A / 2%O2 and Red Max wire worked best.
But, I wound up with the 90%A / 10%CO2 - Red Max combo, because:
- Our product is to be acid cleaned, e-coated and top coated, so I'm not worried about how the extra CO2 will affect the corrosion
prevention properties
- This combo offered the best weld fillet weld profile and puddle control-ability.
- The Bends and tensile came out fine

In the past for structural stainless, I found that Metal Core wire worked even better than flux core, but that was before I started using GMAW-Pulse capable equipment.

I guess the point is that, no matter which process or material you're welding, it takes some R&D to figure out the best parameters to suit your need, with the equipment you have available.
Personally, I find that the new GMAW-Pulse equipment that offers multiple waveforms can readily be fine tuned for just about any use.

Tim

By LToca85 (**)

Date 08-05-2019 12:58

Thank you Tim I will definitely keep working on it. That Redmax wire seems like an interesting to try I might have to order a roll so I can try it out.

By LToca85 (**)

Date 09-06-2019 21:17

Tim so I ordered the redmax wire you suggested and it just got to my shop today i will have to let you know how it goes once we get a chance to try it out..