Flux Core Requiring High Feed Speed

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mcman56
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Flux Core Requiring High Feed Speed

Post by mcman56 »

I'm an occasional welder so not very knowledgeable or skilled. I just finished a project and it required close to double the feed rate as recommended in the machine manual. The feed rate did seem pretty constant. I suspect this is really telling me something but I don't know what it means. Does this suggest a feed mechanism issue or a power issue? In the past I have always used a setting fairly close to the recommended ones. The welds came out OK...about what you would expect at my skill level.
  • The machine is a Miller Challenger 172 with max output listed as 170 amp
    It was set at the max power of 4 (it has 4 power settings)
    I needed a feed rate of about 80 out of 100, not sure of units. Recommended was 50.
    Wire was 0.035 flux core
    Material was 3 x 6 x 3/16" steel tubing. The whole thing is about 100 lbs so there is a lot of mass to pull heat away
I'm not sure if this is relevant but I also tried an old roll of 0.03 flux core. Penetration was not what it should be and there seemed to be more splatter.
I did not see any porosity. The roll was probably over 20 years old so I don't know if age is a factor. I do live in a very dry climate. I got the same result before and after using the new 0.035 roll so am pretty sure this result was the wire and not me.
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Steggy
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Re: Flux Core Requiring High Feed Speed

Post by Steggy »

mcman56 wrote: Fri May 28, 2021 10:26 am I'm an occasional welder so not very knowledgeable or skilled. I just finished a project and it required close to double the feed rate as recommended in the machine manual. The feed rate did seem pretty constant. I suspect this is really telling me something but I don't know what it means. Does this suggest a feed mechanism issue or a power issue? In the past I have always used a setting fairly close to the recommended ones. The welds came out OK...about what you would expect at my skill level.
  • The machine is a Miller Challenger 172 with max output listed as 170 amp
    It was set at the max power of 4 (it has 4 power settings)
    I needed a feed rate of about 80 out of 100, not sure of units. Recommended was 50.
    Wire was 0.035 flux core
    Material was 3 x 6 x 3/16" steel tubing. The whole thing is about 100 lbs so there is a lot of mass to pull heat away
I'm not sure if this is relevant but I also tried an old roll of 0.03 flux core. Penetration was not what it should be and there seemed to be more splatter.
I did not see any porosity. The roll was probably over 20 years old so I don't know if age is a factor. I do live in a very dry climate. I got the same result before and after using the new 0.035 roll so am pretty sure this result was the wire and not me.
As you dial up the output power of the machine (actually, you are increasing the output voltage—MIG power sources are constant-voltage, not constant-current) you would expect the "burn off" rate of the wire to correspondingly increase. So having to set the wire feed rate at a higher level when using maximum power is normal.

You should know that welding wire's copper coating deteriorates with age, and the flux within the core also deteriorates. My experience has been that a usable life of 12-15 years from the date of purchase should be expected. Old wire may slip as it runs through the welder's feed mechanism, producing inferior weld quality due to the arc length constantly changing. Also, the copper coating plays an important role in assuring solid electrical continuity from the gun's tip to the wire itself. The copper on old wire becomes copper dioxide due to corrosion, which is a non-conductor. Arc stability can suffer, producing an inferior weld.

Flux-cored wire is generally inferior to solid wire-with-gas for welding heavier sections. 0.035" wire at maximum power on a 170 amp machine is a bit on the light side. I'd be using 0.045" wire.

Lastly, most welders have a duty cycle rating that, if violated, will result in the machine overheating and, at best, becoming unstable in operation. At worst, the transformer and/or power semiconductors in the machine could fail due to overheating. Note that the duty cycle rating applies to the gun as well, which can be ruined if overheated.

Your machine's duty cycle when operated at full power is 20 percent. That means during a 10 minute period, a maximum of two minutes of welding time is permissible. Use of flux-cored wire further derates the gun. Making long passes at high power is not recommended with your machine.
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STRR
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Re: Flux Core Requiring High Feed Speed

Post by STRR »

+1 on what BDD had to say.

On another note, buy quality wire! I used up the spool that came with the machine and was worried I had made a mistake purchasing that machine. While I am not a great welder, I can weld and lay down a fairly good bead. The next spool was name brand, and the performance was noticeably better. When done with that spool, I cheaped out and bought off-brand wire. The results were immediately apparent. The machine was fine; the welder was welding like he always did, BUT, the wire was, shall we say; crap. The next spool was Hobart, and I am delighted with it.
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Re: Flux Core Requiring High Feed Speed

Post by ERIE S-1 BERKSHIRES »

Your welder is fine just need to get new .035 flux core wire you should be able 3/16 with no problem!! I have an old Craftsman welder 120 voltage and it has no problem welding1/4 to 3/8 without a problem !! As for Duty Cycles yeah it's 20% but I've gone far beyond that the little welders built like a Sherman tank
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choprboy
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Re: Flux Core Requiring High Feed Speed

Post by choprboy »

I have a Miller Challenger (not the 172, the preceding plain Challenger which had 5 settings). The Challenger's have a few common problems:
1) The brushes in the drive motor wear out, causing you to have to turn up the feed rate to maintain enough drive current.
2) The feed drive shaft brass bushing wears, causing the drive wheel to drop slightly and not fully engage the wire when feeding/causes slipping.
3) The feed clamp has a very limited travel when closed and people often over tighten it (exacerbating #2).

In my case, the feed would become random. Sometimes it feed perfectly, other times it would skip and jerk, or continuously slip and you would have to crank up the feed rate to maintain a usable actual wire speed. I tried new feed rolls, but they made only a slight improvement. My fix was to make up a new feed wheel about 0.050~0.060" larger than stock and magically the feed worked again and the clamp spring pressure was much more consistent.

Also check would be that you are using the correct groove in the feed wheel. The smooth groove is for solid wire, the toothed groove is for flux core wire. Cleaning out the MIG gun liner and/or replacing might also be in order.
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Steggy
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Re: Flux Core Requiring High Feed Speed

Post by Steggy »

Just one more thing, as Columbo would say. Measure the line voltage at the welder while welding at maximum power. You might be in for a disconcerting discovery.
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mcman56
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Re: Flux Core Requiring High Feed Speed

Post by mcman56 »

All of this is great info for me. Thanks.

choprboy -
Even though it is 23 years old, the welder has seen only occasional use so does not have a lot of hours on it. I have had feed issues which seem to come and go. I just have one feed wheel and it is smooth plus marked .023 to 0.035. I do have the original parts list but it does not show any optional feeder wheels. See the attachment. I was just looking at replacing these parts to see if it would help but did not even find the liner on line by part number. Is there a place to look up parts on line by description or family of welder to find these things? How do you find a grooved wheel?

Ir is interesting that you mention a larger diameter drive wheel because mine has always looked low. I have to push the wire down into the groove when closing the tensioner. I found a piece of split flux core wire in my new roll and assumed it was a manufacturing defect but maybe I had too much tension and crushed it. I did back off on the tension. Is your wheel mild steel? Is the groove a radius or a V? Can you make one to work with more than one wire diameter? Any guidelines?

I did not realize that solid wire degraded with age so will have to start dating rolls. How do you measure voltage? Is it wire to ground clamp?
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choprboy
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Re: Flux Core Requiring High Feed Speed

Post by choprboy »

Looking at the Challenger172 manuals... the pictures are really ratty... Here is the roll picture from the Challenger manual which shows the 2 grooves, one groove is notched, the other is smooth. You just remove the set screw and flip the roll on the shaft to use the other groove.
Challenger_roll.jpg
Challenger_roll.jpg (5.22 KiB) Viewed 12933 times
It looks like the Challenger172 had 2 different drive rolls, it was originally part 165603, but was later changed to part 090423. Perhaps the earlier version only had one groove? The later is the same drive roll as used in the Miller 130XP/150/185, so it should be pretty available at parts stores. EDIT: Found a clearer manual and a third party store with the 165603 part and it does appear to show a single groove. The 090423 replacement also appears to be a single groove? I could have sworn the all the Challengers and the 130XP/150 used a dual groove roller, but apparently not? Ouch on the price...

I made my replacement roll out of plain mild steel with a V groove in it. Hardened would probably be better, but it probably doesn't see enough use to warrant. The groove is a simple sharp V, it doesn't need to be deep, just enough to hold ~1/4-1/2 of the wire diameter to keep the wire in place (and setting the groove in line with the feed helps immensely). The traction is really done by the friction between the upper and drive rollers. It was extremely easy to make on the lathe in a few minutes, center hole with a slightly snug hole to the shaft, outside diameter a bit larger than the stock (this was a bit of a guess), part off and drill/tap a hole for a set screw. I made a few different grooves of various depths in my replacement, but ended up using the shallowest as it seemed to give the best grip.
IMG_4338s.JPG
The Challenger172 originally used the 10A or M-10 MIG gun (the Challenger used the M15). The replacement for that is the M-100 MIG gun or M-150 depending on serial number. According to the 2021 parts guide, the M-100 is now apparently replaced with the MDX-100. The liner kit for the M-10 MIG gun is 194010 for .023/.025 or 194011 for .030-.035, which are both readily available. For the old 10A the part number was 129178 for .023-.030 and 129179 for .030-.035, which don't seem to be available any longer

See the official Miller Parts Guide for the latest numbers. Miller tends to be extremely good with making all their manuals and replacement part numbers available. The Challenger172 shares a lot of parts in common with the later Millermatic models, so other than the 10A MIG gun, most replacement parts can be found:
https://www.millerwelds.com/-/media/mil ... .pdf?la=en

If your MIG wire is splitting it is definitely bad. The wire shouldn't be able to be crushed in the rollers. I would start by blowing out the MIG gun liner, put in a new good roll, check that there is a gap between the tension arm and drive base so the spring has some action, and make sure the polarity is set right (DCEN for flux core, DCEP for gas). When you feed the new roll, I would first lay the MIG gun out flat and feed by hand, it should slip thru fairly easily with only a small constant drag up to the tip (which will be harder to initially push thru, then easy again). Pull it back out and feed in with the drive. If there is skipping or hard places to push in the gun it may be a bad liner.
Last edited by choprboy on Sat May 29, 2021 1:27 pm, edited 1 time in total.
choprboy
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Re: Flux Core Requiring High Feed Speed

Post by choprboy »

Welding voltage would be wire to ground clamp (or feed stud to feed stud at the polarity bus bars in the feed mechanism) and is only live when the the trigger is depressed (so you should really pull the wire out if testing so you don't arc/accidentally weld at the same time you are measuring). But I think BigDumbDinosaur meant measuring house line voltage when welding, expecting a significant drop. The Challengers are 220V, so its not nearly as much of a problem as the 120V welders out there.
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Steggy
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Re: Flux Core Requiring High Feed Speed

Post by Steggy »

choprboy wrote: Sat May 29, 2021 1:21 pmBut I think BigDumbDinosaur meant measuring house line voltage when welding, expecting a significant drop.
Correct.
The Challengers are 220V, so its not nearly as much of a problem as the 120V welders out there.
It shouldn't be a problem, but if the line is a long run with smaller gauge wire, the voltage seen at the welder will take a big tumble under load, especially right at the moment the wire makes initial contact with the work to strike the arc.

Upon examining the machine's wiring diagram, I see it has a pretty basic power supply with no active regulation—just a filter capacitor and a stabilizing choke. It won't behave well if the line voltage sags while welding. Furthermore, the unit appears to not have any power factor correction, and based upon the published specs, the full-load power factor is 0.85 (KVA rating is 4.49 and KW rating is 3.83).

What that means is the instantaneous full-load current flow per AC half-cycle is about 15 percent higher than the full-load RMS rating of the machine. The wiring has to be sized to account for the instantaneous current flow, not the full-load amperage rating. Miller's recommendations on page 13, section 3.4, really aren't adequate unless the machine is right next to the panel supplying the power.
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mcman56
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Re: Flux Core Requiring High Feed Speed

Post by mcman56 »

Thanks for this detail but I'm not sure I'm following. This machine does have the 10A gun. Are you saying the M-10 liner will fit? Or is it that a liner to fit the 10A is obsolete and I would have to purchase a new gun?

"The Challenger172 originally used the 10A or M-10 MIG gun (the Challenger used the M15). The replacement for that is the M-100 MIG gun or M-150 depending on serial number. According to the 2021 parts guide, the M-100 is now apparently replaced with the MDX-100. The liner kit for the M-10 MIG gun is 194010 for .023/.025 or 194011 for .030-.035, which are both readily available. For the old 10A the part number was 129178 for .023-.030 and 129179 for .030-.035, which don't seem to be available any longer"
choprboy
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Re: Flux Core Requiring High Feed Speed

Post by choprboy »

I was saying, if you have the 10A gun, Miller considers it obsolete and doesn't list parts for it any longer. The replacement for the entire MIG gun would be the M-100 or MDX-100 now. The 10A uses a different liner than the M-10.

Looking again, several third parties do actually list as having the 10A liners it in stock... though places like WeldFabulous show it as having a 2 week ship time which usually means they are drop shipping it from Miller and it probably won't actually ship. I found Flint Welding Supply who says they have 1 in stock, so there might be some actually out there still.
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