Wire speed temperature sensitivity

[Codafile4]

MIG welders with a power source and a seperate wire feed unit are not independently used to control the WFS. a power source which has an output of say 300amps has to be matched to the Maximum input of the wire speed unit, checking the back of the WFU will tell you the maximum input rating (duty Cycle) which may be 250 amps, the power source should then be set at 250amps or slightly under, once this is done then the WFS and the amperage is set by using the WFS knob only, the more amperage the more wire, there is no such thing as a "fine tuner". lowering the WFS loweres the ampage and visa versa there is nothing gained in trying to balance the two controls.
Once you have the amperage set, use the Voltage to "Balance" the two. simply set the amperage/WFS to a required setting, without using anything else, adjust the voltage one step at a time and check the weld bead, continue doing this until you have a weld bead that you require and which the toe of the welds are blended in smoothly with the parent metal.
With a combined power source and wirefeed system the WFS is always used to control the ampage, this is the design of these particular sets.
Make sure that the MIG Torch is capable of taking the ampage, if this is to high then the tourch will burn out and caurse you more problems.
I would not have thought that motor car repairs would use a seperate WFU and Power source unless some heavy duty welding is to be performed so the wirefeed speed and ampage are controled by the one knob on the combined sets

 

[malcolm]

Mine has the wire feed and power source in the same box. While the correct thinking is wire speed controls amps and the setting on the power source controls the volts, in practice for dip transfer if the wire speed is too fast for a voltage setting it will bounce off the workpiece. Too slow and the wire will burn back to the tip. Amp control is thus limited to a fairly limited range for each voltage setting.

I'm forever getting told off for this, but I tend to set the power source to a voltage where I can get some range of control of the amps with the wire feed, then twiddling the wire feed to suit what it is I'm trying to do.

(Actually I don't get told off for that - normally it's for referring to the volt setting as a power setting And for me calling MAG MIG - it's irritating the Norwegains ).

 

[Drains]

the power source should then be set at 250amps or slightly under,

I must confess i'm confused codafile. How do you set the amperage on the power source, and why would you (even if you could) set it to the maximum.

The mig sets I have can only be set by voltage. I can't set the amperage because there is no indication of that, except on the power source, during welding. In addition, the swf units don't show amps - even if the speed control knob has "amps" written under it (rather than speed)

In my experience, a WP for mig indicates voltage and wire speed (amongst other things). You set those, and maybe adjust the wire speed within parameters, and you're there.

So, coda, would you elaborate on your suggestion above, so I can get me head around it?

 

[Drains]

And for me calling MAG MIG - it's irritating the Norwegains ).

Maybe you should start referring to GMAW, and confuse everybody (except the Yanks)

 

[malcolm]

Maybe you should start referring to GMAW, and confuse everybody (except the Yanks)

I reckon MIG is as good generic term as any. Would get a bit fiddly including the MAG, MAGS, GMAW or GMA every time it's mentioned and I'd have to be second guessing what gas people are using. As far as I know it's only the Norwegains that are upset so far.

 

[Codafile4]

MIG/MAG Settings

hi simon, sorry if I have confused the situation, can I start firstly with a power source with everything built in, on the front pannel you have two main control knobs, one indiates the wire feed and the second, the voltage control, some sets have two voltage controls, a course and fine. (I'm ignoring the Spot Stich and Chokes)
The wire feed knob is numbered 1-10. lets start with this first, if the set is rated at 150 amps then No10=150amps and No 5 will be approximately 75 amps and so on, these settings have to be guestimated, if there is no ampmeter attached( an old machine can be 5% either way), (I'm not including the duty cycles at the moment). If you do a weld bead and look at the end of the wire, you will see a small ball on the end, this ball is controled by the voltage, "Pinch effect",
In "Dip transfer" this transfer is when the wire dips into the pool, the voltage "Pinches off a small blobule of wire as it begins it's cycle, and transfers this blobuleto the material, (lobster back ) as you increase the voltage, these blobules get smaller and smaller until eventually it moves into "globuler" then "Spray Transfer".
Voltages for "Dip Transfer" are typicaly 18-25volts, in "Spray Transfer" they are 28-35volts depending of course on the power of the set, a 150 amp may not reach into Spray mode.(look at the duty cycle on the rear of the set, this will give the max/min voltage on the choosen ampage 35% 60% and 100%)As you increase the ampage you have to increase the wire feed speed to get the deposition rate, this is done automaticly. the wire feed is linked with the power (Amps)
If the voltage is too low you get a lot of spatter, as you turn up the voltage this will disapear, Try this- set the WIRE FEED Speed Dial to No 5, Arc volts on say 2, now without moving the WFS run a bead of weld. then set the Voltag up one to No 3, don't touch the WFS, continue this exercise as you go, you will notice that the weld bead widens, flattens and reduces the spatter. Therefore when you move the WFS you alter the power.lower penatration
Now the powere source with a detachable Wire Feed Unit,
These CC type DC power sources have a wide range of amperages 300 , 600 amps, wire feed units also have a wide range 200-300 and even more, when you buy the complete system the WFU will be matched however this WFU may not be capable of pushing cored wire, for instance at 350 amp or more, which means that a bigger unit is reqired as an add on, you may have a Esab power source and want to change the WFU to a Migatronic, these wire feed units have a maximum rateing therefore if you put a 250 WFU on a 350 power source you will get a big problem. Look on the rear of the WFU and you will see the max input for that unit. Most if not all the bigger
sets have an amp meter and a voltage meter, turn up the Wire feed knob and you will see the amprage go up, turn it down and the amprage drops this is typical of all (dare I say) MIG/MAG equipment.
Try the above exercise and lets know how you go on. by the way if anyone has a MIG with no Plate displaying the duty cycles, then Im afraid to say, but its a "Mick Mouse" machine whereby nothing will work properly.

 

[Codafile4]

I must confess i'm confused codafile. How do you set the amperage on the power source, and why would you (even if you could) set it to the maximum.

The mig sets I have can only be set by voltage. I can't set the amperage because there is no indication of that, except on the power source, during welding. In addition, the swf units don't show amps - even if the speed control knob has "amps" written under it (rather than speed)

In my experience, a WP for mig indicates voltage and wire speed (amongst other things). You set those, and maybe adjust the wire speed within parameters, and you're there.

So, coda, would you elaborate on your suggestion above, so I can get me head around it?

All MIG sets have the Wire speed which also links the amprage, Turn up the wire feed speed and you increase the amprage try the little exercise in my last post

 

[Codafile4]

I must confess i'm confused codafile. How do you set the amperage on the power source, and why would you (even if you could) set it to the maximum.

The mig sets I have can only be set by voltage. I can't set the amperage because there is no indication of that, except on the power source, during welding. In addition, the swf units don't show amps - even if the speed control knob has "amps" written under it (rather than speed)

In my experience, a WP for mig indicates voltage and wire speed (amongst other things). You set those, and maybe adjust the wire speed within parameters, and you're there.

So, coda, would you elaborate on your suggestion above, so I can get me head around it?

I take it that you are talking about a Welding Procedure ? take another look and you will see that it contains AMPS, VOLTS and TRAVEL SPEED (Judged by the wire run out length) these three are calculated for heat input ie K/joules

 

[Codafile4]

power settings

I take it that you are talking about a Welding Procedure ? take another look and you will see that it contains AMPS, VOLTS and TRAVEL SPEED (Judged by the wire run out length) these three are calculated for heat input ie K/joules
Can I add that not all power sources have a amprage dial those that dont are pre-set, some however are used for other add ons like Carbon Arc Cutting and Arc Welding where control of the amprage is required.

 

[Codafile4]

I'm baffled. My little welder is one of the type that adjusts wire speed with voltage setting. It used to be that I could set it to about 5.5 on the dial and weld happily all day on any voltage setting.

It still likes to start off at about 5.5, but after about 2 inchs of welding it prefers to be nearer 5 (making it tricky to weld small pipes), and by the time I've welded around a foot (in distance) it wants to be at about 4 where it settles down and is happy.

My thought was resistance in cable joints, but the thing is only 1 year old, and I've had all the joints apart and back together and no difference. Checked resistance all over the place and there doesn't seem to be a high resistance anywhere.

I'm completely baffled! Is there anything electrical that might cause this sort of thing - or any control measures that might be added to get around them? Or should I keep looking for bad connectors or dry solder joints?

Small pipe, the heat of the arc will make the steel more "plyable" and you will have to lower the amps as you move around the joint, try the same exercise on a plate which is wider this will disapate the heat.

 

[malcolm]

Small pipe, the heat of the arc will make the steel more "plyable" and you will have to lower the amps as you move around the joint, try the same exercise on a plate which is wider this will disapate the heat.

If only that were the trouble . In fact my wire speed doubles after a couple of minutes welding presumably indicating a welder fault. Not so handy. Going to try a pulse width controller for the wire speed at the weekend (unless I can get a head gasket - then I'll be fixing the Renault).

 

[Codafile4]

All MIG sets have the Wire speed which also links the amprage, Turn up the wire feed speed and you increase the amprage try the little exercise in my last post

Hi Simon, Just seen you FRC300 power source and your wire feed unit, this is an "Add on" to a MMA + power source and due to this and the age of the equipment you are quite right, you do set your amps from the main power source then use the wire feed speed to suit, my apologise. should have got all the information on the set before shouting my mouth off !. however you will find that on a "matched pair" the amps are connected to the WFS. The good thing with these type of power sources is, they can be used with MMA, add on TIG units, etc.
modern units allow you to move the WFU as far as the cable+torch will allow thus all the controls can be set on the job instead of running back and forth to alter the amps.
and or the voltage.

 

[Codafile4]

If only that were the trouble . In fact my wire speed doubles after a couple of minutes welding presumably indicating a welder fault. Not so handy. Going to try a pulse width controller for the wire speed at the weekend (unless I can get a head gasket - then I'll be fixing the Renault).

either way, good luck.

 

[oddball90]

Malcom did you change the circiut board or is this another mod to try and cure increasing wire speed.

 

[malcolm]

I'm sure a new PCB would sort it (as it didn't have this problem from new), but struggling with Christmas post still. Will see if Steve will send another when he gets back on the forum. In the meantime I'm keen to see what the PWM board does.

 

[oddball90]

Not off snow boarding again is he?

 

[shenion]

Malcolm, the PWM board should do OK, but it has no feedback for the speed. It will vary with load on the motor. Will not be as bad as an unregulated circuit like a SIP.

A better controller will regulate the back EMF of the motor (measured during the dead time of the PWM.) Another method is to measure the current draw and increase the PWM as needed; this usually requires trimming as it needs to match the resistance of the motor.

 

[malcolm]

Some feedback on this. The board was repaired by the Portamig boffins - just a little blue capacitor replaced. And that's fixed it.

The wire speed still increases cold to hot, but only by about 15% rather than the 100% previously (which might be intentional as you need a little more wire when you get going). No need to alter the settings during welding.

It's back to it's old self again. Thanks Steve. As a special treat I've ordered a 3m Binzel torch to replace the 4m Parweld which I don't like because it's too long.