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Up Topic Welding Industry / General Welding Discussion / Voltage check
- - By oldkid (*) Date 09-03-2002 23:58
Is there an easy way to check if the voltage setting the knob indicates is actually the voltage the machine is putting out? We have probably
40 Lincoln CV655's and they all run a bit different. The three that I run all seem to be way too "hot" for settings I have seen in reference manuals, publications etc. Example on a prior post a gentleman suggested using 28 volts at 200 wire speed. Our welders wont work at all on 28 volts until you put out about 300 inches per minute. I know the feeders are accurate as they just had them all calibrated. (I watched) If you try 28/200 all you get is a large hissing noise as the wire burns up into the tip. (New tip please) You guys are all I have for help so go ahead and laugh while you type if I am missing something simple.

By the way the wire is .045 and the shielding gas is 75%Argon / 25%CO2

As usual thanks,

Mark
Parent - - By Wildturkey (**) Date 09-04-2002 13:33
I guess the easiest way to check the voltage is with a volt meter on the leads while someone pulls the trigger. The wire speed can be obtained by holding the trigger for a length of time and multiplying it out to obtain IPM. As far as the voltage and wire speed you mentioned here is what I have from Lincoln. 24Ga-1/4" thick plate, 15-20 volts, WFS 100-200 IPM, Gas 25-35 CFH (Short Circuit Transfer). Many tables are listed this is just one of them. (Table 6 of the MIG/ MAG Welding Guide www.lincolnelectric.com) I hope this helps
Parent - By G.S.Crisi (****) Date 09-04-2002 20:19
I can't imagine any better way than that suggested by Wildturkey.
Giovanni S. Crisi
Parent - By Tim Buyle (**) Date 09-04-2002 13:47
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Parent - - By CHGuilford (****) Date 09-04-2002 20:27
When you say your wire feeders were recently calibrated, does that mean your volt meter on the feeder was calibrated too? or does it even have one (since some don't)? If you do have one and it was calibrated, then I would trust that meter, not the one on the power supply.

As the previous post said (I think it was Wildturkey?) the easiest way to check it is to put a voltmeter on it while someone runs a bead. One lead on the ground or wprk side and the other as close to the arc as possible on the electrode side of the circuit. Usually the terminal block on the wire feeder is sufficient.

I haven't used a CV655. Is there some type of control that you might have left "on" that gives a hot start? Probably not but I thought it was worth an ask. Otherwise, all you need to do is either turn down your voltage, or turn up your wire feed speed, or a little of both, enough to prevent burnback. And possibly the earlier post might have been using CO2 instead of an Argon / CO2 mix? Was the brand of wire he was running the same as yours?

The problem I run into when I try to give a volts/amps setting to someone is that everyone's technique is different. What I like to run may or may not work for everyone else. Even when following a WPS, some run hot and some run cold while still within parameters. So I guess, I wouldn't worry too much about sticking to 28/200. You tried it, it didn't work for you for whatever reason, so I would make adjustments (a little at a time) until it does work.

Hope this helps,
CHGuilford
Parent - By oldkid (*) Date 09-05-2002 01:40
No there is not a meter on the unit. I am just curious so I will get out my meter and check it out. Thanks so much to all of you for the help.

Mark
Parent - - By Niekie3 (***) Date 09-06-2002 18:15
Hi Mark

I think your problem here (unstable arc) has got to do with your gas - voltage combination. At 28V, you really want to be in spray transfer. The 25% CO2 will however not allow you to achieve this under normal operating conditions. I believe that you need to either get a gas with 20% CO2 or less, (85Ar/15CO2 is popular) or lower your volts and accept that you are welding in short cuircuit mode.

I am assuming that you are welding with bare wire (GMAW) and not flux core! (FCAW)

Regarding the measurement of the voltage, I always use an electronic multi-meter and connect the one pick-up to the terminal block of the wire feeder and the other pick-up against the work piece as close to the arc as practical.

Hope this helps

Regards
Niekie Jooste
Parent - - By oldkid (*) Date 09-07-2002 01:40
It would be a little hard to change the gas as I weld at a production plant with about 100 other welders. (LOL) But I wonder why they are running 25% CO2 if spray transfer could be better attained at another mixture? Anyway the 28 volts was a suggested voltage and I mentioned it as showing why I thought my volts may be off. Thanks a bunch for your input and I'm getting headed in the right direction.

Mark
Parent - - By Niekie3 (***) Date 09-07-2002 16:56
It may be that they actually want you to be welding in dip transfer. Remember that you can not weld out of position with spray transfer.

Regards
Niekie
Parent - - By jffluxcore (**) Date 09-07-2002 19:02
A tech at MK Proucts said that AL. could be in Spray in overhead position, Does tech at MK fib? Thanks Jim
Parent - By welder_guy2001 (***) Date 09-08-2002 06:36
i'm not sure, but from what i've seen/heard while MIG welding aluminum, it sounds like spray transfer instead of short circuit...even when the machine is set on a cold setting. maybe i'm wrong and it's just a very high frequency of short circuiting that makes it sound more like a spray.
Parent - By Niekie3 (***) Date 09-08-2002 22:08
I had a quick look at some of my Al welding literature, and indeed it is recommended that Al be welded in spray transfer as far as possible, as dip transfer results in lack of fusion defects and excessive weld spatter. The voltage settings are also mostly on the high side, for all positions (22 - 30V) which suggests that spray transfer is maintained.

It appears that the fast freezing behaviour of Al allows one to use spray transfer for all positions. The obvious problem is where the material is very thin and can not absorb the high heat inputs without burn-through. In this case, pulsed spray is the answer.

Having said all this, I believe that "oldkid" is welding steel and not Al. In the case of steel, it is not possible to deposit a decent weld in spray transfer in the overhead position.

Regards
Niekie Jooste
Up Topic Welding Industry / General Welding Discussion / Voltage check

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