Wire burns right back when starting the weld

[berntd]

Hello

I am new here and I just bought a new BOC /Magmate 180P welder.
I do not have lots of experience with mig but I I do use TIG and oxy-acetylene - mostly for car restorations with thin sheet metal.

So, the first MIg I got, had burn back problems in that the wire always continued to advance about 10mm (1/2") after letting go of the button. The wire got really long after each stop. I returned that welder and got the BOC instead.

Now I have discovered that when I start the weld, after leaving it for say 30s, the stick out wire will burn off completely a few times. Thereafter, it will arc and weld quite nicely. I can start and stop, nice crackling sound and all- no problem but if I wait a while before restart, this burn off will happen again. SOmetimes, it burns back into the tip and then I need to unjam it.

Is this a normal effect and I am just using a bad technique or is this another bad welder? It sure ruins my spot welds on the .9mm sheet I am testing this on.

Please let me know as I can only return the machine up to Monday.

I am using .6mm wire with BOC Argonshield light gas (O2, CO2,argon mix)

Best regards
Bernt

 

[pedrobedro]

Is the wire live before the feed starts or staying live after the trigger is released ? If so it is a fault but not knowing anything about your "technique" it's impossible to say what is happening. Are you starting up with the wire in contact with the metal and how have you "unjammed" it ? I would be tempted to put a new tip on and check it's the right size before I did anything else.

 

[berntd]

Hello and thanks for the reply.

The problem is when starting not when stopping.
I have since added a new tip and the wire is moving smoothly.

I have tried both ways with wire touching the work and also without.

It happens in all event but as said, only at the beginning a few times.

It is like this:
Aim, ready to go.
Press trigger.
Wire advances, touches metal and the whole stick out piece becomes red hot in one go and melts away. Wire advances again and preocess repeats maybe 3-4 times and then, arc forms and welding commences normally.

This welder is an inverter type with "infinite" voltage, current (speed) and inductance control.

If it is just something I am doing wrong, any hints will be greatly appreciated

I am currenty trying to do plug welds but the sucess is limited because of this problem.

Regards
Bernt

 

[Robotstar5]

The first welder problem sounds like the burnback needed adjusting.

Second welder, have you got the tension on the feed rolls set right, is the wire spool sticking?. It sounds like the arc is starting but the wire is not feeding, either slipping in rolls or jamming in the liner. Release the rollers and pull the wire out, it should be smooth and need about .5 to 1 kg weight to pull.

 

[berntd]

Hello

Tension is such that I can't easily stop the wire.
Wire operation appears smooth and not sticking.

I have a feeling that this welder starts off with much higher current/voltage if left for a litle while and then settles back down at the correct value once it is going.
I don't know.

I gues I 'll give it a few more tries today and then possibly take it back on Monday.
My next try will be a Lincoln 180c . That is only $100 more than this machine and when i saw it after buying the BOC, I was impressed at the construction of the 2 roller drive feed mchanism.

Best regards
Bernt

 

[Robotstar5]

Would it be possible to demonstrate the problem at the shop where you bought it? I'm sure if they were a reputable supplier they would be happy to help as they want you as a repeat customer who would recommend them to others!

 

[michael1703]

have you got the tension on the feed rolls set right

Ive found this with 0.6 wire, it burns back unless you tighten the tensioner up, you need more tension on .6 than on .8 wire

try a bit more tension, try it with 0.8 wire too on a test piece and see how it runs

 

[Bristolbulldog]

Try upping the amps and feed rate. Does the wire retain most of its shape when it melts, or is it getting vapourised every time it touches?

 

[berntd]

Hello,

i think it vapourised the wire - sometimes.
It is all water under the bridge though because I returned that unit and bought a Lincoln welder instead.

I have not had this problem with the Lincoln since.

Best regards
Bernt

 

[rupertmja]

I have a 180P and have exactly the same problem but only when on the lowest settings. It's almost as if there just ain't enough power. Turn it up a tad and the problem goes away, but I want to weld think stuff, so my instinct is to turn the power down.

Hello,

i think it vapourised the wire - sometimes.
It is all water under the bridge though because I returned that unit and bought a Lincoln welder instead.

I have not had this problem with the Lincoln since.

Best regards
Bernt