Mig welding iron/steel vs aluminium and cu

[paulo1974]

Hello
Today I came across a photo of a mig welder transformer based with two plugs for the clamp cable. One is for steel and the other is for cu/ aluminium (si-al) is there a difference between the machine for welding aluminium besides the rollers and guide? I know that some welders on MMA have 2 plugs on on lower voltage like 50 v and another for a higher voltage like 70v (basic eletrode). Anyone has any ideas?

 

[Munkul]

Hello
Today I came across a photo of a mig welder transformer based with two plugs for the clamp cable. One is for steel and the other is for cu/ aluminium (si-al) is there a difference between the machine for welding aluminium besides the rollers and guide? I know that some welders on MMA have 2 plugs on on lower voltage like 50 v and another for a higher voltage like 70v (basic eletrode). Anyone has any ideas?

It sounds like an inductance setting. Quite common for older, good quality mig sets. Usually use higher inductance for short-arc mig and lower inductance for spray arc.
Mig brazing (al-si) works pretty well on spray arc so maybe that's why it's labelled like that.

 

[Robotstar5]

It sounds like an inductance setting. Quite common for older, good quality mig sets. Usually use higher inductance for short-arc mig and lower inductance for spray arc.
Mig brazing (al-si) works pretty well on spray arc so maybe that's why it's labelled like that.

3 inductance options on this Kemppi set we had at work.

 

[Mark 2]

Aluminium and copper would be ac surely.

 

[E T]

Aluminium and copper would be ac surely.

Not with MIG.
The AC bit is only for aluminium TIG. You need the + side of the wave form to break the oxide layer, and the minus side to keep the tungsten from burning up simply said.
Copper can be welded on DC no problem i believe. Never done it tough.