Common welding related questions we hear. Part 12
What’s the difference between spray arc (axial spray) and other methods of MIG welding? Can I spray with my 75/25 gas? If you are looking to really amp up your production with your MIG, you may want to consider using spray arc. Of course, that is dependent upon the size of your welder and the capability of it. Spray arc, more properly referred to as Axial spray, is a form of MIG welding that is greatly different in look and feel than traditional short circuit MIG.
To simply define Spray for the beginner, it is a form of MIG welding that uses high voltage and a higher wire speed to create a pinch effect on the wire before the wire ever comes into contact with the puddle. This action, when viewed in slow motion, shows tiny droplets of metal being pinched off the end of the wire, and transferring across the arc to the puddle. The arc does not extinguish. The sound will be quite, and the feeding will be smooth. The forward motion will be much quicker than in short circuit MIG.
The puddle will wet out and widen much faster as well. The weld when finished will be smooth and nearly ripple free. In short circuit, the wire actually stubs into the puddle, extinguishing the arc for a fraction of second before burning back and reigniting the arc. With Spray arc MIG, you will actually use a different gas as the voltage required to ionize the arc gap with 75/25 is much higher and will cause too much heat to be introduced. Usually 90/10 is used, or at least an 80/20 gas is used to spray. Other gas combinations may be used as well such as 98/2 Ar/O2.
Often times people confuse globular transfer with spray arc, but I globular transfer, the action is much more violent and irregular. Instead of consistent, tiny droplets of metal transferring, globular will transfer larger irregular drops of metal, with an occasional stubbing of the wire into the puddle. There are applications where globular welding may be performed but usually it is not presented as the ideal method of transfer unless spatter can be tolerated.