AC ripple on MIG / what makes a machine smooth?

[Masher Mfg]

I've been using a C K Systematics /Snap-on mig since 1986 ( bought the machine when it was 1 year old ) This is a straight transformer machine with multi tap for heat settings. The welds have usually been so so looking, mostly of varying width.

Got a hold of a broken Millermatic 130 ( 1986) this is a transformer machine with SCR output. Fixed a bridge rectifiyer on the SCR trigger board , cleaned it up and made it work.

The welds are much better than the CK, nice consistant ripples and constant width. The arc sounds rougher but the welds are great.

If a MIG has too much AC from a failed diode, not enough capacitors or a choke poorly sized, will the AC ripple cause the welds to look uneven?

[hankj]

You bet. GMAW is a DCEP process. The cleaner the DC, the better the weld bead profile, and the weld metallurgy, too! The elctronics in the newer machines produce very clean DC compared to machines made 20 years ago.

Just the opposite for me. I don't produce anything nearly as well as I did 20 years ago!

Hank

[Brand X]

The elctronics in the newer machines produce very clean DC compared to machines made 20 years ago.


I still take a MM-200 over a 251 on bead profile alone.
Same with the 250 migmaster over a fancy 260 mutimaster.