Because its not deemed as high enough quality.
Also its not great for positional pipe welding, its easy to get defects on start/stops.
Be interesting to see if this will change: current building practice in the States is to weld the main girders of skyscrapers together using enormous gasless mig sets (as in the Modern Marvels video -- 50 man hours welding, IIRC, for one joint in one spar). Now, at a pinch, I'd choose a skyscraper collapse over a nuclear catastrophe, but not by that much. And the skyscraper will be in operation for much longer than the nuclear plant!
I have personally never used it...........although I do hear its very good.
I haven't used it myself either Matt, apparently a good mig hand will pick up the process with proper training fairly quickly and easily!
Many of the poor attributes associated with current mig as we no it is eliminated. Even beats tig hands down in certain applications. Tomorrow I am going to try to organise a practical session in the near future. If this pans out, I'll be more able to make a comparison with MIG against STT.
Cheers.........
All of our Inverter based machines have got DSP's inside, they all now operate on a kind of Can bus system(Think Fly by wire technology), rather than 0-10v Analogue signals. Gives much faster reaction time in the arc, totally repeatable outputs from the welding machine (Imagine the comparison in sound quality from a Digital CD/Mp3 compared to a Analogue Vynl record), synergic lines can be added/removed/modified in seconds via a computer and there's much less components inside. They are even self diagnosing, and will tell the service engineer which PC Board has failed. Certainly moved on a lot in the last 10 years or so
Ohhh can bus hey, you wouldn't believe the trouble iv know that cause, not on welders mind......