For er70,80,and 90 no purge. Works good( as long as the tube has no draft through it and it clean).
The place I am working at now wants me to tryout there stt Lincoln machine(similar to millers RMD.)
I have a really hard time believing that any stainless root beads can be put in without a back purge.
Anytime molten stainless is exposed to oxygen it will sugar.
I understand what miller and Lincoln say about there processes. It makes sense to me.
If anyone has been using either of these processes could they post a pic of one of these open root beads.
I still think these processes are snake oil.