Chris_Hamilton
Trying to be the best me, I can be
by me they recommend the tri mix. I have no luck with penetration with solid wire and tri mix so maybe they are wrong. I have tried 023 030 and it just sits on top of the panel. The .035 flux core works best. If I try to add tri mix to that the penetration goes away.
I know if you are doing aluminum you need pure argon, but I can definitely tell you I get no penetration with the tri mix. Just if that makes any sense to anyone.
Like Metalman said trimix (90% Helium, 7.5% Argon, 2.5% Co2- looking at the bottle of it I have) is used for Mig welding stainless. Used on anything else it is not the correct choice. Using it on steel it's going to weld very strangely, similar to what you said. For Mig welding mild steel 75% Argon 25% Co2 is what should be used. 85% Argon 15% Co2 can also be used on sheet. The lower amount of Co2 helps with less penetration but it is hard to find and really unnecessary as 75/25 works well with even the really thin gauges.(22-24ga)
100% Co2 will be a nightmare to use with thin gauge sheet because penetration achieved with Co2 is much greater than 75/25. 100%Co2 is best left to heavier material. The greater the amount of Co2 the amount of penetration will increase.