MIG welding is fast, it is easy to automate, and it suits thicker material well. The filler wire is fed continuously through the torch, so the process lays down a lot of metal in a short time. For brackets, flanges, thicker wall sections and general fabrication work, that makes it an efficient and entirely appropriate choice. Nobody should be talked out of MIG for those jobs.
The problem starts when the material gets thin. Exhaust tube is thin-wall by necessity - it is carrying gas, not pressure, and weight matters. The thinner the material, the narrower the window between a good weld and a hole. Because MIG adds filler and heat together, controlling that window depends on getting the wire feed speed, voltage, travel speed and technique all right at once. On thin-wall tube, a small change in any one of them can push the joint past the point where it burns through.
This is the part most people overlook, because it is invisible from the outside. MIG produces more spatter than TIG as a matter of course, and when you are welding a tube, some of that spatter ends up on the inside of the pipe. Inside an exhaust system, spatter is not a cosmetic issue. It disrupts the flow path, and a globule of weld metal sitting inside a high-temperature, high-velocity gas stream is a loose piece of material waiting to detach and travel downstream.
For performance exhaust work, the trade-off usually favours TIG. You give up speed and accept a higher labour cost per joint, and in exchange you get precise heat input, a clean internal surface, and a full-penetration weld you can inspect and trust. On a part that has to survive years of heat cycling and vibration, that is a reasonable exchange.
MIG is not the wrong process - it is the wrong process for some joints. Thicker material, structural brackets, mounting tabs and non-critical fabrication are all places where MIG is efficient and the result is perfectly sound. The useful question is not which process is better in the abstract, but which one the joint in front of you actually needs. If you are unsure how a particular part will be welded, ask us before you order and we will tell you which process it uses.
Our welded ranges are grouped by material: titanium welding parts, stainless steel welding and aluminum welding.
