A question we get frequently is “Why shouldn’t I use flux core MIG welding to install the patch panels?” and so we made a very down and dirty video to show the differences in weld methods you would typically see when butt welding sheet metal. The quick answer is that flux core MIG can be used to join metal, but because weld puddle control is pretty critical to successfully welding sheet metal (in this case 20 gauge), we strongly urge customers to use gas shielded MIG – it will provide a better outcome and certainly reduce frustration.
As you can see in the video, flux core MIG produces quite a bit of weld slag and BB's that must be cleaned up after the fact. This means the grinder will be used more for metal finishing and that poses additional risk to the thin metal. Also, because of the nature of flux, it can be very tricky to initiate follow on welds when trying to stitch the joint together. In fact a common welding technique is to “trigger” the gun and stack a number of tacks to weld the joint, cooling every 5-10 tacks to minimize warping – with flux core this technique isn’t feasible due to the slag. Using a gas shield greatly reduces the spatter (and sparks – which can affect other areas of your work) and allows for a better control of your weld pool, resulting in a more consistent weld joint – with less clean up. Indeed gas shielded MIG setups are more costly (you add a regulator, hose and gas bottle as well as the cost of the Argon/CO2 gas), but in our view it is well worth it both in resulting work quality as well as reduced frustration with panel replacement which already has its share of frustrations built into it! So, beg, borrow, rent or steal a gas shielded system – you’ll be happy you did.
You will also note that TIG is demonstrated in the video. This is really just to show all the options available. If you have a TIG system, then that certainly would be preferred over the other process because the degree of weld penetration and control of metal filler is so high. That said, it’s the most costly process and certainly not mandatory for welding patch panels. So, keep in mind that welding thin gauge sheet metal is tricky with any welding process (note the video is showing pieces bench-welded and backed which makes thin gauge butt welding look a whole lot easier!), why not up your chances of success with gas shielded MIG?