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Welding of thin metals with electrodes, pull-off welding - this is the easiest way to weld such a metal. But beginners also have problems here. These are frequent metal burn-throughs.
In this short article, we'll show you the root cause of this phenomenon and give you some simple advice on how to keep burn-through on thin metal in tear-off welding to a minimum.
What do we most often weld for our household needs? These are all sorts of structures from a profile pipe. It is a relatively inexpensive and durable material. But it has a small thickness. For the house, most often they take a pipe with a thickness of 1.5-2 mm.
Let's review the basic tips for non-burn welding of such pipes, and then show the most significant problem and its solution.
- We cook with rutile coated electrodes, such electrodes are easy to reignite to cook point by point.
- We try to select the diameter of the electrode according to the thickness of the metal to be welded, we do not need to cook everything in three.
- We put straight polarity, we connect this holder with an electrode to the minus of the welding inverter, so there is less chance of burning.
- The gaps before welding in the joint should be as small as possible; with large gaps, the edges of the pipe melt very easily and quickly.
If you follow the recommendations above, then we are already halfway to the torch-free pull-off welding.
And now I will show, in my opinion, the most basic reason for burn-throughs. When you work constantly, you no longer notice the details that make up a good end result. But when you carefully decompose your actions into separate moments, then everything becomes clear.
Re-ignition of the electrode is where the most burns occur for beginners. That is, how to reignite, where in the seam.
We start to cook the seam. We light the electrode, a weld pool begins to appear, the metal under the electrode melts, additional metal flows from the electrode into the bath. This bath, as it were, spreads in all directions, here we tear off the electrode.
Through the mask, after tearing off, we see the glow of the weld pool - it is, as it were, round, slightly oval in shape. At the moment of separation, we photograph with the eye its contours, the boundaries of the bath.
In a split second, the bath begins to cool and fade. At this point, we need to point the electrode back to the metal to make the next point. And here you need to do it right.
Re-ignition should be done exactly within the boundaries of the cooling point. That is, the coating of the electrode should not go beyond this border, let them at the moment of ignition become on the same line-border and coating, you can even go a little bit inside the cooling bath, by a millimeter, not more.
Why is that?
If you reignite beyond the boundary of the cooling bath, then there is also a very hot thin metal, plus in any case there will be a gap between the edges. Part of the arc hits this gap and instantly melts the edges, that's the burn-through.
And if we reignite within the boundaries of the previous bath, then the thickness of the metal is already more serious here, we have already welded a point onto the base metal. Plus there is no gap between the edges. The arc instantly melts the bath, and it spreads a little further. Here we tear off the electrode and everything is repeated again.
And so, point by point, the weld seam fills the gap, connects the edges of the metals being welded. And it is less likely to burn through with this welding method than re-igniting at random a little further, a little closer to the previous welded point.
I have already shown this technique before, this is how beautiful tight seams are obtained. Regular readers of the channel will probably remember this. It's just that the right thought has come right now, and with such a welding technique, we also reduce the likelihood of burn-throughs. So it turns out two-in-one, a beautiful seam and there will be no burn-throughs.