Tips for Good Welding Penetration
The Voice: Hey, Kevin. What are you doing?
Kevin Caron: I had a really great question the other day from one of my YouTube subscribers. A new welder, he just got his first machine, asked, "How do I know when I'm getting penetration in my weld?" And I thought, good question, let?s do a video about that.
I have here four pieces of eighth-inch plate left over from a piece of metal sculpture I created here in the studio. I just pulled them out of the scrap bucket, cleaned them up a little, and chamfered the edges a bit so we can get a decent weld.
I'm going to make one weld with really low voltage, one weld right about the right voltage, and one weld really hot, to show you the difference between what welds look like; then we'll look on the back side and see what kind of penetration we're getting, noting the discoloration we get on the metal. That will show us how much heat is actually getting through.
Put your welding safety helmet on, we're going to make some sparks.
This one we're going to do at 14 volts. Yes, I know, that's pretty cold.
(welding) Now let's do the next one at say, 19 volts. (welding) Then let's do this last one at about, oh, what the heck - let's go to 24. (welding)
Can you hear the difference in the sound of that weld? Compare it to the first two. On the third one the weld sounded awful. What was going on there? The voltage is up so high that the wire feed is now too low. So the arc is melting the wire, just trying to travel back up in the gun. It's going to make an ugly weld.
Let's take a look. Remember, this is the cold weld: this was 14 volts. I've turned the metal so you can look at the weld right from the edge. See how high that is? Kind of humped up?
Now look at the next one. That was 19. Notice how it's kind of flat going across that section, like it's sunk down into the metal some. Because that's the same wire feed. I didn't change that at all.
Now come and look at this one, at 24. Can you see the difference in it between the other two? Now we'll look on the back side. See, here's the joint in the three different welds. This was 14 volts. You can see the discoloration, just a little bit to either side, where the metal got hot.
How about our weld at 19 volts? See how much bigger the discoloration is? A lot more heat. Let?s examine the metal that was welded at 24 volts. There's huge discoloration, due to lots of heat. But because the wire feed was set wrong, we didn't get a very good weld out of it.
Let's try something else, but first let me get my glasses.
Normally, if you were going to cut this weld open to test it, to see how good the penetration is, you would cut it across the weld then polish it. By the way, there's an acid, I think, that you put on it to etch the metal and then you can actually see the penetration into the metal itself. I don't have that here, so we won't be using it.
Here's the cold weld. As you can see, there's a whole bunch of the joint that's still bare. There's no weld in there at all. When you look at the 19-volt weld, you can actually see where some of the joint started to melt on this side. Remember, we welded it from the other side. If you examine the really hot weld, you can see it's starting to melt through on that side. With more amps and the wire feed set right, you're good.
So how do you know when you're welding if you're getting penetration? Well, I wish you guys could see what I see when I look through the lens.
When you're sitting there with your gun, trying to lay down a bead, and your weld is going on right where the big, bright spot is, you can look on either side as you're moving forward and you'll actually see your base metal getting pulled away, getting eaten away a little bit because it's being pulled down in your molten metal.
Pay attention. Look in that area and when you see it starting to actually pull the metal off, you'll see you are welding. You are melting your base metal. You're adding some filler metal. That's welding.
Hope that answers the question. See you later.
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