Mig welding wire part 1

With so many different brands of wire on the market these days, It becomes hard to make the right selection of a quality weld wire.

Mig welding wire is all the same...isn't it?

Well in actual fact there are many things that separate one brand from another.

Things like;

1. Raw materials used

2. Copper coatings

3. Diameter tolerance

4. Cast

5. Helix

6. Consistency

These are all things that need to be looked at, in order to make the correct decision on which wire to run with.

What's more is:

1. Does it need to be of any standard?

2. Do you need any approvals?

3. Does your engineering department need a copy of the consumable certificate?

4. Does your engineering department need a copy of the mill certificate?

So having just mentioned all this, can you start to see that wire isn't just wire?

And that there are many things that determine the quality?

Okay, so what do you mean by all of this?

Raw materials used

The quality starts from the very beginning in the manufacturing process. What are the raw materials that the manufacturers are using? Are they using new raw materials or are they using scrap steel?

Some welding wires will actually be made from recycled scrap steel, i.e. old ships and cars are cut up and melted down. Then when the scrap metal is refined not all of the impurities are removed. This leaves you with a wire of a much lower quality, which in turn results in a whole range of issues such as, spatter, burn backs, porosity and feed issues.

This is why you need to ask for a mill certificate. This will show the quality of the raw material that is used straight from the start of the wire manufacturing process.

Copper coatings

The copper coating is the copper coating which is on the outside of the mig wire. It is there to serve a variety of functions, not just to look pretty.

Why is it important to have a copper coating?

1. Copper is an excellent conductor of electricity. It provides good current pickup at the contact tip during welding.

2. As copper is softer than the wire itself. The copper coating acts as a soft abrasive action whilst travelling through the contact tip, as opposed to having the harder wire wear the contact tip out.

3. The copper coating also serves as a protective layer. If there was no copper coating on the wire, corrosion of the wire surface would eventuate much quicker, rendering it unusable.

What type of testing of copper coatings does your wire manufacturer perform to ensure consistent even copper coating on their welding wires?

For example, look at these pictures below of a Copper Adhesion Test

Notice that this is zoomed in with 500 times magnification. It shows acceptable and not acceptable copper coatings.

Does the manufacturer of your MIG welding wire regularly perform these quality assurance tests?

Wire diameter tolerance

What size wire do you run? 0.9mm, 1.0mm, 1.2mm?

There's not much difference between wire sizes. I mean come on what's 0.1mm between wires? That's like nothing!

What are the tolerances on the wire that you use? What are the manufacturing tolerances? +- 0.1mm?Is the wire just oversize, under size or both? And what effect does this have?

Wire feedability is critical in welding. You don't want the wire to stop start, stop start, shudder in the liner, slip at the rollers, burn back and so on. One area to look at is the manufactures wire diameter tolerance and the wire consistency. You want a wire that has the tightest possible tolerance and the best consistency.

Now using the same diagram, I'll put in the feed rollers.

Now as you can see. The good wire with the tighter tolerance and the best consistency is always in contact with the feed rollers. There is no possible way of the wire slipping in the feed rollers, as maximum contact is achieved with every revolution of the feed rollers.

But on bad wire you can clearly see the difference.

The wire diameter is all over the place, oversized undersized and is not consistent. What this means the feed rollers at one point will slip because the wire is under size.

Then when the wire is oversize the wire will bind up into the feed rollers. This binding in the feed rollers will add more pressure to the wire, which will cause the copper coating to flake and come off. The bits of copper will then in turn go down the liner of the welding torch and cause even more problems.

So you can see why the wire tolerance and consistency is absolutely critical for reliability, less down time and less frequent replacement of consumables.

Here is a good place to get some ER70S-6 mild steel mig welding wire.