While MIG welding might be one of the easiest types of welding, there are still some things that can go wrong, whether it be with the weld itself or something in the machine.

One of the problems that you might run into is the MIG wire snapping. The last thing you want is to be halfway through a weld and suddenly run out of wire, but it can happen. If your MIG wire snaps, you’ll need to clear out your torch and re-feed the wire through before you can start welding again.

But what causes the MIG wire to snap in the first place?

Causes of MIG Wire Snapping

Generally speaking, your MIG wire will end up snapping if it’s coming across a point of friction as it feeds through the torch and into the weld. There are a few things that can cause this friction that you’ll need to check:

• Is there too much tension on the wire?
• Is the torch liner clear with no blockage or build-up?
• Is the spool of wire in good condition?

As frustrating as having your MIG wire snap can be, the good news is that fixing any potential causes is relatively simple. 

How to Prevent Your MIG Wire From Snapping

The first (and usually the main) cause of wire snapping is having too much tension on the wire. This can come from the drive rollers or the spool lug, but either way, it’ll add extra strain to the wire.

It can be fixed or prevented by properly tensioning the rollers and the spool, which we’ll cover how to do correctly below. 

The second reason your wire could snap is from build-up or a blockage in the liner. Torch liners can become blocked if used for a long time, as metal shavings come off the wire while it travels through. Also, if the liner has a kink in it, that can become a point of friction, as the wire can’t pass through as easily as it should.  

If your liner has become blocked or kinked, it’s time for a fresh new liner.

The third reason is that the wire spool itself is the problem. If the wire you’re using has been left out in the open for any amount of time, it’s always a good idea to check it before using it. If it wasn’t sealed before it was put away, the extended exposure to air and moisture could have caused it to rust.

If your wire has started to rust, or none of the other two fixes have worked, grab a fresh wire spool.

How to Correctly Tension the Wire Drive Rollers

To get the correct tension on your drive rollers, start with a cold torch and feed the wire so that about 50mm hangs out the end. Then, decrease the tension on the drive rollers so that the wire slips (the rollers spin, but the wire doesn’t feed) when the torch trigger is pulled.

Turn the tension level a half-turn clockwise to increase your tension, gripping the exposed wire between your thumb and forefinger with light pressure. Make sure you’re wearing gloves to do this, as the wire can get hot.

Pull the trigger while holding the wire. If it slips, repeat the process.

Keep adding tension until you can’t stop the wire with your fingers, and it feeds smoothly without slipping.

How to Correctly Tension the Wire Spool

There are two nuts that are used to hold the wire spool in place. The first is the outer nut, known as the ‘spool retaining nut’. This is used to hold the spool in place and generally should be hand-tight. If this nut is too loose, the spool can end up falling off.

The second nut is the tensioning nut, which can be found inside the 5kg spool holder. This nut is what determines the amount of tension on the spool itself.

If it is too tight, the spool won’t spin, and the driver rollers will struggle to pull the wire from the spool. If it’s too loose, the wire spool will free spin and won’t break when it should, leaving you with a mess of tangled wire inside.

Your tensioner nut should be tight enough that the spool will stop spinning when the torch trigger is released but loose enough that it can still turn without resistance and not force the rollers to drag it off the spool. 

Incorrect tensioning on your drive rollers and spool is the main reason your MIG wire can snap while you’re welding. If you find your wire breaking, first things first, check your tensions. Then, if you’re still getting the same issue, try out some of the other fixes.