Components

Just like any machine, there are a lot of parts working together to generate what we are trying to accomplish. But before we open up the inside of our welding machine and are overwhelmed, let’s break down the GMAW setup into a few basic categories.

Our shielding gas components, the power source or “welder” capable of delivering a DC current at a Constant Voltage (CV), the wire feeder, and gun assembly. Sometimes, the wire feeder components are inside the power source/welder, and sometimes, they are an additional plug-in “remote” that sits on top of or near the welding machine (see Figure 10.5 below). Regardless of where the wire feed portion of the equipment is located, the parts and concept of how they work together are virtually the same.

You have already read about FCAW-G set up in a previous chapter; the machine set up for GMAW will be nearly identical. In fact, nearly all machines that can be set up for FCAW can also run GMAW with just a few changes to components like drive rollers and tips or nozzles. In the case of non-ferrous metals like aluminum, the gun liner would also need to be changed out for a plastic liner. Alternatively, a spool or push/pull gun may be used. Spool guns and push/pull guns, which have a different setup than the standard GMAW/FCAW-G machine were covered in Chapter 9: FCAW. A spool gun takes the wire reel and puts it at the gun handle near the welder. This is a much smaller wire reel, almost like what you may see on a fishing rod! (See Figure 9.8) This is used primarily for aluminum GMA welding to cut down on jamming. When the welding gun cable is longer than four feet, the aluminum wire can get caught up inside the liner and jam. This can be very problematic for fabrication companies that manufacture a lot of aluminum products like fishing boats. A spool gun gives the welder a longer gun cable and portability to do the work, while cutting down on jamming and allows the welder to move further from the machine than four feet.

Push-pull guns are similar in that they also help cut down on wire jamming, frequently used with non-ferrous metals, such as aluminum. But the wire reel stays in the machine. Instead there are a very small, second pair of drive rollers inside the handle of the gun. This helps ‘pull’ the wire through the gun cable, while the drive rollers in the machine help ‘push’ the wire through. See Figure 9.9

The photo above is a version of what you may encounter in a welding shop. The shielding gas system consists mainly of a cylinder of shielding gas, a flow meter to set the amount of gas that is withdrawn from the tank set in cubic feet per hour (CFH), and a gas line connecting the shielding gas from the flow meter to the welder.

• Shielding gas supply
• Regulator/flow meter
• Gas line

When the machine is opened (typically from a door on the side) the internal components are now displayed. It is not uncommon for a welder operator to have to access the inside of the machine on a regular basis. So it’s recommended to get familiar with what you are looking at. What does each piece do; why do you need it? As with any electrical piece of equipment, turn off the machine and unplug it, if possible, before opening the door and making any adjustments.

Inside the welding machine you will find something like the image in Figure 10.7.

• CV capable welding machine (components)
• drive assembly: the motor that provide the ability to move the mechanical parts
• wire spool: our consumable wire electrode wrapped around a spool.
• Inlet wire guide, intermediate wire guide and outlet wire guide: These are a series of cylindrical cone-like guides for the electrode wire to move through to keep it from jamming and stay on course. Typically made of plastic or brass. There might be all three listed, and some makes and models of machines may only have one or two wire guides.
• Drive rollers: The information contained in FCAW chapter regarding drive rollers reigns true regarding functionality and when selecting which drive rollers to use. The drive roller’s job is to move the wire along and help guide the electrode wire through the system. It’s important that the wire diameter and the wire size printed on the side of the drive rollers match. It cannot be too big, or too small. The groove type on the drive rollers matter as well. For hard wire processes like MIG for steel, a v-shaped groove is appropriate, but for softer wire such as aluminum, then a u-grooved set of drive rollers should be installed.
• pressure adjustment knob Increasing the distance or ‘loosening’ the knob decreases pressure applied to the electrode wire from the driver rollers. Whereas decreasing the distance or “tightening” the knob increases the pressure applied to the electrode wire from the drive rollers.
• gun securing knob
• GMAW Gun
• gun end
• gun trigger plug
• gun conduit cable
• gun liner
• goose neck
• Washer
• o-ring
• gas diffuser
• insulator
• contact tip
• nozzle
• Work clamp

Setting up the welding system

Setting up the machine can be a little confusing the first time. So far, we have already covered the machine’s inner workings and changeable parts. But say you run out of wire, need to change to a different size wire, or are converting over to GMAW after using the machine for FCAW. This section of the text does not take the place of the manufacturer’s guidelines and recommendations. It’s always best to go with what the manufacturer recommends for each of their machines, as there will be some subtle differences between products.

If you are converting from FCAW or a different wire size and type, start by removing the wire.

Holding on to the wire coming off the spool, clip the wire near the cylindrical guide. Do not let go of the wire connected to the spool. It will unravel the spool and cause you more struggle. Instead, wrap the end of the wire to the spool, either by weaving it through the spokes of a metal spool or using the holes on a plastic/wooden spool. Make sure it’s secure before letting the end of the wire go. Remove the whole spool from the machine.

Next, remove the reel from the machine.

You may need to release the clip holding the spool in place.

Next, remove any remaining wire that is left inside the MIG whip.

First release the pressure adjustment knob that is holding the drive rollers down.

Then straighten out the MIG whip. This will make it easier to pull wire through.

Unscrew the nozzle at the gun side, and pull off the tip. Using a pair of pliers or MIG welpers, grab ahold of the wire electrode sticking out of the MIG gun end, and pull it out.

If you are switching wire sizes, you will need another tip for the appropriate size. A different nozzle might also be necessary but not always.

Next, remove the drive rollers and replace them with the appropriate size in a V-groove type.

Now, it’s time to add wire to the machine.

Look at the inlet wire guide shown in Figure 10.13 vs Figure 10.10. Notice in Figure 10.13 that the inlet wire guide and drive assembly are horizontal, but in Figure 10.10, it is angled up. This matters when you are adding wire. Don’t let the wire bend when trying to make it to the inlet guide. It should flow in the path of least resistance. This means that in Figure 10.13, the wire will unspool from the bottom. In Figure 10.10, the wire should be placed so it unspools from the top.

When you unbox your new MIG wire, determine if you need the wire to feed from the bottom or the top. Then put the wire on the post that holds the wire in place.

Remove the end of the wire from the spool; it’s usually taped or wrapped against the side, and do not let it go. Feed the wire into the inlet guides and into the end of the gun end. Give a few pushes of wire into the gun end so you can securely let the wire go. Next, push the pressure securement knob back into place, effectively closing the drive rollers together.

Turn the machine back on.

Pull the trigger on the gun handle and watch the wire move through the drive system to make sure there are no snags. Once the wire comes out of the gun tip end, put the new MIG tip and the MIG nozzle on. The machine should be ready to weld!

Attributions

1. Figure 10.4: Gas metal arc welding equipment by Nicholas Malara, for WA Open ProfTech, © SBCTC, CC BY 4.0
2. Figure 10.5: Inside a GMAW ‘remote’ by Stephanie Oostman, for WA Open ProfTech, © SBCTC, CC BY 4.0
3. Figure 10.6: A gas cylinder and regulator by Stephanie Oostman, for WA Open ProfTech, © SBCTC, CC BY 4.0
4. Figure 10.7: Inside close up of a GMAW/FCAW-G wire feeder by Stephanie Oostman, for WA Open ProfTech, © SBCTC, CC BY 4.0
5. Figure 10.8: Secure the wire by Stephanie Oostman, for WA Open ProfTech, © SBCTC, CC BY 4.0
6. Figure 10.9: Removing the reel by Stephanie Oostman, for WA Open ProfTech, © SBCTC, CC BY 4.0
7. Figure 10.10: Pressure adjustment knob by Stephanie Oostman, for WA Open ProfTech, © SBCTC, CC BY 4.0
8. Figure 10.11: Clear the gun of wire by Stephanie Oostman, for WA Open ProfTech, © SBCTC, CC BY 4.0
9. Figure 10.12: Basic MIG (GMAW) gun components by Stephanie Oostman, for WA Open ProfTech, © SBCTC, CC BY 4.0
10. Figure 10.13: Driver rollers by Stephanie Oostman, for WA Open ProfTech, © SBCTC, CC BY 4.0