MMA welding uses a high intensity electric arc to weld the workpiece to the electrode. It is also called stick-electrode, arc welding or SMAW.
The MMA process
If you are completing a weld using an MMA welder, the electrode must be fed through manually. This is the filler metal and will conduct the current.
The electrode will have a flux coating which is designed to melt as it heats up. The electrode will create molten metal while the flux will create an arc to form a shielding gas. This arc shields the electrode and the workpiece so that they form a weld pool. The mounted flux will create slag on the weld which will need to be cleaned when it is completed.
As with all welds, you must ensure that everything is set up correctly. For MMA welding there are several things you must prepare before you begin.
- While MMA can be very forgiving, you will still need to prepare your workpiece properly. Always wipe it down so that it is free from dust or grease and remove as much rust as possible.
- Make sure you have chosen the correct travel speed for the electrode.
- You will also need to have the correct size of electrode. Most welding jobs will handle electrodes of 2.4 mm, 3.2 mm and 4 mm. If you are welding a smaller job, you will obviously need a smaller diameter such as 1.6 mm or 2 mm.
- The angle of the electrode must also be correct and this will also depend on the type of weld you are completing. As a rough guide, if you are doing stick welding or MMA welding you should hold the gun at an angle of 20° to 30°, but if you’re carrying out a fillet or tee weld, you should hold the wire and an angle of 45°.
- With MMA welding the length of the arc should usually be equivalent to 0.5-1.00 times the diameter of the electrode.
- MMA welding will need a high current of between 50 and 350 Amps, with a low voltage of 10-50.
It’s also important to select the right electrode. The most commonly used are cellulosic, rutile and basic.
- Basic: This mainly consists of calcium compounds, and will create a shielding gas of carbon dioxide.
- Rutile: The constituent of this one is titania, and it creates a carbon dioxide shielding gas.
- Cellulosic: The main constituent in this electrode is Cellulose, and it creates a shielding gas which is a mix of hydrogen and carbon dioxide.
Uses of MMA welding
As with all welding methods, MMA welding can be used on most joints. It handles cast iron, stainless steel, steels and non-ferrous items very well and is ideal for moderate and high resistance carbon steels.
- MMA welding is relatively inexpensive and has low maintenance costs
- Heavier metals can be welded with the same output, as they can generate more power.
- Many MMA welders are compact, so they are portable. This makes them ideal for site and field work, and as they do not need a shielding gas, they are not usually affected by weather.
- They handle rusty or dirty materials very well.
- MMA welding is easy to learn and easy to use.
- Works with most metals, including iron, steel, copper alloys, nickel and aluminum
- Working with thinner materials can be tricky as it is hard to avoid ‘blow through’
- The process can be slower than others, as the electrodes do need to be replaced.
- Slag is produced with the weld, and this will need to be chipped off.
Frequently Asked Questions:
What do you need for MMA welding?
- A reliable power supply which has both AC and DC. While all AC electrodes can be used with DC, not all DC electrodes can be used with AC.
- You will need a ground cable and a welding cable, which should have an electrode holder. Make sure this will hold the electrode securely.
- As with all welding, there is a risk of being burned by spatter so always wear a face shield and gloves. Leather or safety gloves are recommended, as spatter can burn through cheaper ones. Aprons can also help protect your body from burns. When removing spatter, wear your face shield or goggles to protect your eyes.
- Always consider ventilation when welding. If working outside, then the fumes will likely disappear on their own, but indoors make sure there is good ventilation and that the fumes are blowing away from you where possible.
- You will also need a wire brush and chipping hammer to clean the joint before welding and remove the slag.
Which metals are the electrodes available in?
MMA electrodes are available in a variety of metals to make sure you create a strong joint.
You will be able to get electrodes in
- Cast iron
- High carbon steel
- Mild steel
- Special alloys.
Can I use my MMA welder outside?
One of the big advantages of MMA welding, is that is can be used outdoors. As you don’t need to create a shielding gas, MMA welders are less susceptible to the weather so they can be used almost anywhere.
Is MMA suitable for beginners?
Beginners will be able to learn MMA welding, but it’s not the easiest process if you’ve not welded before. Other forms of welding, such as MIG welding, have an automatic electrode feeder which is easier for beginners.
MMA welding is ideal if you work outside or on site. Most MMA welders are portable, and as the process creates its own arc, it is easier to work in all weather conditions.
Manually feeding the electrode isn’t easy, and it will take practice to get the right speed and calculate the correct settings. For this reason, it’s not a good choice for beginners, but that doesn’t mean you should avoid MMA if you’re new to welding. Just take the time to practice everything before you get started.
Due to the amount of slag created, it can be time consuming, but as it is a very forgiving process, it does make it easier to work with all metals.