Shielded Metal Arc Welding (SMAW or stick welding) was one of the first arc welding processes invented. It dates back to 1890 and it is an excellent option for beginners, as the equipment to get started is simple and economical. But its simplicity doesn’t mean it’s not worth learning – it’s one of the most common welding processes used in industry today.
SMAW is a valuable skill whether you’ve been welding for a while or are just getting started. This guide to shielded metal arc welding will show you everything you need to know to get started.
What Is Shielded Metal Arc Welding?
Shielded metal arc welding is an electric arc welding process.
It uses fixed length, consumable electrodes that come covered with flux. When this flux burns at the arc, it forms a gas shield protecting the molten weld metal from the elements. Other arc processes like MIG and TIG also protect the arc -- with supplied gas rather than created gas.
What Does Metal Arc Welding Mean?
Metal arc welding means the base and filler metals melt through an electric arc. Shielded means the arc has protection from oxygen and other gases to prevent impurities from entering the weld.
Therefore, SMAW means welding metal with electricity while protecting it from impurities.
The Science Behind Shielded Metal Arc Welding
SMAW uses electricity to pass energy through a weld joint with enough heat to melt metal. As the consumable electrode gets fed into the joint, it deposits weld metal and joins the two base materials together.
How Does It Work?
SMAW works by holding an electrode at one end with an electrode holder, and briefly touching the other end to the workpiece. This brief contact creates an electrical circuit that starts the welding arc. Unlike MIG welding, you have to manually feed the electrode into the joint to maintain the arc, requiring more hand-eye coordination.
SMAW electrodes come coated with a flux that burns with the filler metal. As the flux burns, it creates a gaseous shield around the weld pool that protects it from the atmosphere. Since you don’t need to worry about supplied shielding gas, SMAW is excellent for windy conditions.
What Supplies Do You Need to Shielded Metal Arc Weld?
Below you’ll find everything you need to get started with shielded metal arc welding.
Arc Welding Power Source (Welding Machine)
You’ll need a constant current welding machine to do shielded metal arc welding. These are different from machines designed for MIG welding, so make sure you get a machine capable of SMAW or stick welding.
Before buying a SMAW machine, ensure its capabilities meet the size and type of electrodes you’ll use. Keep in mind the following when evaluating SMAW welding machines.
- Polarity: Polarity may be direct current electrode positive (DCEP) or direct current electrode negative (DCEN).
- Amperage rating
- Duty cycle: This expresses the percentage of time in minutes that the machine can operate at a certain current continuously out of 10 minutes (e.g., 40% duty cycle means that the machine can operate at a certain current for four minutes continuously).
- Advanced features
Welding Hood or Visor
You’ll also need a welding hood to protect your eyes and face from harmful UV rays of electric arcs.
Consider getting an auto-darkening welding hood since SMAW is more challenging to start an arc. This way, you’ll see the end of the electrode and have more success as you start the arc.
Remember that arc welding is only possible with a complete electrical circuit. Leads, or welding cables, carry electrical current to and from your workpiece and electrodes. There are two types of leads: The power cables that connect the electrode holder to the welding machine and the return lead that connects the ground clamp to the welding machine.
As with power source and electrode selection, you’ll need to buy large enough cables for your application.
A ground clamp attaches to return leads and clamps onto your workpiece. It's vital to the electric circuit, and you replace a ground clamp as soon as it starts to wear.
Ground clamps also have specific amperage ratings, so make sure you get one rated for your intended use.
The electrode holder connects to your other lead and clamps the welding electrode’s bare end. Just like ground clamps, good electrical contact is critical for welding success. Some electrode holders come with removable clamp plates so you can replace them when worn rather than the entire holder.
Also, like ground clamps, electrode holders are rated for certain amperages, so get one that will suit your needs.
Welding electrodes are the filler materials that melt at the arc to form the weld. There is an entire spectrum of welding rod choices from general-purpose mild steel electrodes to highly specialized alloy electrodes.
The SMAW process leaves a layer of hard slag on the weld that you’ll need to remove. A chipping hammer can chip away this hard coating so you can see the underlying weld.
More important than anything else on this list is your welding safety equipment. See below for some essential items to protect yourself.
You might think your welding hood is all you need to protect your eyes in a welding shop, but that isn’t true. It’s easy to forget your hood is up when you’re chipping hot slag or just doing a quick grind on a piece of steel. It’s also easy for sparks and debris to enter your eyes when unprotected.
Long-Sleeved Shirts and Pants
With hot metal on the welding table and sparks flying every which way, there’s a high likelihood your arms or legs will contact something hot enough to burn you. Your best defense against welding-related burns is proper clothing. Aside from leather, you should stick to 100% cotton long-sleeved shirts and pants.
A good pair of leather work boots are essential when welding. Gravity brings all things hot down to your feet, and you don’t want a piece of hot slag to land on the top of your foot when you’re wearing flip flops. Get steel-toe boots if you’re working with heavier workpieces or tools.
As you weld with SMAW, your hands will slowly get closer to the weld as you feed the rod into the joint. You’ll want leather welding gloves to protect your hands and keep them comfortable as they move closer to the arc.
All arc welding processes emit the same UV rays as the sun, but are a lot closer in proximity. It’s common to get sunburn from welding, so use sunscreen on any exposed skin you cannot cover with clothing.
Perhaps the most important item on this list is the fire extinguisher. Neglecting the rest of the safety gear can cause you harm, but ignoring the fire extinguisher can harm others. So make sure you have a fire extinguisher nearby whenever you’re welding.
The body of this machine is connected through earthing cable to a copper bar inserted into the ground beside the machine, to continuously remove the stray electrical charges coming to the welding machine body during welding to protect the welder from any electrical shock.
Getting Started With Shielded Metal Arc Welding
Here’s a quick start guide to making your first welds with SMAW.
Prepare Your Tools and Workspace
First up, make sure your work area is clean and free of flammable materials.
Gather your tools and equipment and organize them so as not to bump into them with your hood down.
It’s good practice to let others know you’re going to be welding so they can stay clear of your work area unless they’re also wearing safety gear.
Select Your Electrode
Once you know the type of steel you’re welding, you can choose a suitable electrode. You’ll need to match your electrode to the base metal and your machine's polarity capabilities.
All electrodes come with an AWS classification that tells you everything you need to know about welding with the electrode.
According to AWS A5.1 for carbon steel electrodes, the fourth digit tells you which polarity the welding rods work with.
Hook Up Your Leads
Now that you know which welding rods and polarity you’ll use, it’s time to hook up your leads.
Based on the AWS chart above, you’ll need to hook your electrode lead (the one connected to the electrode holder):
- To the positive terminal of your welding machine if using DC+
- To the negative terminal of your welding machine if using DC-
- To either terminal of your welding machine if using AC
Then hook your ground lead up to the other terminal.
Set Your Amperage
Next, turn on your machine and select an appropriate amperage for the size and type of electrodes you are using.
Your welding rod supplier should be able to give you a spec sheet that states typical amps for the electrodes you purchase. If not, a good rule of thumb for 7018 electrodes is to convert the decimal equivalent of the electrode size to amps.
For example, a ⅛-inch 7018 welding electrode would be 0.125” in decimal form, so you would use 125 amps to start. You can fine-tune your amperage based on how the weld appears.
All that’s left now is to weld. Flip down your hood and gently slide the electrode tip across the base metal near the start of the joint to start the arc.
Be careful not to keep the electrode too tight to the base metal as the arc initializes, or you might “stick” the electrode to the workpiece.
Once the arc stabilizes, feed the electrode into the joint while simultaneously moving the electrode end along the weld path. It will take some practice, but try to feed the electrode at a consistent rate for best results.
Although other processes are beginning to replace SMAW for some applications, it’s still used heavily in certain industries.
One of SMAW’s most significant features is simplicity. You pick a rod, set the amperage, and you’re ready to weld. From fencing to equipment repair, the welding jobs on a farm are usually basic, so SMAW often meets these needs.
Mining equipment often breaks or wears, leading to remote repairs and build-up operations. SMAW works well in these situations since it’s highly portable, and there are SMAW electrodes available specifically for these applications.
Although many steel structure parts get fabricated in the shop, field installs still need portable welding. Again, SMAW shines here since you can use it in windy conditions and access hard-to-reach areas.
Some mechanical industries still use SMAW extensively. Pipeline projects still favor SMAW’s portability and consistency, and some oil companies prefer to stick with tried-and-true methods.
SMAW Pros and Cons
There’s only one setting to think about, and you can get started with minimal investment. You don’t need to buy welding gas or worry about the hazards of storing compressed gas cylinders.
Since the equipment is quite simple, it’s easier to take from job site to job site. Also, due to the nature of the self-shielding electrodes, SMAW is well suited to welding outdoors regardless of wind conditions.
Reach Limited Access
SMAW electrodes are usually at least 12 inches long to start and don’t have a bulky MIG gun to feed them. This lets you access hard-to-reach areas you might not otherwise be able to weld.
Not Suitable for Welding Thin Metals
There are techniques to weld thinner metals with SMAW, but its limitations do cap out eventually. So when looking to weld sheet metal, it's best to switch to a process like MIG or TIG.
Requires Practiced Welders
Although the process is simple, manually feeding the electrode while welding can be challenging for some. Therefore, it will take more practice to produce sound welds than if you had been using another process like MIG.
There are many SMAW welding rod choices for more common metals but not so much for some of the exotic metals. When welding thin metals, you may have to switch to MIG or TIG when welding specialty metals.
Shielded Metal Arc Welding FAQ
What Is the Difference Between SMAW and MIG Welding?
SMAW and MIG are both electric arc welding processes but differ in how the electrode gets fed into the weld pool. For example, SMAW electrodes get manually fed, whereas MIG electrodes get fed automatically.
MIG also uses supplied shielding gas, whereas SMAW creates its own as it burns the flux on the electrode.
MIG uses constant current and constant volt power sources but SMAW works only by constant current power sources.
What Is the Difference Between SMAW and TIG Welding?
Like MIG, the TIG process supplies shielding gas rather than creating its own like SMAW.
TIG also differs because it uses a nonconsumable tungsten electrode that doesn’t feed into the joint as you weld. Instead, SMAW uses consumable electrodes that double as filler metal.
How Do You Know Which Polarity to Use?
If your electrode works with multiple polarities, you’ll need to choose the one that gives your desired effects.
Do You Push or Pull When Welding?
Due to the slag that stick welds produce, it’s essential to use a pull (or drag) technique to prevent slag inclusions in your weld. Remember: If it’s slag, then you drag.
Next Steps: What to Do After Learning SMAW
Now you know how to weld with SMAW. When you’re ready, here are some suggestions to take your skills to the next level.