Stick welding is commonly referred to as arc or MMA (Manual Metal Arc) welding. The name arises from the fact that the welding arc is formed between the flux-coated stick electrode and the welded metals. Both the workpiece and the electrode melt to form a weld joint. This means that the operator must continually replace the electrode as it is consumed.
And just like any other welding process, welding polarity plays a critical role in the success or failure of your welding activities. The welding polarity is simply the direction in which the welding current flows when welding. Different welding processes are designed to run on different polarities. If you choose the wrong polarity for your specific process, the welding results will be substandard.
Polarity for stick welding
As we’ve mentioned, welding polarity is an important variable for welding, and it has a significant impact on both the welding penetration and the weld bead profile of any given weld. Some welding methods operate best on a positive (+) polarity, while others are better run on a negative (-) polarity. So what’s the best polarity for stick welding?
i. DCEP/DC+/Reverse Polarity
DCEP or simply DC+ is the standard current for stick welding. When welding on DC+, the operator is required to connect the electrode to the positive terminal and the workpiece (ground lead) to the negative terminal. This way more heat is directed to the workpiece, resulting in deep weld penetration.
Most stick welders are designed to run on reverse polarity output. This is because it provides a more stable arc, and it is not characterized by frequent arc outages. In addition, reverse polarity is best suited for welding thick sheets of metals since the arc generates more heat.
In general, thick metal plates are designated to have a high melting point, and this is where a DCEP polarity comes in handy.
Advantages of DCEP
- Cleaner arc
- It is a perfect all-around choice
- Deeper weld penetration
- Minimal defects
- Suitable for thick materials
- It is mostly limited to thick materials, although you can still weld some thin materials
ii. DCEN/DC-/Straight Polarity
DCEN or simply DC- is the complete opposite of DCEP polarity. When running on straight polarity, the electrode hooks to the negative terminal, while the work lead is attached to the positive terminal. Typically, this type of connection directs more heat to the electrode which in turn results in a speedy deposition rate.
However, DCEN polarity does not result in deep weld penetration, making it ideal for applications that require light penetration. In addition, DCEN polarity in stick welding is mainly associated with incomplete fusion since less heat generated at the base metal. This makes it less popular in stick welding, but it is not uncommon to find stick welders specially designed to run on a DCEN output.
Advantages of DCEN
- Offers faster melt-off of the stick electrode, thereby resulting in an increased deposition rate
- Easy to strike an arc
- The arc is more stable than when running on an AC output
- Reduced spatter
- Low weld penetration
- It is limited to thin plates of metal
- High chances of incomplete fusion
- Electrode burns out faster
iii. AC (Alternating Current) Polarity
Most stick welders are designated to run on either a DCEP or DCEN polarity, but a few of them have the capability of running on an AC current. Unlike DC, where the current flows in one direction, the alternating current, just as the name implies, keeps switching between the positive and negative in a matter of microseconds.
In half the cycle, the work lead current will run on a positive polarity, and the earth lead will be negative. The second half of the cycle will have the work lead running on a negative polarity while the earth lead will be positive.
Although AC is not preferred for stick welding, older stick and entry-level welders may only have an AC power output leaving you with no option but to use an AC polarity. However, modern models rarely have such limitations, with some giving you the option of using all three current types.
Advantages of AC current
- Ideal for welding training
- Provide attributes of both straight and reverse polarities since both will be present in one cycle
- Best suited for different plate thicknesses
- Less stable than DC
- Associated with low-cost, entry-level welding machines
What polarity for stick welding 7018?
The 7018 is probably the most used electrode type for stick welding, so it is not uncommon to come across this question in various welding forums. The 7018 electrode is a multi-purpose welding rod that is mainly used to weld carbon steel and different steel alloys.
The 7018 is a low-hydrogen electrode whose main selling point is a deeply penetrating arc and heavy-duty use. Although it is an all-position electrode, it only runs on either a DCEP (reverse polarity) or an AC current. The two produce the best quality welds with a low risk of porosity, especially for high-strength steel applications.
The Bottom Line
When choosing the electrical current, you may want to consider one that is compatible with your applications or the type of welding you intend to perform. The first step when choosing welding polarity is checking manufacturer instructions on welding polarity. It is also recommended to experiment on a small piece of metal to help you pick the ideal polarity for your type of welding or specific application.
The best part about stick welding polarity is that it is more flexible, and most applications can use DCEP, DCEN, or even an AC current. As such, it would be of great help to get a stick welder that is designed to run on either polarity. In fact, most modern machines are equipped with a polarity switch that lets you switch between one polarity to another with a touch of a button.