What is ARC Welding? The Definitive 2025 Beginner's Guide

What is ARC Welding (MMA/Stick)?

ARC welding is a fusion welding process that uses an electric arc to generate the intense heat required to melt metal. While MIG and TIG are also technically "arc welding" processes, in the industry, the term "ARC welding" most commonly refers to Manual Metal Arc (MMA) welding, also known as Stick welding or Shielded Metal Arc Welding (SMAW).

The defining feature of this process is the use of a consumable electrode (the "stick" or "rod") coated in a specialized material called flux. When the operator strikes an arc between the electrode and the workpiece, both the metal core of the electrode and the base material melt. The electrode core serves as the filler material to form the weld bead. Simultaneously, the flux coating vaporizes, creating a protective gas shield and a layer of slag that protects the molten weld pool from atmospheric contamination.

This self-shielding nature makes ARC welding highly versatile and uniquely suited for challenging environments, including windy outdoor conditions and less-than-ideal material preparation.

How ARC Welding Works: A Step-by-Step Breakdown

ARC welding is a robust process, but achieving high-quality results requires understanding the sequence of operations and the function of the consumables.

1. 1
   Setup and Circuit Completion The welder (power source) is connected to an electrode holder (stinger) and a ground clamp. The ground clamp is attached to the workpiece, and the consumable electrode is secured in the holder. The machine is set to the appropriate amperage and polarity for the electrode.
2. 2
   Striking the Arc To initiate the process, the operator must "strike" the electrode against the workpiece—either by tapping or scratching the surface—to complete the electrical circuit. This creates a high-temperature electric arc between the tip of the electrode and the base metal.
3. 3
   Melting the Electrode and Base Metal The intense heat of the arc (up to 3500°C) instantly melts the base metal, forming the weld pool. Simultaneously, the metal core of the electrode melts, and droplets of molten filler metal are transferred across the arc into the pool.
4. 4
   The Role of the Flux Coating As the electrode melts, the flux coating decomposes due to the heat. This decomposition serves two critical functions: creating a protective gas shield to displace the atmosphere, and forming a layer of molten slag.
5. 5
   Forming the Weld Bead The operator moves the electrode along the joint, maintaining a consistent arc length and travel speed. As the electrode is consumed, the operator must continuously feed it into the joint. The molten metal solidifies behind the arc, forming a strong fusion joint.
6. 6
   Cooling and Cleanup As the weld cools, the slag solidifies on top of the bead. This slag layer must be chipped away (using a chipping hammer) and brushed clean to reveal the finished weld.

The Role of Flux and Slag

The flux coating is what differentiates ARC welding from MIG and TIG. It is a complex chemical mixture designed to perform several essential functions during the high-temperature reaction of the arc:

• Shielding: The vaporization of the flux creates a protective gas cloud (often rich in CO2 and hydrogen) that prevents atmospheric oxygen and nitrogen from interacting with the molten metal, which would cause brittleness and porosity.
• Deoxidation and Cleansing: The flux contains elements (such as manganese and silicon) that actively scavenge impurities and oxides from the weld pool, cleansing the metal.
• Arc Stabilization: Compounds in the flux, such as potassium, help to ionize the air gap, maintaining a stable and consistent electric arc.
• Alloying: Flux can introduce specific alloys into the weld deposit to enhance its mechanical properties (e.g., strength, ductility, corrosion resistance).
• Insulation (Slag): The molten flux solidifies as slag on top of the weld bead. This layer acts as an insulating blanket, slowing the cooling rate of the weld, which improves its metallurgical properties and helps shape the bead profile.

Essential ARC Welding Equipment

ARC welding setups are characterized by their simplicity and portability.

• The ARC Welder (Power Source): Converts mains electricity into the required welding current.
• Electrode Holder (Stinger): The insulated clamp that the operator holds. It securely grips the electrode and transfers the welding current to it.
• Ground Clamp: A heavy-duty clamp attached to the workpiece to complete the electrical circuit. A strong, clean connection is vital for a stable arc.
• Electrodes (Rods): The consumable filler material coated in flux.
• Safety Gear: Essential PPE includes an auto-darkening helmet, heavy-duty welding gauntlets, fire-resistant clothing, and safety boots. A chipping hammer and wire brush are also necessary.

ARC Welding Power Sources Explained

The welding machine is the heart of the process. ARC welding specifically requires a Constant Current (CC) power source. This means the machine strives to maintain the set amperage (current) even if the operator varies the arc length (which changes the voltage).

Inverter vs. Transformer Technology

• Transformers: The traditional technology. These machines are heavy and less energy-efficient, but extremely durable. They typically provide AC output, though some (rectifiers) can provide DC.
• Inverters: Modern technology utilizing advanced electronics. Inverters are significantly lighter, highly energy-efficient, and offer superior arc control. They provide a very smooth DC output, making welding easier.

Duty Cycle and OCV

• Duty Cycle: A critical specification indicating how long a welder can operate continuously within a 10-minute period before overheating. A 60% duty cycle at 200A means the machine can weld for 6 minutes at 200A, then requires 4 minutes of cooling.
• Open Circuit Voltage (OCV): The voltage measured at the terminals when the machine is on but not welding. Higher OCV generally makes it easier to strike and maintain an arc, particularly with difficult-to-run electrodes.

Modern Inverter Features

Modern inverter welders often include features that significantly improve usability:

• Hot Start: Provides a brief boost of current when the arc is initiated. This helps prevent the electrode from sticking and ensures reliable arc ignition.
• Arc Force (or Dig): Detects when the arc length is becoming too short and automatically boosts the amperage momentarily. This prevents the electrode from "stubbing out" (extinguishing the arc) when the operator pushes the rod close to the weld pool.
• Anti-Stick: If the electrode does stick to the workpiece, this feature automatically cuts the welding current, allowing the operator to easily break it free without damaging the electrode.

Understanding Welding Electrodes (Rods)

The electrode is the most critical consumable in ARC welding. Choosing the correct rod determines the strength, quality, and characteristics of the finished weld. Electrodes are classified using a standardized system (e.g., AWS in the US, ISO internationally).

Decoding Electrode Classifications (Example: E6013)

• E: Indicates an Electrode.
• 60: Indicates the minimum tensile strength of the weld deposit in thousands of pounds per square inch (PSI) (i.e., 60,000 PSI).
• 1: Indicates the welding positions the rod can be used in (1 = All positions; 2 = Flat and horizontal only).
• 3: Indicates the type of flux coating and the electrical current (polarity) that can be used.

Common Electrode Types and Uses

While there are hundreds of specialized electrodes, three main types cover most general fabrication and repair work:

Rutile Electrodes (e.g., E6013)

The most common general-purpose rod. E6013s are very easy to use, produce a smooth weld profile, run well on AC and DC, and the slag is easy to remove. They are ideal for general fabrication of mild steel, sheet metal, and non-critical repairs. They offer moderate penetration.

Cellulosic Electrodes (e.g., E6010, E6011)

These rods provide a very deep, aggressive penetration and a fast-freezing slag. They are essential for root passes in pipe welding and for welding on rusty, dirty, or painted materials where deep penetration is crucial. They require a higher skill level to operate.

Basic (Low Hydrogen) Electrodes (e.g., E7018)

These are high-strength rods designed for critical structural work, heavy machinery, and high-carbon steels susceptible to cracking. They produce a very strong, ductile weld deposit with excellent mechanical properties.

Electrode Storage and Handling

Proper storage of electrodes is critical to weld quality. The flux coatings are hygroscopic, meaning they absorb moisture from the atmosphere. Moisture breaks down during the welding process, introducing hydrogen into the weld pool, which can lead to porosity and hydrogen-induced cracking (embrittlement).

• General Purpose Rods (E6013, E6011): Should be stored in a dry, sealed container at room temperature.
• Low Hydrogen Rods (E7018): Require strict storage controls. They must be kept in a dedicated electrode stabilization oven (rod oven) at temperatures typically between 120°C and 150°C once the hermetically sealed package is opened.

ARC Welding Polarity (AC vs. DC)

Modern inverter welders often offer the choice between AC (Alternating Current) and DC (Direct Current).

DC Welding (Direct Current)

DC provides a smoother, more stable arc than AC and is generally preferred. It offers two polarity options:

• DCEP (DC+, or Reverse Polarity): The electrode is positive. This configuration maximizes penetration and is used with most electrodes, including E7018 and E6010.
• DCEN (DC-, or Straight Polarity): The electrode is negative. This results in less penetration and a higher deposition rate, sometimes used for thinner materials.

AC Welding (Alternating Current)

While the arc is less smooth than DC, AC is necessary for overcoming "arc blow." Arc blow is a phenomenon where the magnetic field generated in the workpiece deflects the DC arc, making it wander uncontrollably. AC's rapidly reversing polarity prevents these magnetic fields from establishing.

Common Applications: Where is ARC Welding Used?

ARC welding excels in environments where portability, robustness, and versatility are prioritized over absolute precision.

• Structural Steel Erection: Used extensively on construction sites for welding beams and structural components.
• Heavy Equipment Repair: Ideal for fixing thick, damaged components on agricultural or industrial machinery in the field.
• Pipeline Welding: Used for cross-country pipeline installation due to its portability and deep penetration capabilities.
• Shipbuilding and Maintenance: Used for heavy fabrication and repairs in dockyards.
• General Maintenance and Farming: The preferred method for quick, durable repairs, even when conditions are dirty or rusty.

The Advantages and Disadvantages of ARC Welding

How Does ARC Compare to Other Welding Processes?

Joint Preparation

While ARC welding is forgiving of poor material conditions, proper joint preparation is essential for achieving maximum strength.

• Cleaning: For critical welds, remove heavy rust, mill scale, paint, and grease.
• Beveling: On materials thicker than 5mm, the edges of the joint should be beveled (ground to an angle). This ensures the arc can reach the root of the joint, guaranteeing complete penetration and fusion.
• Fit-up: Ensure the joint fit-up is consistent. Excessive gaps can lead to burn-through or poor fusion.

Basic ARC Welding Techniques (CLAMS)

Mastering ARC welding involves controlling several key variables, summarized by the acronym CLAMS: Current, Length of arc, Angle, Manipulation, Speed.

Current (Amperage)

The correct amperage depends on the electrode diameter and material thickness. Consult the manufacturer's recommended range. If the amperage is too low, the arc will be hard to maintain; if it is too high, it will cause excessive spatter and undercut.

Length of Arc

The distance between the electrode tip and the workpiece is critical. The arc length should generally be about the same as the diameter of the electrode's metal core (e.g., 3mm rod = 3mm arc length). As the electrode burns down, the operator must continuously feed it downwards to maintain this distance.

Angle (Travel Angle)

The electrode should generally be held perpendicular to the joint and "dragged" (pulled) in the direction of travel, angled back about 10-15 degrees.

Manipulation

This refers to the movement of the electrode. The operator may move the rod in a straight line (a "stringer") or use a side-to-side motion (a "weave") to fill wider gaps. Different electrodes require specific manipulation (e.g., the "whip and pause" technique for E6010).

Speed (Travel Speed)

The travel speed must be consistent. Moving too fast results in a thin, weak bead. Moving too slow can cause excessive heat buildup or burn-through.

Welding Positions

ARC welding can be performed in all positions, but the technique must be adapted to counteract gravity.

• Flat and Horizontal (1G/2G): The easiest positions. Gravity helps hold the molten metal in the joint.
• Vertical (3G): More challenging. Vertical-Up (welding from bottom to top) is generally preferred for thicker materials as it provides better penetration.
• Overhead (4G): The most difficult position. Requires precise control of arc length and amperage to prevent the molten metal from falling out of the joint.

Common ARC Welding Defects and How to Fix Them

ARC Welding Safety: Essential Precautions

ARC welding is a heavy-duty industrial process that generates significant hazards, including intense UV radiation, sparks, fumes, and the risk of electric shock.

Fumes and Ventilation

ARC welding produces significant amounts of smoke and fumes due to the burning of the flux coating. These fumes can be hazardous.

• Ventilation is Critical: Always weld in a well-ventilated area. When welding indoors, local exhaust ventilation (fume extraction) is essential.
• Respiratory Protection: Wear a suitable respirator if ventilation is inadequate or when welding certain materials like galvanized steel.

Protective Gear

• Welding Helmet: An auto-darkening helmet (shade 10-13) is essential to protect against arc flash and UV radiation.
• Heavy-Duty Gauntlets: Thick leather gloves are necessary to protect against heat, sparks, and electric shock.
• Fire-Resistant Clothing: Wear a welding jacket or heavy cotton long-sleeved shirts. Synthetic materials will melt and cause severe burns.

Electric Shock

ARC welding uses live electrical circuits.

• Dry Conditions: Never weld in wet conditions. Ensure gloves and clothing remain dry.
• Inspect Equipment: Regularly check electrode holders and cables for damage or exposed wiring.

Why Trust Premier Welding?

Mastering the fundamentals of ARC welding is essential for anyone involved in metal fabrication or repair. With 45 years of dedicated experience, Premier Welding provides the expertise and equipment necessary for success. We understand the demands of heavy-duty welding and rigorously test the machines and consumables we supply—from advanced inverter units to specialized electrodes—to ensure they meet professional standards. When you choose Premier Welding, you gain a partner committed to supporting your skills development with reliable tools and expert advice.

Frequently Asked Questions (FAQ)

Is ARC welding the same as Stick welding?

Yes. In the industry, ARC welding, Stick welding, Manual Metal Arc (MMA), and Shielded Metal Arc Welding (SMAW) all refer to the same process using a flux-coated consumable electrode.

Is ARC welding easy to learn?

ARC welding has a moderate learning curve. While the basic concept is simple, mastering the technique—particularly striking the arc without sticking and maintaining a consistent arc length—takes practice. It is generally considered harder to master than MIG welding but easier than TIG.

Can you ARC weld aluminium?

While technically possible using specialized aluminium electrodes, it is difficult, produces poor quality results compared to TIG or MIG, and is generally not recommended for most applications.

What is the best welding rod for beginners?

The E6013 (Rutile) electrode is widely considered the best for beginners. It is easy to strike, provides a stable arc, runs on both AC and DC current, and produces a smooth weld bead with easy slag removal.