Arc Welding History, Techniques, And Types

5/5 - (1 vote)

Arc welding is a process that joins metal pieces together. It creates an electrical arc between a welding electrode and the joined base metals. The high heat generated by the arc melts the metals at the point of contact. As the metals liquefy, they intermix and solidify as one unified piece.

In this article, we will explore arc welding in greater detail. We will examine how arc welding utilizes electricity to fuse metals. We will also learn about the various types of arc welding and their specific applications. So read on!

History of Arc Welding

Welding has a long history, going back thousands of years. Around 3,000 B.C., people in places like Egypt and the eastern Mediterranean first started joining metal pieces together. They did this by heating and hammering the metal until it stuck together. This simple method was the start of welding as we know it today.

1800s

Discovery of electric arc and initial experiments in metal joining.

1887

Nikolai Bernardos receives the first patent for electric arc welding using carbon electrodes.

1890s

Nikolai Slavyanov and C.L. Coffin develop metal electrode arc welding techniques.

1910s

Advancements in arc control lead to wider adoption of arc welding.

1927

Hobart introduces coated metal electrodes, improving arc stability.

1930s

Automatic and submerged arc welding methods are developed for mass production.

1940s

Further advancements in arc welding, including flux-cored welding, occurred during WWII.

1950s

Transistor-controlled power supplies enhance arc welding precision and versatility.

1960s

MIG and TIG welding expanded material options for arc welding.

1970s

Robotics were integrated into arc welding processes, increasing automation.

1980s

Microprocessor-controlled power supplies further refine precision in arc welding.

Welding Nowadays

Arc welding continues to advance, remaining critical across multiple industries.

How Arc Welding Works?

The arc welding process takes a few steps. The welder carefully positions the electrode close to the joined metals to initiate the process. Proper alignment ensures a consistent arc between the rod and metals.

Next, the operator triggers the arc using one of two techniques: striking the electrode on the metals or activating a high-frequency starter on non-consumable rods. This generates intense heat, reaching temperatures of several thousand degrees Fahrenheit.

This extreme heat melts the end of the electrode and a small area on the surface of the metals. The liquefied pool enables the molten metals to intermix freely. As the rod melts, it deposits weld metal into the joint, while the arc fuses the metals into a cohesive bond. Some methods utilize additional filler metal to reinforce the joint.

The operator maintains a steady travel speed and controlled arc length throughout the welding process. This ensures even heat distribution for a uniform joint. Too fast or too slow will create imperfections.

After applying the desired weld passes, the joint undergoes natural cooling. Once sufficiently cooled, the welded metals are inspected per industry guidelines. Properly executed welds meet established criteria for strength and appearance.

Types of Arc Welding

Shielded Metal Arc Welding (SMAW)

Also called stick welding. It uses a flux-coated consumable electrode that also provides shielding gas. A versatile, simple and inexpensive process but requires more skill.

Gas Tungsten Arc Welding (GTAW)

Also known as TIG welding. Uses a non-consumable tungsten electrode and inert shielding gas from an external cylinder. Allows high-quality welds on thinner metals but slower.

Gas Metal Arc Welding (GMAW)

Also called MIG welding. Uses a consumable wire electrode fed continuously and inert shielding gas. Higher welding speeds than TIG but requires more equipment.

Flux Cored Arc Welding (FCAW)

MIG welding uses a tubular wire electrode with flux inside to shield the weld so no external gas is needed.

Submerged Arc Welding (SAW)

It uses a bare wire electrode, submerging the arc under flux. Used in automated systems to enable high deposition rates but has limited visibility.

Types of Electrodes Used in Arc Welding

Consumable Electrode Methods

In consumable electrode arc welding, the electrode is continuously fed into the weld pool as it melts. This transfers the electrode material into the joint to become part of the weld. Common consumable electrode methods include:

Shielded metal arc welding (SMAW).
Gas metal arc welding (GMAW).
Flux-cored arc welding (FCAW).
Submerged arc welding (SAW).

These allow higher deposition rates but require replacing electrodes.

Non-Consumable Electrode Methods

Non-consumable electrode arc welding uses an electrode that does not melt away or deposit material. The electrode only creates the arc for melting the base metal. Gas tungsten arc welding (GTAW) is the most widely used non-consumable electrode method. It allows for intricate welds but has slower deposition rates. The electrode must be ground to sharpen its tip as it erodes with use.

Arc Welding Techniques

Welding Positions

Flat Position

The flat position in arc welding has the weld plane horizontal and the weld face upwards. This allows gravity to help keep the molten weld puddle flush to the joint. Flat welding is typically the simplest, as the puddle can spread smoothly without the risk of sagging or falling. Good fit-up and angles are still required for proper fusion.

Horizontal Position

Horizontal arc welding position places the weld plane vertically, and the weld faces horizontally. Since gravity pulls the puddle downward, more welder skill is needed to prevent sagging or separation. The electrode angle and travel technique must counteract the effects of gravity in horizontal welding.

Vertical Position

In a vertical position, the weld plane and the weld face are oriented vertically. The welder must deposit the weld bead upward while preventing the puddle from falling down the joint. Controlling the molten puddle requires precise electrode angles and movements to achieve quality vertical welds.

Overhead Position

Overhead arc welding has the weld plane horizontal and the weld face downwards. Since gravity pulls the puddle straight down, overhead welding is the most difficult position. The welder must master special electrode angles and travel techniques to control the puddle and achieve proper fusion overhead.

Joint Types

Butt Joints

Butt joints are between two pieces aligned end-to-end. Variations like square, single V, double V, or single bevel change the weld preparation, but all require filling the seam evenly. Proper fit-up is crucial for complete fusion in butt joint welds.

Lap Joints

Lap joints overlap two plates aligned parallel to each other. The weld seam is deposited along the overlapped area. Care must be taken to avoid a lack of fusion between the laps. Bead placement sequence can help minimize distortion.

Tee Joints

Tee joints are between two plates meeting at right angles, like a T-shape. The weld is typically made on one side of the seam. Careful technique ensures penetration into the base metals while avoiding burn-through.

Corner Joints

Corner joints connect two plates that meet at an angle other than 90 degrees. The weld follows the angled seam and must fuse with both plate edges. Flux core welding is commonly used for corner joints.

Edge Joints

Edge joints welded between two overlapping members require careful seam following to prevent cracks. Weaving or oscillation penetrates the top and bottom plates along the edge.

Electrode Angles and Travel

Proper electrode angles relative to the joint direct heat into the weld zone for good fusion. Travel speed affects heat input and penetration. Excessive speed causes undercut, while too slow speed creates a wide weld with possible burn-through. Weaving motions aid penetration for deep welds.

Multiple Passes and Sequencing

Thick joints require multiple passes to fill the groove and ensure full penetration. Each new pass is welded to overlay and bond with the previous layer. Passes are sequenced from the bottom up and sides towards the centre to provide a solid joint.

Shielding Gas Flow

In GMAW and GTAW welding, the inert shielding gas flows steadily around the arc to protect it. Ideal flow rates prevent turbulence while adequately displacing the atmosphere. Too little flow allows contamination, while too much thins and destabilizes the arc.

Filler Metals and Parameters

Matching the filler metal to the base materials and adjusting the voltage, wire speed, and other welding factors produces a stable arc with proper bead shape and penetration. This tuning of parameters is essential for quality results.

Effects of Welding Parameters

Current, arc length, travel speed, electrode angle and other variables affect heat input, penetration profile, bead shape and weld quality. Operators control parameters like amperage and voltage to adjust the arc and puddle dynamics.

Takeaway

As we have seen, arc welding has evolved over the past century into an essential fabrication process used across industries. Mastering its various techniques and applications requires extensive training and skill—as I’ve experienced firsthand as a welder. While fundamental methods like SMAW remain widely used for simplicity, continued technological advancements are expanding possibilities for more precise and efficient welding.

The future looks bright for this versatile process that joins everything from delicate instruments to massive ships and bridges. With dedicated welding professionals pushing new boundaries, arc welding will continue improving lives and building our world.

Arc Welding History, Techniques, and Types