A Complete Guide to Different Types of Welding Processes

Welding remains one of the essential joining methods in fabrication and manufacturing—whether you’re building structures, components, or precision assemblies. In simple terms, welding is a process by which two or more parts are fused together by heat, pressure, or both, to form a joint as the materials cool and solidify.

This article aims to provide a comprehensive yet accessible overview of the major welding processes, how they differ, where they are applied, and how to select the right technique for your application.

I. What Is Welding? – The Basics

At its simplest, welding is the coalescence of two or more workpieces through heat or pressure. However, the science behind it is much deeper — involving metallurgy, thermal transfer, and mechanical bonding.

Depending on how the joint is created, welding processes are generally divided into two main categories:

1. Fusion welding: The base material is melted, often with filler metal added. Examples include arc welding, laser welding, and gas welding.

2. Solid-state welding: No melting occurs. The joint is formed by atomic bonding under heat and/or pressure. Examples include friction stir welding and ultrasonic welding.

All welding processes require three essential components:

• A heat source — such as an electric arc, flame, laser beam, or mechanical friction.

• Shielding — to protect the molten weld pool from atmospheric gases like oxygen or nitrogen.

• Filler material (optional) — added to strengthen or shape the joint.

Understanding how each process controls these three variables determines its suitability for specific materials, joint types, and environments.

II. How Welding Processes Are Classified

According to international standards such as ISO 4063, welding and allied processes are categorized by their energy source and mechanism of heat generation. Common classifications include:

1. Arc welding (electric arc produces heat)

2. Resistance welding (heat from electrical resistance)

3. Gas welding (heat from chemical combustion)

4. Beam welding (high-energy beam: laser or electron)

5. Friction and solid-state welding (mechanical heat and pressure)

6. Thermit or exothermic welding (chemical reaction generates heat)

Within these broad families are more than 50 specialized sub-processes. However, the majority of modern industrial welding relies on a core group of arc-based and resistance-based methods.

III. Major Welding Processes – What They Are and When to Use Them

3.1 Shielded Metal Arc Welding (SMAW / “Stick”)

SMAW remains one of the most widely used and versatile processes globally. It employs a flux-coated consumable electrode that conducts current to the workpiece, forming an arc that melts both the electrode and base metal. The flux coating decomposes, producing shielding gas and slag to protect the molten weld pool.

Advantages:

• Equipment is relatively simple and portable.

• Suitable for outdoor or field work, even under adverse conditions (wind, rust, etc).

• Can join thick sections and a variety of ferrous materials.

Limitations:

• Generally slower than semi-automatic or automatic processes.

• More slag clean-up required.

• Weld appearance and finish may require more post-work.

• Less suited to thin materials or high-productivity automated lines.

Typical applications: Construction, repair work, heavy fabrication, structural steel, pipelines in remote locations.

3.2 Gas Metal Arc Welding (GMAW / MIG-MAG)

GMAW uses a continuously fed wire electrode and a shielding gas — typically argon, CO₂, or a blend. Variants include MIG (metal inert gas) for non-ferrous materials and MAG (metal active gas) for steel.

Advantages:

• High welding rates, good for production environments.

• Wire feed and semi-automation reduce manual intervention.

• Cleaner welds, less slag (depending on transfer mode).

Limitations:

• Requires good material cleanliness and preparation (for best results).

• Shielding gas may be impacted by wind if used outdoors.

• Equipment complexity and cost higher than simple stick welding.

Typical applications: Sheet-metal fabrication, automotive, manufacturing plants, pipework, where high throughput is needed.

3.3 Flux-Cored Arc Welding (FCAW)

This process is similar to GMAW in that a continuous wire is used, but the wire is tubular and contains flux within it (sometimes self-shielding, sometimes gas-shielded).

Advantages:

• Good productivity, useful for thicker sections.

• Some variants are more tolerant of rust and surface contaminants.

• Outdoors and on-site use feasible especially with self-shielding types.

Limitations:

• May produce more smoke/fume and spatter—ventilation is important.

• Requires skill to manage parameters and monitor defects (porosity, slag).

• Wire cost may be higher; consumable care matters.

Typical applications: Construction, ship-building, heavy fabrication, repair work, where high deposition rate and field portability matter.

3.4 Gas Tungsten Arc Welding (GTAW / TIG)

A non-consumable tungsten electrode produces the arc; filler metal is added separately if needed. Shielding gas (often inert) protects the weld zone. This process is noted for excellent weld quality and precision.

Advantages:

• High precision, low distortion, clean welds—ideal for critical applications.

• Can weld thinner materials and exotic alloys (aluminium, stainless, titanium).

Limitations:

• Slower than other methods.

• Requires high welder skill and more complex equipment.

• Less suited for high volume/high deposition production.

Typical applications: Aerospace, high‐spec fabrication, precision pipework, aluminium vessel manufacture, decorative work.

3.5 Submerged Arc Welding (SAW)

This is a mechanised process in which the arc is submerged beneath a granular flux; the operator cannot directly see the arc. It offers very high deposition rates and deep weld penetration.

Advantages:

• Excellent for thick plates, long continuous welds, heavy production.

• Very efficient, minimal spatter and good weld quality when set up properly.

Limitations:

• Equipment is bulky, less portable, layout must accommodate flux recovery and handling.

• Typically limited to flat or horizontal positions, thicker materials.

• Less flexible for smaller or complex geometry.

Typical applications: Large structural steel components, shipbuilding, pressure vessels, heavy‐industry fabrication.

3.6 Resistance Welding (Spot, Projection)

Heat is generated by passing a high current through the parts being joined, under pressure. Usually no filler is required, and the joint is generated quickly.

Advantages:

• Fast cycle times, highly automatable, minimal filler, limited distortion.

• Ideal for joining sheet metal in high volume manufacturing (such as automotive).

Limitations:

• Thicker sections or non-overlap joints may not suit.

• Setup and tooling cost may be high; joint access and electrode maintenance required.

Typical applications: Automotive body assembly, appliance manufacture, high‐speed fabrication lines.

3.7 Beam and Friction/solid-state Processes (laser, electron beam, friction stir)

Modern manufacturing increasingly uses advanced techniques such as:

• Laser Beam Welding (LBW): high precision, low distortion, ideal for thin sheets and automated systems.

• Electron Beam Welding (EBW): operates in vacuum; deep, narrow welds with minimal contamination.

• Friction Stir Welding (FSW): a rotating tool plastically deforms the joint — widely used for aluminum structures in aerospace and rail.

• Ultrasonic Welding: high-frequency vibrations create frictional heat; used in electrical, plastic, and foil joining.

These processes offer excellent repeatability and weld integrity for specialized high-value applications.

4. Factors to Consider When Choosing a Welding Process

Selecting the correct process involves technical, economic, and practical evaluation:

5. Welding Safety and Quality Assurance

Welding is inherently hazardous — involving intense heat, radiation, and fumes. Safe operation and consistent quality depend on proper preparation, protection, and inspection.

Safety essentials:

• Use a welding helmet with appropriate shade lens (DIN 10–13).

• Fire-resistant gloves, aprons, and clothing.

• Adequate ventilation or fume extraction, especially for FCAW and stick.

• Grounding and cable inspection to prevent electrical hazards.

• Fire protection: remove flammable materials within 10 meters.

• Eye and face protection for bystanders.

Quality control:

• Follow a qualified Welding Procedure Specification (WPS).

• Perform Non-Destructive Testing (NDT) — visual, radiographic, ultrasonic.

• Maintain preheat and interpass temperature control.

• Record process parameters digitally for traceability.

6. Frequently Asked Questions (FAQs)

Q1. What’s the easiest welding process to learn?

• For beginners, MIG welding offers a good balance of control, visibility, and speed. It’s widely used in workshops and manufacturing because of its user-friendliness.

Q2. Why does welding cause metal distortion?

• Uneven heating and cooling cause differential expansion and contraction, leading to warping. Reducing heat input, using backstep techniques, or fixtures can help control it.

Q3. What’s the difference between MIG and TIG welding?

• MIG uses a consumable wire electrode and is faster; TIG uses a non-consumable tungsten electrode and provides cleaner, more precise welds — ideal for thin materials and aesthetic joints.

Q4. How does shielding gas affect weld quality?

• The right gas mixture stabilizes the arc, improves penetration, and reduces oxidation. For example, CO₂ increases penetration but can cause more spatter; argon provides cleaner welds.

Q5. Can welding be automated?

• Yes — processes like MIG, TIG, and SAW are commonly integrated with robotic or cobot welding systems. Automation improves repeatability, reduces labor dependency, and enhances productivity.

Conclusion.

From the simplicity of stick welding to the sophistication of laser and friction stir methods, each welding process has its place in modern manufacturing. Selecting the right process involves understanding material behavior, desired joint properties, cost constraints, and operational conditions.

Professionals in fabrication, automotive, shipbuilding, or aerospace must balance productivity, quality, and safety — and that starts with mastering the fundamentals of the welding process itself.

By combining process knowledge with modern control technologies and automation systems, industries can achieve stronger, cleaner, and more efficient welds — essential for today’s precision-driven manufacturing world.

Related articles:

1. 10 MMA Welding Processes Flaws And Megmeet’s Solutions

2. GMAW vs. CO2 Welding: A Comparison of Two Metal Arc Welding Processes

3. How to Weld Vertical: Tips and Techniques for Various Processes

4. Gas-shielded arc welding processes (TIG/MIG/MAG)

5. Welding Quality Assurance & Quality Control Processes