Welding processes create strong joints between pieces of metal to enhance structural efficiency and integrity. MIG welding is a common form of welding used across a wide range of industries, such as manufacturing, automotive and construction that is favourable for metal assemblies due to its cost-effectiveness and versatility.

Keep reading to learn more about MIG welding and discover what the welding process entails.



What Is MIG Welding?

MIG welding or Metal Inert Gas (MIG) welding is a welding process that uses a constant voltage power to create an electric arc that melts and joins the base metal with a filler wire. An inert shielding gas, like argon or a combination of argon, helium, oxygen and carbon dioxide, is released through the gun simultaneously to protect the weld pool from atmospheric contamination and ensure a strong, clean weld.

Typically, MIG welding is used for heavy-duty welding projects and is suitable for use with many types and thicknesses of metals, including steel, aluminium, and stainless steel. It is often a preferred welding choice due to its faster welding process, resulting in shorter lead times and lower production costs. Its simple operation involves easier-to-learn welding techniques and the ability to produce clean welds with minimal spatter and little to no cleaning and finishing.

The MIG Welding Process

Step 1: Position and Angle

For proper MIG welding, correct gun position and angle are essential to prevent filler sagging or rolling. MIG can weld in flat, horizontal, vertical, and overhead positions. The work and travel angles should also be considered according to the type of weld and metal involved.

●     Travel angle (angle relative to the gun in a perpendicular position): 5 to 15 degrees from perpendicular is ideal; beyond 20 to 25 degrees can cause more spatter and arc instability.

●     Work angle (the gun position relative to the angle of the welding joint): Varies with the welding position and joint configuration.

Step 2: Speed

The speed at which the gun moves across the wire will influence the shape and quality of a weld. The optimum welding speed depends on the size of the weld puddle in relation to the joint thickness.

Step 3: Modes of Metal Transfer

Metal transfer in MIG welding describes how the electrode moves through the arc into the weld puddle:

●     Short-circuit welding: Uses low current and voltage ranges to create a small, controlled weld pool. It is ideal for thin sections and out-of-position welding but is susceptible to incomplete fusion defects in thick sections.

●     Globular transfer: Requires higher current and voltage levels, producing large, irregular metal drops. This process is limited to flat-position welding and can cause inconsistent penetration and defects.

●     Spray welding: Uses high current and voltage for a high deposition rate and deep penetration, ideal for thicker materials, with strong, clean welds and minimal spatter.

●     Pulsed mode: Lower heat input makes this method ideal for thinner materials, transferring controlled droplets with low heat input, creating spatter-free welds.

At Cotmor Tool and Presswork, we have 60 years of experience offering in-house welding and assembling services at our West Midlands plant. With a strong client base in the UK and abroad, our range of services, from deep-drawn metal pressings to metal assemblies, are tailored to the needs of each client. To request a quote, get in touch with one of our team today!