How to Weld With a Mig Welder?

MIG Welding, also known as Metal Inert Gas welding, is a versatile, strong, and precise process suitable for both novice and seasoned welders, offering a solution for metal joining. This guide covers MIG welding basics, including equipment selection, safety measures, and technique perfecting, aiming to equip DIY and professional users with essential knowledge for successful welding endeavors.

What Is MIG (Gas Metal Arc Welding) Welding And How Does It Work?

MIG welding is a semi-automated technique that uses an electric arc to fuse metals, creating a durable bond between electrodes and joined pieces. Gas, derived from welding wire's bare nature, requires external shielding gas protection like argon to prevent defects in the weld pool from atmospheric gases.

So, how does the MIG welding work? To start a welding process, depress the MIG torch trigger, forming an arc between the gun, metal surface, and welder, and delivering shielding gas.

The welding process is stopped by disabling the electrical circuit, causing the wire feed and gas distribution to cease, and the arc heat melts the metal and welding wire, preventing contamination.

Why Is MIG Welding So Popular?

MIG welding is renowned for its user-friendliness, rapid capabilities, and adaptability across various metals, making it suitable for multiple applications in automotive, construction, manufacturing, and metal fabrication.

MIG welding is a popular choice for beginners due to its simplicity and minimal skill demands. This semi-automated process handles amperage, voltage, and wire feed, while the welder concentrates on travel speed, travel angle, and weld direction.

MIG (Metal Inert Gas) Welding Equipment And Important MIG Welder Parts

Similar to the process, MIG welding equipment is relatively uncomplicated. Once you understand the function of each component, you can proficiently weld various metals with ease. The fundamental components of MIG welding equipment include:

• Power supply (MIG welder)
• MIG gun
• Wire feeding mechanism
• Welding wire
• Shielding gas

Comprehending the significance and function of each of these components will significantly aid in your acquisition of MIG welding skills. This is why we will initially provide a brief explanation of them.

MIG Welding Machine (Power Supply)

The welding machine is a crucial part of any welding system, harnessing power from the electrical grid or generator to create a welding arc. The output power, which includes current and voltage, regulates the weld's heat and arc length.

The power grid provides a consistent voltage of 110 V (110/115), 208V (200), 230V (220/240), 460V (440-480), or 600 VAC for Alternating Current, while MIG welders operate using DC current. Consequently, the welders convert and produce a high-current electrical arc between the welding wire (electrode) and the workpiece.

A MIG power supply must maintain a stable current and consistent voltage to facilitate transformation during welding. Without constant voltage, arc length fluctuations can cause electrode stubing or burn back, while an increase in voltage can cause an excessively long arc.

MIG Gun

MIG guns are handheld accessories designed to facilitate control over the welding process, including start, stop, travel angle, speed, and direction of the weld. These ergonomic devices are relatively straightforward, featuring a trigger that, once activated, initiates the welding process, wire feed, and shielding gas supply.

Nevertheless, MIG guns can consist of various consumable components such as contact tips or nozzles, which impact shielding distribution and process control. Despite this, purchasing and replacing these components does not necessitate significant effort or expense.

Wire Feed Mechanism

The wire feed mechanism in the MIG welder is crucial for smooth and consistent MIG wire feed, operated by an electric motor. It communicates with the welder and wire feed speed settings, ensuring consistent welds and ensuring proper functioning of each component.

The mechanism uses drive rolls to guide wire into the liner and MIG gun, ensuring straight feeding without tangling. A tensioner applies correct tension to prevent birdnesting, while the linear guides wire from the wire feeder to the contact tip.

Welding Wire

MIG welding uses wire as a consumable electrode, available in various spool sizes. The wire is fed through a mechanism and into the liner before emerging from the gun, where an arc melts the wire, filling the joint.

MIG wire, similar to base metal, comes in mild steel, aluminum, or stainless steel. Sizes range from 023" to 0.045" for industrial applications, with 030" ideal for hobbyists. Spool sizes range from 2-10 lbs for hobbyists.

Shielding Gas

Shielding gas protects MIG weld pool from contamination, as molten metal absorbs impurities, causing defects like porosity or cracking. Welders use inert gases like argon or CO2.

MIG welding is often considered the most effective shielding gas for mild steel welding due to its lower cost and satisfactory results, although it is not typically used for critical applications.

MIG Welding Basics: Learning How to MIG Weld

The MIG welding system is a straightforward process from weld preparation to post-weld cleaning, unlike TIG (Tungsten inert gas welding). This guide provides a comprehensive introduction to the process, ensuring that beginners don't need to invest significant time in learning before laying their first bead.

Safety First!

Welding poses occupational hazards like burns, radiation, electrical shock, and fire, including MIG welding. Although MIG welding may have less spatter and arc heat than Stick welding, prioritizing personal safety is crucial.

To begin, ensure adequate protection for your skin through the use of personal protective equipment (PPE). This includes donning a welding helmet like the Optrel Helix Quattro 1050.100, or at the very least, safety glasses, leather shoes, gloves, and a jacket. By doing so, a welding mask can safeguard your eyes from the IR/UV radiation produced by the welding arc, while simultaneously shielding your skin from burns caused by molten metal.

Pre-weld clean up

Preparing metal is crucial for all welding techniques, including MIG welding, as it cannot burn through dirt, rust, paint, or mill scale. Contaminants can compromise weld integrity, cause defects, and pose health risks. Burning paint or zinc coatings can emit toxic fumes, causing irritations or illnesses.

Before MIG welding, it's crucial to clean the metal surface thoroughly. For minor contaminants, an old rag can be used, but for stubborn impurities like rust or paint, a wire brush, sanding paper, grinder, or specialized chemicals may be needed. This ensures a high-quality, structurally sound weld.

Following cleaning, align pieces and secure them to the welding table using clamps to maintain even gaps, ensuring consistent results and penetration throughout the welding process.

Choose The Right MIG Wire

The choice of MIG wire depends on the type of metal to be welded, and AWS has classified them as suitable for mild steel, aluminum, and stainless steel welding, for convenience.

MIG welding mild steel with ER70S-2 or ER70S-6 is suitable for various carbon steel applications. ER70S-6 is preferred due to its heat resistance. Both options yield excellent results and uniform weld appearances, with low mill scale or rust levels.

ER70S-6 36" long Tig welding wire 70S-6 10lb box for Mild Steel

If you are about to MIG weld aluminum, you'll need aluminum wires such as ER4043 or ER5356. These are general-purpose aluminum MIG wires that will cover most of your aluminum applications. For stainless steel MIG welding, you are likely to use ER308/308L, ER309, or ER316 stainless steel MIG wires as a hobbyist or occasional welder.

ER4043 Tig Welding Wire 36" long 5lb box

Besides types, you'll have to think about diameters. MIG wires for hobbyists typically come in three different sizes:

• .023-inch, which is suitable for thin materials,
• .030-inch as a decent all-rounder that will cover most of your home projects and repairs
• .035-inch wire for thick metal and higher heat (or even .045-inch if your machine can handle it)

Choose The Proper MIG Welding Shielding Gas

Flux core welding uses self-shielded wire, while MIG welding requires external shielding using inert, semi-inert, or reactive gases like argon or helium. The C25 mixture, a 75% Argon and 25% CO2 blend is the optimal shielding gas for hobbyists and welding enthusiasts of MIG welding steel. This combination provides effective coverage, proper shielding, cleanliness, favorable penetration, minimal spatter, and cost efficiency. Pure CO2 gas shielding is cost-effective for rapid welding thicker materials.

MIG welding aluminum requires argon gas, an inert gas that doesn't react with metals. Pure argon is used for thin aluminum, while helium can enhance heat and penetration for thicker pieces. MIG welding stainless steel can use argon or argon/helium mixtures, with specific tri-gas mixes needed for different grades.

MIG welding indoors requires adjusting the gas flow rate for the gas tank. A recommended flow rate is 15-20 CFM for medium-scale jobs. However, higher flow rates may not provide better protection as they can generate turbulent forces that draw in air and contaminants during the welding process.

Setting Up The MIG Welder

Beginners may struggle with configuring MIG welders due to the need to adjust wire feed speed and voltage based on material thickness. Higher settings result in increased heat and penetration, while voltage affects arc length. Some MIG welders, like the Forney Easy Weld 140 FC-i MIG Machine, have synergic settings or auto-set features that automatically adjust these factors based on material thickness. 

They can benefit from adjustable settings, while experienced welders can fine-tune their settings. For finer adjustments, the machine can be customized manually. Experimentation is necessary to understand different metal thicknesses, and general recommendations include DCEP (direct current electrode positive) connection.

MIG Welding Tips And Techniques

To create an initial weld, use scrap metal with a 3/8-inch stick out and listen for a sizzling sound. Maintain the correct travel angle and work angle, which should be 5 to 15 degrees in all positions. Adjust the work angle for thin metals and control the gun speed to avoid oversized beads and increased heat.

The choice between push or pull MIG welding depends on the application, with push MIG resulting in lower penetration and wider beads, and pull MIG resulting in deeper penetration and narrower beads with increased buildup. The optimal choice depends on the specific application.

Post Weld Finishing

MIG welding is a simple technique, but achieving optimal results requires time and practice. Post-welding, thorough cleaning, and inspection are essential. The weld bead should have a gentle crown and seamlessly integrated edges. Identifying issues like holes, spatter, or uneven welds doesn't require advanced expertise but may suggest corrective actions. 

Common MIG welding defects like porosity, lack of fusion, burn-through, or excessive spatter can be prevented by cleaning the metal, setting appropriate parameters, and using the appropriate welding technique. However, achieving these standards requires practice.

Practice Makes Things Perfect

This guide aims to provide a solid foundation in MIG welding, emphasizing the importance of consistent practice and safety. It encourages starting with simple projects and gradually progressing to more complex ones. 

With dedication and access to the knowledge provided on the website, MIG welding can unlock a wide range of applications. Initial setbacks should not deter one, as proficiency in any profession can be honed through persistent practice. It encourages exploration and reflection on areas for improvement.

How To MIG Weld With a Mig Welder- FAQ

What Is MIG Welding?

MIG welding, also known as Gas Metal Arc Welding, is a semi-automated welding technique that uses an electric arc to unite metals, forming an arc between welding wire and base metal, resulting in a durable bond.

How does the MIG welding work?

To start the welding process, activate the MIG torch trigger, creating an arc between the torch, metal surface, and welder. The wire feed mechanism dispenses MIG wire at the specified speed.

How do you choose the proper MIG welding shielding gas?

The Argon and CO2 mixture, also known as the C25 mixture, is considered the optimal shielding gas for hobbyists and welding enthusiasts, offering extensive coverage, protection, cleanliness, impressive penetration, minimal spatter, and cost-effectiveness.