How to MIG Weld, Step-by-Step Guide for Beginners

MIG welding (Metal Inert Gas), also known as Gas Metal Arc Welding (GMAW), is one of the most common welding methods for beginners and professionals. It uses a continuously fed wire electrode and shielding gas to create strong, clean welds. Because of its ease of use and versatility, MIG welding is often the first process new welders learn.

Safety First: Government Guidance

Before striking an arc, safety must come first. Welding involves intense heat, UV light, fumes, and electrical hazards. Federal agencies provide guidance you should follow every time you weld.

OSHA Welding, Cutting, and Brazing Safety explains personal protective equipment, ventilation, and safe work practices.
NIOSH Welding Fume Safety highlights potential hazards from fumes and offers control methods.

Basic safety checklist:

Use a welding helmet with proper filter shade and wear safety glasses underneath.
Wear flame-resistant clothing and heavy gloves.
Ensure good ventilation or use local exhaust hoods to control fumes.
Keep fire extinguishers nearby and never weld near flammable materials.

Tools and Equipment You Need

To get started with MIG welding, you will need:

A MIG welder (choose size based on material thickness)
MIG gun and ground clamp
Solid wire electrode (ER70S-6 for steel is most common)
Shielding gas (75% argon, 25% CO2 for steel; 100% argon for aluminum)
Wire brush, grinder, clamps, and a clean metal work surface

Step-by-Step: How to MIG Weld

Prepare the metal. Clean rust, oil, paint, or dirt from the weld area. Clean metal equals stronger welds.
Select wire and gas. Match wire diameter to material thickness and use the correct shielding gas.
Connect the ground clamp. A secure connection ensures a stable arc.
Set your machine. Adjust voltage, amperage, and gas flow (20–30 CFH is typical). Always test on scrap first.
Position the gun. Hold at a 5–15 degree angle and keep 1/4–3/8 inch stickout.
Start welding. Pull the trigger, maintain a steady travel speed, and watch the weld pool.
Check your bead. Look for porosity, undercut, or lack of fusion. Adjust settings if needed.

MIG Welding Settings Cheat Sheet

Material	Thickness	Wire Size	Gas	Voltage / Amperage
Thin steel (24–20 ga)	0.6–1 mm	0.023 in	75/25 mix	Low voltage, low wire speed
1/8 in (3 mm) steel	3 mm	0.030–0.035 in	75/25 mix	Medium voltage, 100–180 A
1/4 in (6 mm) steel	6 mm	0.035–0.045 in	75/25 mix	Higher settings, multi-pass
Aluminum	0.030–0.045 in	100% Argon	Spray or pulsed	Use spool gun if possibl

Advantages & Disadvantages

Research Highlights

Studies show MIG welding produces fine metal fume particles, often under 1 micron, containing manganese, chromium, and iron. Long exposure without controls can be harmful, which is why OSHA and NIOSH stress proper ventilation and respiratory protection.

Academic studies also confirm that voltage, wire feed speed, and travel speed all affect weld bead strength, penetration, and fume generation. Optimizing these settings improves both weld quality and safety.

Troubleshooting MIG Welds

Porosity: Usually from dirty metal or insufficient shielding gas.
Spatter: Often caused by too much voltage or incorrect stickout.
Lack of fusion: Travel speed too fast or low amperage.
Burn-through: Too much heat on thin material, switch to smaller wire or lower settings.

FAQs About MIG Welding

Do I need gas for MIG welding?
Yes, shielding gas is required unless you are using flux-cored wire, which is a different process.

What settings do I use for 1/8 inch steel?
Start with 0.030 in wire, 75/25 gas, and about 18 volts with 150 amps. Adjust as needed.

Are MIG weld fumes dangerous?
Yes, fumes can be hazardous if not controlled. Always follow CDC/NIOSH guidance.