Drawing of a MIG torch welding a plate joint, showing the wire, the shielding gas and the bead

The full theory of the process, from the power source to the bead, to understand what happens behind the helmet.

Twelve lessons and two appendices on the process that does most of the welding in a shop like ours. It starts from the physics, tells where it came from, works through the equipment, the arc, metal transfer, gases and wires, and ends with what an inspection looks at: defects, safety and qualified procedures.

A free theory course from the Steel Knowledge Hub of Indumor.

Who it is for

Welders who want to understand what they do, technical school students, supervisors and buyers who need to read a procedure. You do not need to know how to weld to start.

Method

Each lesson explains a principle and why it works, brings it down to the shop with numbers and closes with a four-question self-test with hidden answers. It is theory: it does not replace practice hours with an instructor.

Pace

All twelve lessons and both appendices are published. The stick welding course is complete too, and TIG comes next.

12 of 12 lessons published100 %

Part I · The process

What it is, where it came from and what it takes.

1What MIG-MAG welding isWire, arc and gas: the principle, the names of the process and when it fits.Read 2The history of MIG-MAGFrom the bare wire of the 1920s to the software-controlled arc.Read 3The equipment: power source, feeder and gunWhy the power source is constant voltage and what each part of the set does.Read 4The arc: voltage, current and stickoutArc self-regulation and why the gun distance changes the current.Read

Part II · Transfer, gases and wires

What decides how the metal crosses from the wire to the part.

5Metal transfer modesShort-circuit, globular, spray and pulsed: what happens in the arc with each.Read 6Shielding gasesArgon, CO₂ and blends: penetration, spatter, flow rate and standards.Read 7Solid and cored wiresHow to read the classifications and which wire fits each job.Read 8How to set up the machineWire feed speed, voltage, inductance, gun angles and heat input.Read

Part III · In the shop

Joints, defects, safety and procedures.

9Joints, positions and techniqueEdge preparation, positions PA to PG and handling the gun.Read 10Typical MIG-MAG defectsPorosity, lack of fusion, spatter and burn-through: causes and cures.Read 11Safety: fumes, radiation and gasesWhat a welder breathes, sees and touches, and how to stay safe.Read 12Procedures and qualificationWhat a WPS is, how it is qualified and how a welder is qualified.Read

Appendices

AMIG-MAG glossary, Spanish-EnglishThe course terms in both languages of the shop.Read BStarting-point parameter chartStarting values by plate thickness and wire diameter.Read

The other courses

Stick welding course: The easiest process to take to the field, explained from the covering to qualification.
TIG welding course: The cleanest and most precise process, from the tungsten to a pipe root.

Indumor

MIG-MAG welding course