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Slide 001: MIG Welding Equipment & Setup

Slide Visual

MIG Welding Equipment & Setup

Slide Overview

This slide introduces the MIG welding equipment, component functions, and the complete setup procedure. Students will learn the system architecture before touching any equipment.

Instruction Notes

MIG System Components

Power Supply: Converts facility power to welding-grade DC. Most makerspace MIG welders are constant-voltage (CV) machines — the operator sets voltage, and the machine adjusts current automatically to maintain the set voltage. Common ratings: 110V/140A (light duty), 220V/200-250A (medium duty).

Wire Feeder: Feeds electrode wire from the spool through the gun at a controlled speed. The wire feed speed (WFS) directly determines amperage — faster feed = more current. Drive rolls must match the wire type: V-groove for solid wire, U-groove (knurled) for flux-cored.

Drive roll tension: Set just tight enough to feed wire smoothly. Too tight deforms the wire and causes feeding issues. Too loose causes slipping and inconsistent feed. Test: with the trigger pressed and the wire tip against a solid surface, the rolls should slip (not stall the motor or deform the wire).

MIG Gun: Delivers wire, current, and shielding gas to the weld point. - Contact tip: Copper alloy tube that transfers current to the wire. Size must match wire diameter (0.030" tip for 0.030" wire). Replace when worn — an oversized hole causes arc wander - Gas nozzle: Directs shielding gas around the arc. Must be kept clean of spatter - Liner: Teflon or steel tube inside the cable that guides the wire from the feeder to the contact tip. Steel liner for steel wire, Teflon liner for aluminum wire

Gas System: Cylinder → regulator → flowmeter → solenoid (in machine) → gun. The solenoid opens when the trigger is pressed, sending gas 0.5-1 second before the arc starts (pre-flow) and continuing 0.5-1 second after (post-flow).

Work Clamp: Completes the circuit — must make solid metal-to-metal contact with the workpiece. A poor connection causes arc instability, spatter, and potential shock hazard.

Machine Setup Procedure

  1. Connect the work clamp to the workpiece (clean contact point)
  2. Install the correct wire spool and thread wire through drive rolls, into liner
  3. Install the correct contact tip (match wire diameter)
  4. Clean and install the gas nozzle
  5. Connect the gas hose and open the cylinder valve slowly
  6. Set the gas flow rate: 20-25 CFH
  7. Set voltage and wire feed speed for the material/thickness
  8. Run wire through the gun until it extends ½" past the nozzle
  9. Trim wire to ⅜" stickout

Key Talking Points

  1. MIG is a constant-voltage system — you set voltage, wire feed speed controls amperage
  2. Contact tip size must match wire diameter exactly
  3. Drive roll tension: minimum necessary to feed reliably — over-tightening causes problems
  4. Clean the nozzle of spatter regularly — blocked nozzle = no gas coverage = porosity
  5. The work clamp connection is as important as any machine setting

Learning Objectives (Concept Check)

  • [ ] Identify and describe the function of 5 major MIG system components
  • [ ] Perform the complete MIG machine setup procedure
  • [ ] Set appropriate drive roll tension for solid wire

Last Updated: 2026-03-19