Slide 003: MIG Parameter Selection & Troubleshooting

Slide Visual

Slide Overview

This slide provides the parameter selection guidelines for MIG welding various thicknesses of mild steel and a systematic troubleshooting approach for common MIG welding problems.

Instruction Notes

Parameter Selection — Mild Steel with ER70S-6 and C25 Gas

Thickness	Wire Dia.	WFS (IPM)	Voltage	Approx. Amps	Transfer Mode
24 ga (0.024")	0.023"	100-150	15-16V	30-50A	Short circuit
20 ga (0.036")	0.023"	150-200	16-17V	40-60A	Short circuit
18 ga (0.048")	0.030"	150-250	17-18V	50-80A	Short circuit
16 ga (0.060")	0.030"	200-300	17-19V	70-100A	Short circuit
14 ga (0.075")	0.030"	250-350	18-20V	90-120A	Short circuit
12 ga (0.105")	0.030"	300-400	19-21V	110-140A	Short circuit
⅛" (0.125")	0.035"	250-400	19-22V	120-160A	Short circuit
3/16" (0.1875")	0.035"	350-500	21-24V	150-200A	Short circuit/spray
¼" (0.250")	0.035"	400-600	23-26V	180-250A	Spray

Note: These are starting values. Adjust based on the specific machine, joint type, and position.

The Sound of a Good Weld

MIG welding has a distinctive audio signature: - Correct settings: Steady, consistent "bacon frying" or "buzzing" sound — regular short-circuit cycling - Voltage too low: Harsh, sputtering, erratic crackling — excessive spatter - Voltage too high: Smooth humming but lazy arc, wide flat bead, potential burn-through - Wire feed too fast: Aggressive, loud crackling, wire pushing into pool aggressively - Wire feed too slow: Arc pops and sputters, wire burns back to contact tip

Systematic Troubleshooting

Problem → Most Likely Cause → Fix

Problem	Sound	Visual	Fix
Excessive spatter	Harsh sputtering	Spatter balls around weld	↑ Voltage 1-2V; check polarity; clean nozzle
Porosity	Normal sound	Holes in weld surface	Check gas flow (20-25 CFH); block drafts; clean metal
Burn-through	Loud, aggressive	Holes melted through	↓ Wire feed speed; ↓ voltage; ↑ travel speed
Cold/ropy bead	Quiet, intermittent	Tall, narrow, unfused bead	↑ Wire feed speed; ↑ voltage; ↓ travel speed
Undercut	Sizzling at edges	Groove at weld toe	↓ Voltage; ↓ travel speed; adjust torch angle
Wire burnback	Pop/crackle, arc stops	Wire fused to contact tip	↑ Wire feed speed; replace contact tip
Bird-nesting	Motor strains, no feed	Wire tangled at drive rolls	Clear nest; check tip/liner; reduce drive tension
Inconsistent bead	Varying sound	Width/height varies	Stabilize travel speed; brace arms; practice

Fine-Tuning Protocol

1. Start with recommended parameters from the chart
2. Run a 3" test bead on scrap of the same thickness
3. Evaluate: penetration (check backside if possible), bead profile, spatter, sound
4. Adjust ONE parameter at a time:
5. Spatter → adjust voltage first
6. Penetration → adjust wire feed speed
7. Bead shape → adjust travel speed and torch angle
8. Run another test bead
9. Repeat until satisfied, then weld the actual joint

Key Talking Points

1. Start with the chart, then fine-tune by sound and bead appearance
2. Adjust ONE variable at a time — never change voltage and wire feed simultaneously
3. The sound of the arc is your best real-time feedback tool
4. Most MIG problems are either voltage/WFS imbalance or gas/contamination issues
5. A 3" test bead on scrap takes 10 seconds and prevents ruining your actual part

Learning Objectives (Concept Check)

• [ ] Select starting parameters for 3 different material thicknesses
• [ ] Identify correct MIG welding arc sound vs. incorrect
• [ ] Diagnose and correct 3 common MIG welding problems

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Last Updated: 2026-03-19