Student Material 001: MIG Welding Parameter Chart & Troubleshooting Guide

Material ID: U6M2-MAT-001 Purpose: Quick reference for MIG welding parameters, machine setup, and problem diagnosis Updated: 2026-03-19

MIG Parameter Chart — Mild Steel, ER70S-6, C25 Gas

Thickness	Wire	WFS (IPM)	Voltage	Gas (CFH)	Transfer
24 ga (0.024")	0.023"	100-150	15-16	20	Short circuit
20 ga (0.036")	0.023"	150-200	16-17	20	Short circuit
18 ga (0.048")	0.030"	150-250	17-18	20-22	Short circuit
16 ga (0.060")	0.030"	200-300	17-19	20-22	Short circuit
14 ga (0.075")	0.030"	250-350	18-20	22	Short circuit
12 ga (0.105")	0.030"	300-400	19-21	22	Short circuit
⅛" (0.125")	0.035"	250-400	19-22	22-25	Short circuit
3/16"	0.035"	350-500	21-24	22-25	SC/Spray
¼"	0.035"	400-600	23-26	25	Spray
⅜"	0.045"	300-500	24-28	25-30	Spray

Torch Angle Quick Reference

BUTT JOINT (flat):        T-JOINT FILLET:          LAP JOINT:
     torch                     torch                   torch
      │ 10° push                │↗ 45°                  │↗ 60-70°
      │/                        │                       │
  ═══════════              ─────┼─────              ═══════════
                                │                   ───────────
                           ─────────────

Work angle: 90°           Work angle: 45°          Work angle: 60-70°
Travel angle: 10° push    Travel angle: 10° push   (angled toward bottom plate)

MIG Sound Reference

Sound	Description	Diagnosis
Steady "bacon frying"	Consistent sizzle with regular rhythm	CORRECT — good short-circuit transfer
Harsh crackling/popping	Erratic, loud pops	Voltage TOO LOW — increase 1-2V
Smooth humming	Quiet, lazy arc	Voltage TOO HIGH — decrease 1-2V
Aggressive roar	Very loud, forceful	WFS TOO HIGH — reduce wire feed
Intermittent pops/silence	Arc starts and stops	WFS TOO LOW — increase wire feed

MIG Troubleshooting Flowchart

PROBLEM?
│
├── Excessive Spatter
│   ├── Check polarity (must be DCEP for solid wire)
│   ├── ↑ Voltage 1-2V
│   └── Clean nozzle of spatter buildup
│
├── Porosity (holes in weld)
│   ├── Check gas flow (20-25 CFH)
│   ├── Block drafts/wind
│   ├── Clean base metal (grind to bright, degrease)
│   ├── Replace gas hose if cracked
│   └── Check for empty cylinder
│
├── Burn-Through
│   ├── ↓ Wire feed speed
│   ├── ↓ Voltage
│   ├── ↑ Travel speed
│   └── Use pulsing technique on thin material
│
├── Cold/Tall/Unfused Bead
│   ├── ↑ Wire feed speed (more amps)
│   ├── ↑ Voltage
│   ├── ↓ Travel speed
│   └── Direct arc into root of joint
│
├── Wire Won't Feed
│   ├── Check for bird's nest at drive rolls
│   ├── Check for blocked contact tip
│   ├── Check liner for kinks or wear
│   ├── Verify correct drive roll tension
│   └── Straighten gun cable
│
├── Wire Burns Back to Tip
│   ├── ↑ Wire feed speed
│   ├── Replace contact tip (worn/fused)
│   └── Check for too much CTWD
│
└── Arc Won't Start
    ├── Check work clamp connection
    ├── Verify wire extends past nozzle
    ├── Check power switch and trigger
    └── Check for blown fuse/tripped breaker

Machine Setup Checklist

WIRE SYSTEM:
[ ] Correct wire type and diameter on spool
[ ] Wire threaded through drive rolls correctly
[ ] Drive roll tension: wire slips against solid surface (not too tight)
[ ] Contact tip matches wire diameter
[ ] Wire trimmed to ⅜" past nozzle

GAS SYSTEM:
[ ] Correct gas type (C25 for steel, Ar for Al/SS)
[ ] Cylinder valve open
[ ] Regulator set: _____ CFH (20-25 typical)
[ ] Gas flow verified at nozzle (press trigger briefly)

MACHINE SETTINGS:
[ ] Polarity: DCEP (for solid wire)
[ ] Voltage: _____ V
[ ] Wire feed speed: _____ IPM

PHYSICAL SETUP:
[ ] Work clamp on workpiece (clean metal contact)
[ ] Nozzle clean of spatter
[ ] Gun cable not kinked or tightly coiled
[ ] Joint surfaces ground to bright metal
[ ] Ventilation/fume extractor positioned

SAFETY:
[ ] Full PPE on
[ ] Fire extinguisher within 15 feet
[ ] Welding screens deployed
[ ] Combustibles cleared (35-foot radius)

CTWD (Stickout) Reference

TOO SHORT (< ¼")         CORRECT (⅜" - ½")        TOO LONG (> ¾")
┌────────┐               ┌────────┐               ┌────────┐
│ Nozzle │               │ Nozzle │               │ Nozzle │
│  ──┐   │               │  ──┐   │               │  ──┐   │
│    │tip│               │    │tip│               │    │tip│
│    └───│               │    └───│               │    └───│
│     ·  │←too close     │        │               │        │
└────────┘               │     ·  │←correct       │        │
═════════                └────────┘               │        │
                         ═════════                │     ·  │←too far
                                                  └────────┘
                                                  ═════════

Results:                 Results:                 Results:
- Too much current       - Stable arc             - Low current
- Risk of tip damage     - Good penetration       - Unstable arc
- Wire may fuse to tip   - Proper shielding       - Poor shielding

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Last Updated: 2026-03-19