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Gas Flow Control in MIG and TIG Welding
Gas Flow Control in MIG and TIG Welding
Key Points
- Proper gas flow rates are essential for high-quality welds in both MIG and TIG processes
- Different materials require specific gas types and flow rates for optimal results
- Pre-flow and post-flow settings protect both the weld and equipment
- Environmental factors may require adjustments to standard flow rates
- Incorrect flow rates can lead to porosity, contamination, and excessive spatter
- Using flowmeters rather than pressure gauges ensures accurate gas delivery
MIG Welding Gas Flow Parameters
Recommended Flow Rates by Material
| Material | Flow Rate (CFH) | Recommended Gas |
|---|---|---|
| Mild Steel | 15-25 | CO₂ or 75% Argon/25% CO₂ |
| Stainless Steel | 20-30 | Tri-mix (90% He/7.5% Ar/2.5% CO₂) or 98% Ar/2% CO₂ |
| Aluminum | 25-35 | 100% Argon |
Environmental Adjustments
Indoor Settings
Standard controlled environment: 15-20 CFH
Outdoor Settings
Windy or drafty conditions: 25-30 CFH
Gas Type Factors
CO₂: 15-30 CFH
Mixed gas: 25-45 CFH
Signs of Incorrect Flow
Too low (<10 CFH): Results in porosity and weak welds
Too high (>45 CFH): Creates turbulence, drawing air into the weld pool
TIG Welding Gas Flow Parameters
Recommended Flow Rates by Material
| Material | Flow Rate (CFH) | Recommended Gas |
|---|---|---|
| Mild Steel | 15-20 | 100% Argon |
| Stainless Steel | 20-25 | 100% Argon |
| Aluminum | 20-30 | 100% Argon or Argon/Helium for thick sections |
Pre-flow and Post-flow Settings
Pre-flow
Minimum: 0.2 seconds
Recommended: 0.5-1 second
Purpose: Purges air from torch
Post-flow
Formula: 1 second per 10 amps
Example: 100A = 10 seconds
Purpose: Protects cooling weld
Cup Size Impact
Larger cups: Higher flow
Smaller cups: More efficient
Standard #7 cup: 15-20 CFH
Best Practices for Gas Flow Control
Equipment Setup
- Use flowmeters, not pressure gauges
- Check for gas leaks regularly
- Maintain proper stick-out distance
Technique Factors
- TIG: 1/8" to 1/4" tungsten extension
- MIG: 3/8" to 3/4" wire stick-out
- Maintain consistent travel speed
Quality Checks
- Inspect for porosity in welds
- Monitor tungsten condition
- Evaluate spatter levels
Troubleshooting Tips
- Porosity: Increase flow rate by 5 CFH and check for leaks
- Tungsten contamination: Extend post-flow time and verify adequate CFH
- Excessive spatter: Adjust flow to recommended range and check gas mixture