Shielding Gas Flow & Bottle Runtime Calculator
Calculate shielding gas flow rates (L/min, CFH), nozzle exit velocity, Reynolds number laminar flow boundaries, and high-pressure cylinder bottle autonomy for fiber laser welding.
Gas & Nozzle Configuration
Stainless Steel, Titanium, Aluminum & General Welding — Heavier than air. Blankets the molten keyhole effectively. Zero chemical reactivity with molten puddle.
Fluid Flow Regime: Turbulent Flow (Porosity Hazard!)
Excessive exit velocity creates turbulent vortex eddies that suck atmospheric air into the shield, causing black oxidation and porosity!
Fluid Dynamics & Autonomy
Shop Calibration Best Practices
- Pre-Flow Time: Set pre-flow to 0.5 - 1.0s to purge air before laser firing.
- Post-Flow Time: Keep shielding active 1.5 - 2.5s while the puddle cools below 400°C to avoid atmospheric bluing.
- Nozzle Angle: Angle gun at 10° - 15° push or pull angle. Excessive lean (> 25°) detaches the gas shield and aspirates oxygen.
Laminar Shielding vs. Turbulent Air Entrainment
1. The Danger of "More Gas is Better"
Welders often mistakenly crank gas regulators above 25 L/min when spotting oxidation. However, fluid mechanics shows that exceeding the critical Reynolds number ($Re > 2300$) converts the shielding column from laminar streamline flow into chaotic turbulent vortices:
Turbulence acts like an injector pump, dragging ambient oxygen and nitrogen directly into the boiling keyhole, creating devastating internal porosity and brittle welds.
2. Diffuser Screen Maintenance
Handheld laser welding torches contain a porous sintered metal or fine mesh diffuser behind the copper contact tip. If spatter clogs this diffuser, gas jets become non-uniform, causing immediate weld contamination even at correct flow meter readings.