Shield Gas Flow Optimization for EOS M290
Shielding gas flow in PBF-LB/M is critical for ejecta removal and protecting the laser path. Poor flow near the inlet can recirculate soot/spatter, attenuate the beam, and degrade local melt pool stability and part quality. On the EOS M290, a backward-facing step between the lower inlet and the build plane is the primary driver of this recirculation.
Current practices to “tune” flow are often:
-Trial-and-error adjustments with limited diagnostics
- Hardware changes that don’t address root-cause geometry
- Expensive and slow to validate across the full plate
These challenges slow production readiness and can cause spatial variation in porosity and melt pools.
The Solution
We implemented a geometry-first fix that eliminates the step and creates a cohesive, uniform cross-flow across the plate. The validated modification set:
- Raise build platform +11 mm to align with the inlet exit plane
- Raise optics +11 mm to maintain the focal plane (no recal)
- Recess lower inlet 8 mm (flush to back wall) for added development length
- Install a height-adjustable recoater
- Raise the surrounding chamber floor to avoid edge drop-offs
What changed: MRV flow maps show the inlet-side recirculation bubble disappears; gas stays attached and uniform across the plate. Beam profiling confirms a healthy Gaussian beam before/after the optics spacer, with negligible changes in waist/position.
Key Benefits
Faster Stabilization
– Cohesive flow across the plate without ad-hoc vent tweaks.
Full Plate Consistency
– ~10% deeper melt pools near the former “bad-flow” zone and tighter CDFs across plates.
Better Density & Ductility
– ~30% fewer pores in XCT analysis; average elongation ~3.3% in tensile bars.
Low Disruption
– Optics spacing preserves beam characteristics within OEM targets