Laser Focus Position Calculator
⚡ Quick Answer: Focus Position Rules
Thin (<3mm): Surface / -0.5mm | Medium (3-10mm): -10% to -25% depth | Thick (>10mm): -15% to -33% depth
Calculate the optimal focus position for laser cutting based on material type, thickness, and assist gas. Focus position significantly affects cut quality, edge roughness, and dross formation.
Recommended Focus
Select parameters to get focus position recommendation.
Focus Position Quick Reference
| Material | Gas | 1-3mm | 4-8mm | 10-20mm |
|---|---|---|---|---|
| Mild Steel | O₂ | 0 to -0.5mm | -0.5 to -1mm | -1 to -3mm |
| Mild Steel | N₂ | -0.5 to -1mm | -2 to -3mm | -3 to -5mm |
| Stainless Steel | N₂ | -1mm | -2 to -4mm | -4 to -6mm |
| Aluminum | N₂ | -1 to -2mm | -3 to -5mm | -5 to -8mm |
Negative values = focus below material surface. Values are starting points - optimize based on cut quality inspection.
Frequently Asked Questions
For cutting, focus is typically placed INSIDE the material (negative focus position). Thin materials (<3mm): focus near surface. Medium thickness (3-10mm): focus at 10-25% depth. Thick materials (>10mm): focus at 15-33% depth. This ensures the beam energy is concentrated where the cutting action occurs, improving cut quality and speed.
Related Calculators
Power Density Calculator
Calculate W/mm² from power and spot size
Beam Quality Analyzer
M² affects focal spot size and depth of focus
Kerf Width Calculator
Focus position affects kerf width
Gas Flow Calculator
Optimize assist gas parameters
Cutting Time Calculator
Estimate production time for parts
Focus Optimization Guide
In-depth focus position theory
Note: Focus positions are starting recommendations based on industry practices. Actual optimal settings vary by machine, lens, and specific material batch. Always verify by inspecting cut edges and adjusting in small increments (±0.25-0.5mm).