⚡ 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.
Select parameters to get focus position recommendation.
| 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.
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.
Calculate W/mm² from power and spot size
M² affects focal spot size and depth of focus
Focus position affects kerf width
Optimize assist gas parameters
Estimate production time for parts
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).
Calculate power density (W/cm²) for optimal cutting performance
Estimate kerf width and path compensation for accurate part dimensions
Determine required laser power based on material and thickness
Calculate cycle time, production capacity, and time breakdown
Calculate gas consumption rates and monthly operating costs
Get optimal cutting speed for any material/power/gas combination