Laser cutting slices carbon steel, stainless, and aluminum with light focused sharper than a knife edge. Because the beam never dulls, edges stay crisp from the first part to the 10,000-th. This guide shows you, step by step, how to pick machines, set parameters, and check quality so your metal parts exit the bed on-size and burr-free.
Indice dei contenuti
- How laser cutting works on metal
- Select the right laser type for your job
- Know material and thickness limits
- Compare assist gases and edge quality
- Balance cutting speed, power, and cost
- Design guidelines for laser-cut metal parts
- Prevent common laser-cutting defects
- Measure accuracy and surface finish
- Safety and maintenance tips for lasers
- Budget and lead-time considerations
- Need bending & machining services?
- Summary checklist for successful metal laser cutting
How Laser Cutting Works On Metal
A power source excites a laser medium—CO2 gas, fiber-pumped Yb, or disk. Mirrors or fiber deliver the beam to a lens that focuses energy into a 100-µm spot. Assist gas blows molten metal away, leaving a kerf only 10–20 % wider than the beam. Motion controllers trace DXF or STEP outlines with ±0.05 mm repeatability.
Select The Right Laser Type For Your Job
The choice of machine changes edge color, speed, and cost. Compare options below before booking shop time.
| Laser type | Wavelength µm | Best metals | Max thickness (mild steel) | Capital cost index* |
|---|---|---|---|---|
| CO2 (DC) | 10.6 | Steel, stainless | 20 mm | 1.0 |
| Fiber 3 kW | 1.06 | Steel, Al, Cu reflective alloys | 25 mm | 1.3 |
| Fiber 6 kW+ | 1.06 | Thick steel, stainless | 40 mm | 1.6 |
| Disk 4 kW | 1.03 | High-mirror Al precise edges | 25 mm | 1.4 |
*1.0 ≈ baseline cost of a 4 kW CO2 system.
Know Material And Thickness Limits
Every metal absorbs laser energy differently. The plot shows typical maximum cut thickness at 4 kW fiber.
Mild steel ██████████████ 25 mm Stainless 304 ███████████ 20 mm Aluminum 5052 ████████ 12 mm Brass C260 ██████ 6 mm Copper C110 █████ 4 mm Titanium 6-4 ███████ 8 mm
Above these limits, kerf widens and dross builds. For thicker plates switch to plasma or oxy-fuel.
Compare Assist Gases And Edge Quality
Assist gas clears the kerf and influences oxidation. Choose with the following guide.
| Gas | Pressure bar | Edge color | Best on | Cost index* |
|---|---|---|---|---|
| O2 | 0.8–1.5 | Dark, oxidized | Steel ≤ 12 mm fast cut | 1.0 |
| N2 | 8–18 | Bright, paint-ready | Stainless, Al | 1.8 |
| Compressed air | 6–10 | Light oxide | Thin steel ≤ 3 mm budget work | 0.2 |
| Ar | 6–12 | Oxide-free | Titanium, aerospace | 3.5 |
*Cost index relative to oxygen at same flow.
Balance Cutting Speed, Power, And Cost
More watts cut faster, but electricity and optics cost more. Use this reference chart for 4 kW vs 6 kW fiber on mild steel with nitrogen assist.
Thickness mm | Speed 4 kW (m/min) | Speed 6 kW (m/min) ------------------------------------------------------ 1.0 | 45 | 62 3.0 | 12 | 20 6.0 | 4.5 | 8 10.0 | 1.5 | 3
Doubling power rarely halves cycle time on thin gauges due to machine acceleration limits. For sheet ≤ 3 mm, table swap speed often dominates ROI.
Design Guidelines For Laser-Cut Metal Parts
- Minimum slot width ≥ kerf × 1.2 (≈ 0.2 mm for fiber).
- Hole diameter ≥ thickness for clean roundness.
- Keep inner corner radius ≥ kerf to reduce dwell burn.
- Tabs for nests: 0.2 mm width keeps parts attached during shakeout.
- Leave 3 mm sheet margin to clamp fingers—avoids edge flare.
Prevent Common Laser-Cutting Defects
| Defect | Symptom | Main cause | Fast fix |
|---|---|---|---|
| Dross | Beads under edge | Low gas pressure | +2 bar N2 |
| Striations | Wavy lines | Focus off | Auto-focus –0.5 mm |
| Burn marks | Brown halo | Dirty lens | Swap protective glass |
| Edge taper | Top wider than bottom | Power too low, speed too high | -10 % speed |
Measure Accuracy And Surface Finish
Use simple tools to confirm cut quality:
- Digital caliper—Hole Ø tolerance ±0.05 mm in 3 mm steel.
- Square gauge—Edge perpendicularity ≤ 0.3 mm per 25 mm thickness.
- Surface roughness tester—Ra 3–6 µm typical for nitrogen cut stainless.
Safety And Maintenance Tips For Lasers
A Class 4 laser can blind in milliseconds. Always:
- Enclose cutting area; interlock doors to stop beam.
- Wear OD 6+ goggles when viewing open applications.
- Replace nozzle every 1 000 pierces to keep beam centric.
- Clean lens daily; 5 µm spatter spot can cost 5 % power.
Budget And Lead-Time Considerations
Laser machines save time on setup; cutting cost scales mostly with runtime and gas.
Gauge mm | Parts/hour (1 m2 nests) | Cost $/part* | Lead-time days 1–2 | 140 | 0.35 | 2 3–4 | 75 | 0.80 | 3 5–8 | 28 | 2.30 | 4 >10 | 12 | 4.20 | 5
*Medium complexity, nitrogen assist, excludes material.
Need Bending & Machining Services?
We cut steel, stainless, and aluminum on 3–12 kW fiber lasers, then bend, tap, and machine in-house for one-stop delivery. Upload your STEP file for a rapid quote.
Summary Checklist For Successful Metal Laser Cutting
- Select laser type—fiber beats CO2 for Al and Cu.
- Confirm assist gas—oxygen for speed, nitrogen for paint-ready edges.
- Use min slot ≥ 0.2 mm and hole Ø ≥ thickness.
- Start with power, speed, and gas from target thickness chart; tweak for dross-free edge.
- Inspect the first article—measure kerf, verify bend sequence, and log program revision.
With these rules you will cut clean profiles, avoid costly rework, and ship orders on time, every time.
