What materials cannot be cut by a fiber laser cutting machine? While fiber laser cutting machines are incredibly versatile and efficient for metal processing, their specific wavelength (typically around 1.06 μm) and high power density make them unsuitable for certain materials due to safety risks, fire hazards, or poor cutting quality.
Here are the materials that cannot or should not be cut with a fiber laser:
1. Most Non-Metallic Materials
Fiber lasers are specifically designed for metals. Non-metallic materials often do not absorb the fiber laser’s wavelength effectively, or they react dangerously to the intense heat.2
- Wood, Paper, and Cardboard: These materials are highly flammable. Instead of cutting, the fiber laser often causes these materials to catch fire or char significantly. A $CO_2$ laser is the standard choice for these.
- Acrylic and Plastics: Most plastics do not absorb fiber laser energy well. Many (like Acrylic) will melt, deform, or produce toxic fumes rather than cutting cleanly.
- Glass: Fiber lasers cannot cut glass because it is transparent to the laser’s wavelength. The beam passes straight through the glass without heating it, potentially reflecting off the machine bed and damaging the laser head.
2. High-Risk Plastics (Hazardous Fumes)
Cutting certain synthetic materials with a laser is extremely dangerous for the operator and the machine hardware.
- PVC (Polyvinyl Chloride): Never cut PVC. It releases Hydrochloric Acid and Chlorine gas when heated. These gases are highly toxic to humans and will rapidly corrode the internal components, rails, and optics of your laser machine.3
- PTFE / Teflon: Similar to PVC, heating Teflon releases toxic fluorinated gases.
- Carbon Fiber: While it can be cut, it poses a significant fire hazard and the dust produced is electrically conductive, which can short-circuit the machine’s electronic components.
3. Extremely Reflective Metals (With Caution)
Older fiber lasers struggled significantly with “Back-Reflection,” where the laser beam bounces off the shiny surface and returns into the cutting head, destroying the optics. While modern machines have protective sensors, these metals remain challenging:
- Pure Copper and Brass: These are highly reflective and thermally conductive.4 They require high power and specific “Pulsed Mode” settings to pierce safely.
- Polished Mirror-Finish Stainless Steel: The reflection can interfere with the height sensor or damage the lens if not handled with specialized “non-reflective” film or specific cutting parameters.
4. Thick Materials Exceeding Machine Power
Every fiber laser has a “Physical Limit” based on its wattage.
- If you attempt to cut material thicker than the machine’s rated capacity (e.g., trying to cut 30mm carbon steel with a 1kW laser), the laser will fail to penetrate the material. This causes molten metal to spray back (blowback), which can crack the protective lens or clog the nozzle.
Summary Table: Material Compatibility
| Material | Fiber Laser Suitability | Recommended Alternative |
| Carbon/Stainless Steel | Excellent | N/A |
| PVC | NEVER (Corrosive/Toxic) | Mechanical CNC or Waterjet |
| Wood / Acrylic | Poor (Fire/Melting) | $CO_2$ Laser |
| Glass | Impossible (Transparent) | Waterjet or Diamond Saw |
| Thick Stone/Granite | Impossible | Waterjet |