Laser cutting has become a game-changer in the metal fabrication industry, offering unparalleled precision and efficiency. From automotive manufacturing to aerospace engineering, lasers enable faster production cycles, cleaner cuts, and less material waste compared to traditional cutting methods.
What type of laser is used to cut metal, and how do you decide which one is right for you? Below is an in-depth look at the most common laser types, key considerations for choosing one, and practical tips to get started.
In this article, we’ll explore how laser cutting works, compare different laser types for metal cutting, and outline the critical factors that influence your choice.
What Is Laser Cutting?
Laser cutting is a process in which a highly focused beam of light is directed onto a workpiece to melt, burn, or vaporize the material. By integrating precise motion control, the laser can trace complex shapes at high speeds and with minimal waste. This high-intensity light beam is generated by different types of lasers, each with its own set of characteristics and applications.
Why Use Lasers for Metal Cutting?
- Precision: Lasers produce cleaner and more accurate cuts than many mechanical methods.
- Speed: Industrial laser cutters often operate faster than traditional tools, especially on thinner metals.
- Versatility: A single laser cutter can handle multiple metal types and thicknesses.
- Low Material Waste: The contactless nature of laser cutting reduces the chance of warping or damage to the surrounding material.
Common Laser Types for Metal Cutting
While there are several types of lasers on the market, three are most commonly employed for metal cutting: CO₂ lasers, fiber lasers, and Nd:YAG lasers. Each has its own strengths and weaknesses.
1.CO₂ Lasers
- How They Work: CO₂ lasers use a gas mixture (primarily carbon dioxide) excited by an electrical current to produce a concentrated infrared beam.
- Advantages:
- Proven technology with a long track record in industrial settings.
- Capable of cutting thicker metals, especially mild and stainless steel.
- Limitations:
- Relatively high maintenance costs due to mirror alignments and gas refills.
- Less efficient on thinner metals compared to newer fiber lasers.
2. Fiber Lasers
- How They Work: Fiber lasers use a seed laser amplified in glass fiber, producing a beam with a shorter wavelength than CO₂.
- Advantages:
- Higher energy efficiency, resulting in lower operational costs.
- Faster cutting speed on thin metals (e.g., stainless steel, aluminum).
- Excellent for cutting reflective metals (e.g., copper, brass) without the risk of beam reflection damage.
- Limitations:
- Higher upfront cost.
- Specialized maintenance and potential repair expenses.
3. Nd:YAG (Neodymium-Doped Yttrium Aluminum Garnet) Lasers
- How They Work: Nd:YAG lasers use a crystal as the lasing medium, generating a beam that can be pulsed or continuous.
- Advantages:
- High peak power, which is useful for precision drilling, engraving, or spot welding.
- Limitations:
- Not as energy-efficient as fiber lasers.
- Less commonly used for large-scale metal cutting due to higher overall costs and complexities.
4. Diode Lasers (Optional Discussion)
- How They Work: Semiconductor-based technology that converts electrical energy directly into light.
- Advantages:
- Compact and typically lower on energy consumption.
- Limitations:
- Generally lower power outputs, thus less suitable for heavy industrial metal cutting applications.
Factors to Consider When Choosing a Laser
Material Type and Thickness
- Metal Variety: Different metals (e.g., aluminum, stainless steel, copper) require different laser power and wavelengths. For instance, reflective metals are best handled by fiber lasers.
- Thickness: Thicker plates often need higher wattage. CO₂ lasers are traditionally preferred for heavy metals, but high-powered fiber lasers are increasingly used for thick applications.
Production Volume and Speed
- High-Volume Operations: If your factory runs continuous production, fiber lasers might be more cost-effective in the long run due to faster cutting speeds on thin materials.
- Small-Scale or Job Shops: If you’re not dealing with massive production runs, a CO₂ laser could be more budget-friendly in terms of initial investment.
Cost and Budget
- Initial Investment: Fiber lasers can be more expensive upfront but offer lower operating costs. CO₂ lasers are cheaper to purchase but can be costlier to maintain.
- Long-Term Operational Costs: Include factors such as electricity, cooling, maintenance, and consumables (e.g., gas lenses).
Cut Quality Requirements
- Edge Finishes: Consider how much post-processing might be required. Laser cutting often eliminates or reduces the need for deburring and polishing.
- Precision: For extremely fine or intricate cuts, check the laser’s beam quality and stability.
Maintenance and Safety
Laser Maintenance
- Lens Cleaning and Beam Alignment: Dirty lenses or misalignment can degrade cut quality and reduce power.
- Cooling Systems: Proper cooling ensures stability and longevity.
- Scheduled Upkeep: Fiber lasers generally require less maintenance, while CO₂ lasers may need more frequent part replacements.
Workplace Safety
- Protective Eyewear: Laser beams, even reflections, can harm your eyesight. Always use proper shielding.
- Ventilation: Laser cutting can produce harmful fumes and particulates, so ensure adequate exhaust systems.
- Enclosures and Interlocks: Industrial laser systems often come with protective enclosures to prevent accidental exposure.
Classification of 3 Kinds of Laser Cutting Mechanism
According to its mechanism, laser cut mechanism can be divided into vaporization cutting, melting cutting, laser oxygen-assisted melting cutting, and controlled fracture cutting.
(1) Vaporized cutting
The parts are rapidly heated to the boiling point under the action of the laser, part of the material turns into steam and escapes, and part of the material is blown away from the cutting part as a jet. The laser power density required for this cutting mechanism is generally about 1W/cm2, which is a cutting method without melting materials (wood, graphite, plastic, etc.).
(2) Melt cutting
The laser heats the workpiece to a molten state, and the auxiliary gas flow of argon, helium, nitrogen, etc. coaxial with the beam blows the molten material away from the slit. The laser power density required for melting and cutting is generally about 10W/cm2.
(3) Oxygen-assisted melting and cutting
This method is mainly used for cutting metal materials. The metal is quickly heated by the laser to above the ignition point, and it undergoes a violent oxidation reaction (ie combustion) with oxygen, releasing a lot of heat; continue to heat the next layer of metal, the metal will continue to be oxidized, and the oxide will be blown from the slit with the help of gas pressure Drop. The cutting process can be attributed to repeated preheating→combustion→slag removal. To realize laser oxygen-assisted melting and cutting, the following processing conditions must be met.
① The ignition point of the cut metal is lower than its melting point.
For example, the ignition point of iron is 1350°C, which is 1500°C lower than its melting point.
②The melting point of the generated slag should be lower than the melting point of the metal.
For example, the melting point of iron slag is 1300~1500°C.
③The combustion can release a lot of heat.
For example, the reaction formula of iron when cutting is
Fe+0.50,–Fe0+64. 3 cal/mol
2Fe+l 502 -+Fe, 0, +198.5 cal/mol
3Fe+20, -Fe, 0,+266.9 cal/mol
When oxygen helps to melt and cut steel, the heat energy released by combustion in oxygen accounts for 60% of the total energy. The energy required for oxygen-assisted melting and cutting is 5% of that of vaporized cutting. It can be seen that the laser oxygen-assisted melting and cutting is mainly carried out by using the heat released by the oxidation of steel and other metals in the cutting process.
Conclusion
When choosing the best laser for metal cutting, balance your upfront investment, long-term operating costs, production volume, and required cut quality. By understanding the strengths and limitations of each laser type, you can make an informed decision that aligns with your business goals and technical needs.
FAQ
Can a diode laser cut metal?
While diode lasers can cut certain thin metals, they often lack the power required for heavy-duty industrial applications. They are more common in engraving or light fabrication tasks.
How thick can a laser cut?
Thickness capabilities vary significantly by laser power and type. CO₂ lasers can handle up to about 20–25 mm of mild steel, while high-powered fiber lasers can exceed that range, depending on the wattage.
Which laser is best for reflective metals like aluminum or brass?
Fiber lasers typically handle reflective metals better than CO₂ lasers, reducing the risk of back-reflections that can damage the laser source.
Is laser cutting more expensive than traditional methods?
The initial investment for a laser cutter can be higher than for traditional mechanical tools. However, faster cutting speeds, lower waste, and reduced need for post-processing often balance or offset the costs over time.
