Complete Guide to Laser Cutting Thickness: Materials, Power & Speed Explained

Laser cutting machine is one of the most widely used manufacturing processes in modern metal fabrication. From automotive parts and industrial machinery to architectural structures and precision components, laser cutting delivers unmatched accuracy, speed, and clean edges.

But one of the most common questions manufacturers ask is:

How thick can a laser cutter cut?

The answer depends on several key factors, including the material type, laser power, cutting speed, assist gas, and machine configuration.In this complete guide to laser cutting machine

thickness, we’ll break down everything you need to know about laser cutting thickness, power requirements, and how to achieve the best cutting results.

What Does Laser Cutting Thickness Mean?

Laser cutting thickness refers to the maximum material depth a laser machine can cut through cleanly and consistently. It’s important to understand:

Cutting thickness is different from engraving depth
Thicker materials require higher laser power
The cutting limit depends heavily on material properties

For example, a fiber laser may cut 20mm mild steel easily, but struggle with much thinner copper due to reflectivity.

Key Factors That Affect Laser Cutting Thickness

Laser cutting performance is influenced by several technical factors. Let’s explore them one by one.

1. Laser Power (Wattage)

Laser power is the most direct factor affecting cutting thickness. Higher wattage lasers deliver more energy into the material, allowing deeper cuts.

Typical industrial fiber laser power ranges:

1kW – 3kW (thin to medium metals)
6kW – 12kW (thicker industrial plates)
20kW+ (heavy-duty structural cutting)

Example:

2kW fiber laser → cuts ~6mm mild steel
6kW fiber laser → cuts ~20mm mild steel
12kW fiber laser → cuts 30mm+ steel

2. Material Type

Different materials react differently to laser energy.

Key material properties include:

Melting point
Reflectivity
Thermal conductivity
Density

Metals require higher power and assist gas for efficient cutting.

Copper and aluminum are harder to cut due to reflection, while mild steel is easier.

3. Cutting Speed

Cutting speed determines how long the laser beam stays on a specific point.

Faster speed → cleaner edges, less heat distortion
Slower speed → deeper cuts, but risk of burning or dross

Finding the right balance is essential for thick cutting.

4. Assist Gas (Oxygen, Nitrogen, Air)

Assist gas improves cutting efficiency by removing molten material.

Common gases include:

Oxygen (O₂)

Best for thick mild steel
Supports combustion and increases cutting speed
Leaves an oxidized edge

Nitrogen (N₂)

Best for stainless steel
Produces clean, bright edges
Higher operating cost

Compressed Air

Low-cost option
Works for thin sheet cutting

5. Beam Quality & Focus Lens

Laser cutting thickness also depends on:

Spot size
Beam quality (M² factor)
Correct focal positioning

A well-focused beam produces:

Narrow kerf width
Higher energy concentration
Better thick-cut penetration

Maximum Laser Cutting Thickness by Material

Below is a general guide for industrial fiber lasers:

Mild Steel (Carbon Steel)

Mild steel is the easiest metal to laser cut.

Laser Power	Max Thickness
1kW	3–5mm
3kW	10–12mm
6kW	20–22mm
12kW	30–35mm

Best assist gas: Oxygen

Stainless Steel

Stainless steel requires nitrogen for clean edges.

Laser Power	Max Thickness
1kW	2–4mm
3kW	8–10mm
6kW	15–18mm
12kW	25mm+

Best assist gas: Nitrogen

Aluminum

Aluminum is reflective and needs higher power.

Laser Power	Max Thickness
3kW	6–8mm
6kW	12–15mm
12kW	20mm+

Best assist gas: Nitrogen

Copper & Brass

These are among the most difficult metals due to reflectivity.

Requires specialized fiber laser systems
Thickness limits are lower compared to steel

Typical cutting range:

1–6mm depending on machine design

Laser Type Comparison: Thickness Capability

Choosing the right laser system is critical for industrial cutting.

Fiber Laser

Fiber laser cutting in modern metal fabrication is widely preferred due to its high precision, faster processing speed, low maintenance, and excellent performance when cutting thick metals like steel, stainless steel, and aluminum in industrial applications.

Advantages of fiber laser:

High speed
Thick cutting ability
Low maintenance

Used for:

Steel plates
Stainless steel
Industrial fabrication

Common Problems When Cutting Thick Materials

Cutting thicker metals introduces challenges such as:

Excessive dross buildup
Rough edge finish
Incomplete penetration
Heat distortion and warping
Slower production speed

Proper settings and equipment help overcome these issues.

Tips to Improve Thick Laser Cutting Performance

Here are proven strategies:

Use higher assist gas pressure
Optimize cutting speed and focus
Keep nozzles aligned properly
Choose the correct lens for thick cutting
Maintain stable beam quality
Upgrade to higher wattage if needed

Industrial Applications of Thick Laser Cutting

Thick plate laser cutting is widely used in:

Structural steel fabrication
Automotive chassis manufacturing
Heavy machinery parts
Shipbuilding and offshore projects
Power plant equipment

How to Choose the Right Laser Cutting Machine

Before investing, ask:

What maximum thickness do you need to cut?
Which materials are most common?
Do you need clean edges (nitrogen cutting)?
What production speed is required?
What level of automation is needed?

Choosing the right machine ensures better ROI and long-term productivity.

Conclusion

Laser cutting thickness depends on a combination of:

Laser power
Material type
Cutting speed
Assist gas
Beam quality and focus

For manufacturers cutting thick industrial plates, high-power fiber lasers deliver the best results. If you’re planning a fabrication setup or need expert guidance on industrial cutting solutions, working with experienced engineering partners is key.