What Thickness Can a Fibre Laser Cutting Machine Cut?

Modern fibre lasers can cut far more than many buyers expect

One of the first questions we’re asked is how thick a fibre laser can actually cut.

There isn’t a single answer because cutting capacity depends on far more than laser power alone. Material type, assist gas, required edge quality and production speed all affect the practical cutting thickness.

A machine may technically cut a particular thickness, but that doesn’t always mean it’s the most efficient way to process material every day.

Understanding the difference between maximum capability and recommended production capacity helps ensure you invest in a machine that suits your workload rather than simply buying the highest-powered laser available.

What determines the maximum cutting thickness?

Laser power is only one part of the equation.

Several factors determine how effectively a fibre laser cuts thicker materials.

Laser power

Higher-powered machines generate more energy, allowing them to cut thicker material while maintaining cutting speed.

For example, a 12kW fibre laser will process thicker plate considerably faster than a 3kW machine, but that doesn’t automatically make it the better investment. If most of your production is cutting 3mm mild steel, the additional capital cost may never be recovered.

Material type

Different metals behave very differently during laser cutting.

Mild steel is generally the easiest material to process at greater thicknesses, while aluminium, copper and brass reflect more laser energy and conduct heat much more quickly. These materials often require greater laser power to achieve similar cutting performance.

Assist gas

The choice of assist gas has a significant effect on cutting performance.

Nitrogen is commonly used where a clean, oxide-free edge is required, particularly on stainless steel and aluminium. Oxygen is often used when cutting thicker mild steel because it assists the cutting process, allowing greater thicknesses to be processed efficiently.

Edge quality

Maximum thickness figures quoted by manufacturers are often based on achieving a successful cut.

Production requirements are usually different.

Many manufacturers require clean edges with minimal dross, accurate dimensions and consistent repeatability. In practice, this often means operating comfortably below the machine’s absolute cutting limit.

Typical fibre laser cutting thickness guide

The figures below are intended as a general guide. Actual cutting capacities vary depending on the machine manufacturer, laser source, cutting head, assist gas and material quality.

These figures should always be considered alongside the required cutting speed, edge finish and daily production volumes.

Mild steel

Mild steel remains the most common material processed on fibre laser cutting machines.

Modern systems produce excellent cut quality across a wide range of thicknesses, making them suitable for everything from light fabrication through to heavy engineering.

Although thicker sections can be processed, many manufacturers spend the majority of their production time cutting material between 1mm and 10mm. In these applications, cutting speed often has a greater impact on productivity than maximum cutting thickness.

Stainless steel

Stainless steel requires different cutting parameters and is typically processed using nitrogen to produce a bright, oxide-free edge suitable for fabrication, welding and finishing.

Higher-powered fibre lasers maintain excellent cut quality across thicker stainless sections while reducing processing times compared with lower-powered machines.

For manufacturers producing large volumes of stainless components, laser power should be considered alongside productivity rather than simply maximum cutting capacity.

Aluminium

Aluminium conducts heat rapidly and reflects laser energy more readily than mild steel.

Although modern fibre lasers have significantly improved aluminium cutting performance, the process demands accurate machine setup, good beam quality and correctly adjusted cutting parameters.

Manufacturers regularly processing thicker aluminium should ensure the selected machine has sufficient power to maintain both speed and edge quality.

Copper and brass

Copper and brass have traditionally been regarded as difficult materials for laser cutting because of their reflective properties.

Advances in fibre laser technology have made both materials much more practical to process, provided the machine is correctly specified.

Material thickness, surface condition and laser source all influence the final result, so applications involving these materials should always be discussed before selecting a machine.

Maximum cutting thickness isn’t always the best buying guide

One of the biggest misconceptions is that buying the most powerful laser automatically provides the best value.

In reality, it often increases capital cost, operating costs and power consumption without improving day-to-day production.

If your workload consists mainly of 2mm to 8mm mild steel, investing in a machine capable of routinely cutting 40mm plate may offer little commercial benefit.

Selecting a machine around the materials you process every day generally delivers a better return on investment than buying purely on maximum specification.

Should you buy a more powerful machine for future growth?

Future expansion is worth considering, but it should be based on realistic production plans rather than possibility.

If new contracts are likely to involve thicker materials or increased production volumes, investing in additional laser power now may avoid replacing the machine later.

If those opportunities are uncertain, purchasing a machine that suits today’s workload often provides the stronger financial case.

This is one of the reasons we spend time understanding the type of work our customers carry out before recommending a particular machine.

Choosing the right fibre laser cutting machine

Maximum cutting thickness is only one part of selecting the right machine.

Production volume, material type, sheet size, automation requirements, running costs and future growth should all be considered before making an investment.

If you’re comparing different fibre laser cutting machines, our guide on How to Choose the Right Fibre Laser Cutting Machine explains the wider factors that influence machine selection, while our comparison of 3kW vs 6kW vs 12kW Fibre Lasers looks at how power affects productivity, running costs and cutting performance.

Frequently Asked Questions

Can a 3kW fibre laser cut 20mm mild steel?

Many modern 3kW machines are capable of cutting up to around 20mm mild steel under the right conditions, although cutting speed and edge quality will be significantly lower than a higher-powered machine.

Does higher laser power always mean faster cutting?

Generally yes, particularly on thicker materials. However, the difference becomes less significant on thinner sheet where machine acceleration, motion control and overall system design also influence productivity.

Is stainless steel more difficult to cut than mild steel?

Stainless steel requires different cutting parameters and is commonly processed with nitrogen to produce a clean, oxide-free edge. Modern fibre lasers cut stainless extremely well when correctly configured.

Can fibre lasers cut aluminium?

Yes. Modern fibre laser cutting machines are widely used for aluminium, although cutting performance depends on material thickness, machine specification and correct setup.

Should I buy the highest-powered machine available?

Not necessarily. The best investment is usually the machine that matches the materials, thicknesses and production volumes you process every day, rather than simply offering the highest maximum cutting capacity.