Cutting Heavy Plate: Laser, Plasma, and Gas — Capabilities, Limitations, and Applications

For years, cutting heavy plate was mainly associated with plasma and gas, while fiber lasers were considered a technology for thin and medium-thickness sheets. Today, this distinction is no longer so clear-cut—modern high-power fiber laser cutters, with configurations of up to 30 kW or 60 kW, can also be a highly efficient solution for thick materials.

However, choosing a technology is not simply a matter of which machine can cut the thickest material. Other factors that matter include cutting speed, process cost, edge quality, heat-affected zone, bevel cutting ability, and the actual cost of producing a single part. According to STIGAL’s calculations, high-power fiber laser cutting—for example, 30 kW—can be up to 2–3 times faster than plasma cutting for certain parts. You’ll make the best decision by comparing the technologies on your own parts—through testing or calculations for a specific production run.

What does “heavy plate” mean in metal cutting?

There is no single, universal threshold defining where “heavy plate” begins. For some facilities, 12–15 mm may already be considered a demanding material, while for companies in the shipbuilding, offshore, energy, construction, or machinery industries, much thicker plates are often the standard.

When selecting a technology, it is important to analyze not just the thickness, but the entire production process: the type of material, the geometry of the parts, the batch size, the expected edge quality, cutting time, the cost of process gases, the need for bevel cutting, and subsequent welding and machining. With heavy plates, productivity is particularly important—a difference of just a few minutes per part in mass production translates to many hours of savings per month. Therefore, when comparing laser, plasma, and gas cutting, one must consider not only the maximum cutting thickness but also the unit cost and the throughput of the entire process.

Laser Cutting of Heavy Plates — Not Just Accuracy, but Also Productivity

Cutting heavy plate with a fiber laser is increasingly becoming a viable alternative to plasma cutting—especially in facilities that want to increase productivity, shorten part turnaround times, and reduce the number of post-cutting operations. High-power lasers are no longer a technology reserved exclusively for high-precision parts: in 20 kW, 30 kW, or 60 kW configurations, speed is also a major advantage. With a 60 kW laser source, it is possible to laser-cut materials up to approximately 100 mm thick, although maximum thickness alone should not be the sole selection criterion.

The key benefits of cutting heavy plate with a high-power laser include high cutting speed, a smaller heat-affected zone than with many other thermal technologies, a narrower kerf, high repeatability, and the ability to reduce the need for secondary processing. Laser cutting is therefore advantageous not only when a part requires high accuracy, but also when increasing production throughput is the top priority. We discuss how to select the right laser source in our guide on how to choose the power of a fiber laser.

It is worth noting that, depending on the material, cutting thickness, or process parameters, subtle marks or micro-serrations may appear on the edge after laser cutting, resulting from the characteristics of beam guidance and molten material removal. This does not necessarily indicate a technological problem—however, it should be evaluated in light of the requirements of the specific part, as well as any subsequent machining and welding.

30 kW Laser vs. Plasma — When Does the Difference in Speed Matter?

In a manufacturing facility, what matters is not only whether the technology can handle a given thickness, but also how quickly and at what cost it can produce a specific part. According to STIGAL’s calculations, a high-power fiber laser—for example, 30 kW—can achieve cutting times that are as much as 2–3 times shorter than plasma cutting for certain parts.

This difference is particularly significant in mass production, with repetitive parts, and in situations where the machine operates for many hours a day. Faster cutting means more parts per shift, shorter order lead times, better machine utilization, and fewer bottlenecks. That is why a laser for heavy plate is worth considering not only in terms of edge quality, but also in terms of the productivity of the entire facility—a high-power laser source can significantly improve production economics.

AirCut — Compressed Air Cutting and Process Costs

One of the key factors affecting the cost-effectiveness of laser cutting is the process gas. In traditional processes, nitrogen or oxygen is used—depending on the material, thickness, and quality requirements. For thicker materials and longer processing times, the cost of the gas can account for a significant portion of the unit cost of the part.

AirCut technology —that is, cutting with compressed air—allows these costs to be reduced in many cases and makes high-power fiber lasers even more competitive compared to other cutting methods. Approximate ranges: for a laser With 12 kW, you can cut up to about 10 mm with compressed air; with 20 kW, up to about 15 mm; and with 30 kW, up to about 20 mm . These are not the maximum laser cutting thicknesses, but rather the ranges within which compressed air can be used as a low-cost process gas. The laser can still cut thicker materials, but the process requires a suitably selected gas—most often oxygen.

HQC/HD CNC plasma cutter for heavy steel plates — smooth edges and a larger heat-affected zone

Plasma cutting remains a very important technology in the processing of medium- and heavy-plate steel. A CNC plasma cutting machine is well-suited for the production of steel structures, machine components, frames, brackets, parts for heavy industry, and welded components. A properly selected process produces a smooth edge, especially when using high-quality equipment. Plasma cutting differs from laser cutting primarily in its larger heat-affected zone, wider kerf, and different thermal characteristics.

Depending on the plasma cutting system, it is possible to cut steel plates up to about 50 mm thick. However, not all plasma solutions should be lumped together—standard air cutting produces one result, while advanced HQC/HD-class systems, designed for higher-quality cuts, produce another. HQC technology uses cutting gas and shielding gas selected specifically for the material, which minimizes edge bevel, reduces roughness, and improves surface quality.

HQC/HD plasma is worth considering, especially when a facility requires smooth edges, good repeatability, scoring and dot marking, high-quality holes, a stable process for mass production, and 3D bevel cutting. However, it is important to remember that even with high-quality plasma, the heat-affected zone will typically be larger than with a laser—and fiber lasers have the advantage where minimizing thermal impact, high accuracy, or minimizing post-processing are key considerations.

Gas cutting of heavy plates — a technology for exceptionally thick materials

Gas (oxygen) cutting continues to hold a strong position when it comes to very thick carbon steel and low-alloy steel plates. It is used, among other things, in heavy industry, shipbuilding, the offshore sector, the energy sector, and the construction industry. Its greatest advantage is its ability to handle exceptionally thick carbon steel— up to approximately 320 mm.

The limitations include a slower process speed, a larger heat-affected zone, a higher risk of distortion, and less material versatility than with laser or plasma cutting. Gas cutting should therefore be viewed as a technology for specific applications, rather than the default solution for every heavy plate—it is particularly important where thicknesses are required that exceed the range of standard plasma or laser cutting in a given configuration.

Laser and gas cutting in a single machine — maximum flexibility in application ranges

Facilities that work with both heavy and exceptionally thick steel plates may consider combining fiber laser and gas cutting on a single machine. This configuration combines the advantages of both technologies without the need to set up separate workstations. The high-power laser enables fast and efficient cutting across a wide range of thicknesses (up to approx. 100 mm at 60 kW, and at lower power levels with the cost-effective AirCut), while the oxy-fuel torch allows for cutting exceptionally thick carbon steel—up to approximately 320 mm.

This allows a single facility to quickly and efficiently cut a wide range of parts with a laser, while still being able to handle projects for exceptionally thick components. This solution is particularly valuable in shipyards, the offshore industry, steel construction, the energy sector, heavy machinery manufacturing, and large metalworking facilities—it allows for an expanded range of supported thicknesses, better utilization of production space, and reduced investment in multiple separate workstations.

Laser, Plasma, or Gas — A Comparison of Technologies

This comparison is general in nature—actual differences depend on the material, thickness, machine configuration, and specific application.

FIBER Master HD — a high-power laser for large-format and demanding production applications

When working with heavy plates and large formats, it is not only the power of the laser source that matters, but also the machine’s design: gantry stability, working area, material support system, loading and unloading procedures, fume extraction, and operator safety. The FIBER Master HD is a large-format STIGAL fiber laser cutting machine designed for demanding industrial applications — for facilities that require a large working area, high laser power, and a configuration tailored to heavy, large sheets.

This machine is ideal for shipyards, the offshore industry, steel construction, the machinery industry, the energy sector, and facilities that process large-format steel plates. High laser power, combined with the right design, not only allows for cutting thicker materials but, above all, increases productivity. Depending on the configuration, it is also possible to combine laser and gas cutting technologies. Our product line also includes compact laser cutters for steel plates tailored for smaller facilities.

STIGAL Plasma-Gas Machines — Flexibility for a Range of Thicknesses

In facilities that work with a very wide range of material thicknesses, plasma cutting machines and oxy-fuel cutting machines are often good solutions. Combining plasma and gas technologies in a single machine allows for flexible selection of the process based on the material and task—plasma handles standard structural components, while the oxy-fuel torch handles the thickest carbon steel steel plates.

STIGAL plasma-gas cutting machines can be configured with high-quality HQC/HD power units, which ensure a smooth edge, good repeatability, and high process stability. They can also be equipped with bevel cutting solutions, which allow the workpiece to undergo weld preparation as early as the cutting stage.

Bevel Cutting for Edges on Heavy Plates of Steel

When working with heavy plates, it is often not only the cutting of the material that matters, but also the preparation of the edges for subsequent processes. If the part is to be welded, bevel cutting is often one of the key stages of production. Performing bevel cutting as a separate operation increases the time, cost, and number of workstations required.

That’s why it’s worth considering a machine that allows for 3D bevel cutting or beveling edges during the cutting process. Preparing edges for welding directly on the CNC machine shortens the production process and reduces the need for additional machining—this applies to both laser solutions with a 3D bevel cutting head and plasma-gas cutting machines with a 3D bevel cutting head.

How do you choose the right technology for cutting heavy plates?

When selecting a technology, it’s best to start by analyzing the actual production process. The most important questions are: what steel plate thicknesses are cut most frequently, what materials are most common, how many parts are produced per month, how many holes and contours a typical part has, whether bevel cutting is required, whether AirCut can be used, and whether the facility needs the capability to cut exceptionally thick materials.

For one facility, a high-power fiber laser will be the best choice; for another, a CNC plasma cutting machine with an HQC/HD power source; and in yet another case, a plasma-gas machine or a combination of laser and gas cutting. If you’re torn between thermal technologies, you may also find our guide “Laser or Plasma—How to Choose a Technology” and our article on how to select a CNC machine for metal cutting helpful.

The most reliable comparison is not based on general tables, but on specific details. Cutting tests or calculations based on your own parts allow you to verify the actual cutting time, the cost of producing the part, the cost of gas, edge quality, the heat-affected zone, and the cost-effectiveness of laser, HQC/HD plasma, gas, or a combined solution.

Summary — A laser for heavy plate can be a viable alternative to plasma

Cutting heavy plate doesn’t necessarily mean you have to choose plasma or gas cutting. Modern high-power fiber laser cutters also perform well in heavier industrial applications—their advantages include not only accuracy but also high speed, a smaller heat-affected zone, and greater productivity. CNC plasma cutting, especially in the HQC/HD configuration, remains a very robust technology for medium- and heavy-gauge steel plates, while gas cutting retains a strong position for exceptionally thick materials (carbon steel up to approx. 320 mm).

Combining laser and gas cutting on a single machine is a highly flexible solution. STIGAL designs and supplies CNC metal-cutting machines—high-power fiber laser cutting machines, CNC plasma cutting machines, CNC oxy-fuel cutting machines, plasma-gas solutions, and configurations that combine laser and gas cutting.

Frequently Asked Questions — Cutting Heavy Steel Plates