Laser or Plasma — A Guide to Choosing Metal Cutting Technologies

Laser or plasma? This is one of the most common questions when choosing a CNC machine for metal cutting—but the answer isn’t simply which technology is “better.” Both fiber laser cutting machines and plasma cutting machines provide a stable, repeatable industrial process. They differ in edge quality, heat affect zone, hole-making capabilities, and cost for specific applications.

The technology should be selected based on the part, the material, and the entire production process, not solely on the steel plate thickness. Factors such as the type and thickness of the material, hole diameters, required edge perpendicularity, permissible bevel, thermal effects, and subsequent production steps—such as tapping, welding, bending, or preparing edges for welding—are all important. It is also worth noting that the development of fiber lasers means they are increasingly replacing smaller plasma cutting machines—thanks to their growing cost-effectiveness, the versatility of the process, and the quality of the parts.

Laser or Plasma — Key Differences in Production

This table is for illustrative purposes only—the final choice of technology depends on a comprehensive analysis of the production process.

How do lasers and plasma work?

Laser and plasma are two metal-cutting technologies that use heat, differing in the way energy is delivered to the material. A fiber laser cutting machine uses a concentrated beam of light, while a CNC plasma cutting machine uses a plasma arc that melts the metal and blows it out of the cut gap with a stream of gas. The most important differences between laser and plasma cutting therefore relate to the kerf width, the appearance of the edges, the heat-affected zone, the ability to make holes, and the cost of the process.

Therefore, the choice between a laser cutter and a plasma cutter should not be based solely on sheet metal thickness. It is much more important to consider what part is to be produced, how it will be used later, and which edge characteristics are truly essential for the subsequent process.

Laser Cutting — Technology Overview

Laser cutting provides high dimensional accuracy, good repeatability, and full control over the part’s geometry. A metal-cutting laser (fiber laser cutter) cuts structural steel, stainless steel, aluminium, and other metals—depending on the power of the laser source and the process gas—and in many applications also uses air, which reduces costs.

Laser cutting is particularly well-suited for parts with a large number of holes, small radii, and repetitive shapes—such as assembly components, parts for tapping, or components for welding. Its key advantage is the ability to cut a hole with a diameter smaller than the thickness of the steel plate (e.g., Ø3 mm in a 15 mm steel plate), ready for tapping or assembly. It also ensures greater edge perpendicularity, which is essential for fitted and bolted components. For thin and medium-gauge steel plates, a sheet metal laser cutter is particularly advantageous.

Plasma Cutting — Characteristics and Applications

Plasma cutting is a proven CNC technology for cutting electrically conductive metals—structural steel, stainless steel, and aluminium. When the parameters are properly selected, plasma cutting of steel plates and sheet metal produces a smooth edge that is ready for further production stages. A characteristic feature of plasma cutting is a slight bevel on the edges, which is fully acceptable for most structural and welded components. Holes are designed differently here than with a laser: their diameter should be close to the steel plate thickness or approximately 1.5 times the thickness (e.g., ~Ø30 mm for 20 mm steel plate). For thicker materials, plasma cutting remains very cost-competitive—and STIGAL machines with an oxygen cutting torch can cut steel up to 320 mm thick.

CNC plasma cutting is most commonly used in:

• steel structures — gusset plates, brackets, ribs, bases, and load-bearing elements,
• the machinery industry — frames, housings, covers, and mounting parts,
• manufacturing of agricultural and industrial machinery — structural parts and welded components,
• shipyards and large-scale manufacturing — sheet metal and ribs prepared for welding,
• Energy and Infrastructure — Frames, Bases, Mounts, and Support Components.

The Thermal Effects of Lasers and Plasma on Metal

Both technologies heat the material locally, creating a heat-affected zone—but the width of this zone differs. With a laser, the energy is highly concentrated, so the heat-affected zone is narrower; this is important for thin bridges, precise contours, and components prone to deformation. Plasma affects a wider area, which is a natural characteristic of the arc—with properly selected parameters, it still produces a stable, smooth cut. The heat-affected zone also depends on the material, cutting thickness, cutting speed, number of passes, and how the workpiece is supported.

Thickness, size, and cost—why shouldn’t you simplify your choice?

The common simplification that “lasers are for thin materials and plasma is for thick ones” does not reflect the realities of production. A fiber laser with sufficient power can also cut thick sheet metal (up to 50 mm), and large-format laser machines process large workpieces—the size of the workpiece alone does not determine the technology. However, the power of the source, the machine configuration, and the power supply must be taken into account.

The cost of cutting does not depend solely on the price of the machine: energy, process gases, materials, cutting speed, the number of cuts, and whether the workpiece moves directly to the next stage after cutting all play a role. Laser cutting is often the most cost-effective for parts with many holes and repeatable runs (especially with air cutting), while plasma cutting is best when the edge quality and hole proportions meet the part’s requirements. The most reliable decision is based on real data, which is why at STIGAL we conduct tests on our customers’ parts and compare the cost of the process for a specific production run.

Sample Cost Calculation for Cutting — Laser vs. Plasma

Below is a real-world comparison of the cost and time required to cut the same part ( 5 mm steel plate) using three different technologies. Here you can see why, for thin and medium-thickness steel plates, fiber laser cutting with air assist (AIR CUT) is increasingly outperforming plasma cutting—it is several times faster and the least expensive per plate.

Sample data (part test for the boiler manufacturing industry, 5 mm steel plate). The actual cost depends on the part, material, process parameters, and utility prices.

The cost of laser cutting includes: the machine’s power consumption, the laser source, the laser cooler, the exhaust fan, the compressor, and the cost of gas for O2 CUT and N2 CUT technologies.

The cost of plasma cutting includes: the power consumption of the machine, the plasma power supply, the exhaust fan, and the compressor.

When to use a laser, and when to use plasma?

Consider a CNC fiber laser cutter when the following factors are important:

• high accuracy and edge perpendicularity, as well as part repeatability,
• small holes relative to the thickness of the steel plate, including holes for tapping,
• complex shapes, a narrow cutting gap, and limited heat affect,
• mass production or small-batch production, including large formats,
• cutting thicker materials with sufficient power and energy capacity.

Consider a CNC plasma cutter when the following factors are important:

• cutting of electrically conductive metals—structural steel, stainless steel, and aluminium,
• structural and welded components: brackets, ribs, frames, base plates, mounting plates,
• a smooth edge with an acceptable, slight bevel,
• holes with diameters consistent with the capabilities of plasma technology,
• a good balance between the cost of the process and the requirements of the part.

How does STIGAL help you choose the right cutting technology?

STIGAL designs and manufactures CNC metal-cutting machines — fiber laser cutting machines, plasma cutting machines, and large-format solutions. As a result, we base our choice of technology on an analysis of the specific part: material, thickness, hole diameters, edge quality, heat affect zone, productivity, and unit cost—rather than on a single, simplified characteristic. It’s best to start with a drawing of the part, the type of material, and information about the subsequent process.

Summary — Laser or Plasma?

There is no single answer to the question “laser or plasma.” Fiber laser cutting typically provides greater edge perpendicularity, a narrower heat-affected zone, and the ability to make very small holes; plasma cutting offers a smooth edge and high practicality in the production of steel structures, welded components, and machine parts. The choice depends on the material, thickness, part geometry, holes, quality requirements, and subsequent production stages—not just the steel plate thickness itself.

Frequently Asked Questions — Laser or Plasma