How do laser cutters work

Laser cutting: process, advantages & disadvantages

Laser cutting, also called laser beam cutting, is a cutting process with a laser for plate-shaped material such as steel, aluminum but also wood. The basis for laser cutting is the interaction between the laser beam and the workpiece. Laser technology is often used for sheet metal processing.

Synonym (s): laser beam cutting, CNC laser cutting

technology

This technology was introduced into industrial practice more than two decades ago. Focusing optics bundle a light beam in a focus. A highly focused and high-energy laser beam acts on a workpiece, creating a melt and metal vapor, which are blown out by a high-pressure gas flow. The laser beam creates a cutting gap or kerf, which can have any cutting edge depending on the laser beam. A wide variety of cutting tasks can be mastered with laser cutting. On the one hand, these tasks include cutting kerfs accurate to the millimeter in extremely thin materials and, on the other hand, cuts in metals up to 30 mm thick. Various types of lasers can be used for laser cutting. Mainly CO2 lasers and fiber lasers are used in industry.
Almost all metallic materials can be processed on the laser cutting systems known on the market - structural steel, stainless steel and aluminum make up the major share here.

Components & construction

The most important components are:

  • Laser beam source
  • Laser beam guidance
  • Processing head (focusing optics) including cutting nozzle

In the near infrared (fiber laser, disk laser) the laser beam can be guided to the processing point via fiber optic cables, with the CO2 laser via deflection mirrors.

Procedure

With laser cutting, a distinction is made between three different processes depending on the type of material and gas.

Laser beam fusion cutting

Laser beam fusion cutting is a non-contact laser cutting process that is often used to cut stainless steel and aluminum alloys. With laser beam fusion cutting, the workpiece to be processed is locally melted by a laser beam. More precisely, the material is cut by constantly melting the cutting gap with a low-reaction gas, which removes the melted material and thus prevents the cutting surface from oxidizing. When cutting, nitrogen or argon is often used as the process gas, which prevents the material from reacting chemically. Post-processing of the cut edges is not necessary with laser beam melting, since the cutting surfaces do not oxidize and therefore no burrs are formed at the cutting gap during the cutting process. It should be noted that the cutting process in laser beam fusion cutting should be carried out by a powerful solid-state laser in order to achieve a good cut quality. Furthermore, the cutting quality of the process can be influenced by factors such as feed speed, cutting gas pressure, focus position and the strength of the laser source. Fusion cutting can be used with all fusible materials.

The effect and structure of laser cutting is explained.
The principle of laser cutting shown in a symbol graphic.

Laser cutting

In the case of laser flame cutting, the workpiece to be processed is locally heated by the laser beam to such an extent that it burns spontaneously after it has melted. Most of the material is burned with an oxygen jet that flows onto the heated area. The resulting iron oxides (slag) are mixed with molten metal and expelled by the oxygen jet, creating the kerf. The oxygen as a gas serves as an additional energy supplier (up to 5 times the laser energy) due to the exothermic reaction (oxidation) with the material. It should be noted that this type of laser cutting requires mechanical post-processing, as the cutting surfaces oxidize during the process. The oxidation results in the formation of burrs on the cut edges, which can, however, be avoided by setting the process parameters. The application of this process is suitable for ferrous metallic materials, for example it is most often used in the sheet metal processing of steel. The high cutting speed can be mentioned as a special feature of this process. Another special feature is that this laser cutting process can cut thick materials up to a thickness of 30 mm.

Laser beam sublimation cutting

In the case of laser sublimation, the evaporation of the heated material is decisive. This means that materials change from a solid state to a gaseous state without becoming liquid (sublimation). This is why this process is used for materials that do not have a pronounced molten state. The process gas (air, nitrogen, argon or helium) not only blows the steam that is created during the sublimation of the material out of the kerf, but also prevents the steam from condensing at this point. In short, the material vapor creates a high pressure in the kerf, which ensures that the melt is thrown up and down.

This method is particularly suitable for cutting organic materials such as:

  • Wood
  • cardboard
  • leather
  • textiles
  • homogeneous and fiber-reinforced plastics.

The cutting edge that results from this process is burr-free and smooth. This method is particularly suitable for cutting tasks that are particularly fine, for example cutting stents in medical technology.

Key figures & parameters: checklist

Focus position / focus diameter
The power density, the gap width and the shape of the kerf are dependent on this.
Laser power
A simple calculation determines the laser power: Energy (per area) = exposure time x power density
Nozzle diameter
The shape and amount of gas of the gas jet depend on this.
Operating mode
Continuous or interrupted - two ways of operating mode are possible.
Cutting speed
Higher laser power leads to higher, thicker material to lower cutting speed.
Degree of polarization
The degree of polarization is decisive for the quality of the cut, changes in direction change the cutting result.
Cutting gases
Cutting gases can, for example, be argon or nitrogen and, like laser welding, shield the environment (= protective gases).
Cutting pressures
The cutting pressures depend on the gases used and drive them through the kerfs.

Advantages and disadvantages of laser cutting

advantages

The laser is generally a very flexible tool, with which different materials of different thicknesses can be cut. With laser cutting, the cutting gap is very narrow and the quality of the cutting is very good compared to other cutting processes. Depending on the laser cutting system, all materials can be cut. Furthermore, depending on the material and laser cutting process, a clean, narrow and often post-processing-free cut edge can be achieved. In addition, laser cutting offers a high level of material utilization and is therefore very economical. The engraving or marking and cutting of products is often possible with the same beam source and within the same operation.

disadvantage

The disadvantages of this laser technology include high system costs, strict occupational health and safety, high energy consumption and gas consumption, depending on the laser beam source.

Supplier for laser cutting & manufacturer of laser cutting systems

There are a number of manufacturers for laser cutting systems:

Rofin Sinar
Rofin offers laser beam sources for laser cutting systems.
Epilog laser
Epilog is a manufacturer of laser engraving, laser marking and laser cutting systems.
Gödeke Metall & Laser
Gödeke offers laser cutting systems for 2D laser cutting and 3D laser cutting.
TRUMP CARD
TRUMPF produces and sells laser cutting systems that are suitable for laser cutting various materials.
MWW LaserDesign
MWW LaserDesign is a manufacturer and service provider of laser cutting and laser cutting as well as laser engraving and laser marking.
Krol
With Krol, the laser cutting of contacts, circuit boards, conductor tracks and other products can be carried out.

On the wiki page laser cutting machines even more manufacturers are listed and further information on the function of the respective machines is explained.

Laser cutting costs / prices

In principle, the following applies: Specific figures cannot be named. The reasons for this are different applications, providers, project sizes, etc. However, various cost factors that can be individually calculated provide an indication:

  • Material type
  • Material thickness
  • Cutting length
  • Cutting time
  • Number of special features (such as openings)

Laser cutting software / laser cutting software (CAD / CAM software)

Different designs can be created in advance, which will later be used for laser cutting. Different software can be used, which can be better or worse depending on the application and size of a company. In addition, software for data preparation is produced, which is supposed to save time with laser cutting. For planning and / or illustration, these can be the following:

  • Adobe Illustrator: By creating 2D designs and vector graphics, individual designs can be modeled.
  • Inkscape: Inkscape is often referred to as the free version of Adobe Illustrator.
  • SketchUp: Various plugins that optimize laser cutting help with SketchUp.
  • SolidWorks: With SolidWorks 3D creation is possible, whereby different models can be sketched.
  • AutoCAD: Autodesk AutoCAD offers the possibility to display mechanical components such as gears.
  • almaCAM: The almaCAM software is adapted for all manufacturers and laser technologies and therefore goes beyond laser cutting.
  • CAGLIA: The CAM software from SoftGuide is programming software for beam processing processes, which also includes laser cutting.
  • other providers such as OnShape, SolveSpace or SolidEdge

Laser cutting online

There is the possibility to have laser cutting carried out online (so to speak, to order). For this, the "online dealers" need the data on the corresponding workpiece and then produce it themselves. Using a configurator, for example, certain shapes or workpieces can be designed and sent by the customer. Such providers are:

  • LTO: Laserteileonline.de
  • H.P. Kaysser: Laserteile4you.de
  • 247 TailorSteel
  • Sculpteo
  • Cutworks