Laser Cutting Working Principle, Advantages and Disadvantages

What Is Laser Cutting?

Laser cutting is a laser-based thermal cutting technique. This technique uses a laser source that produces a continuous or pulsed heat beam to cut metals and other materials. This makes the cutting process much more precise and clean. Laser cutting also consumes less energy than other cutting techniques and is environmentally friendly since it produces less pollution.

Laser beam machining is a thermal machining process that uses a laser beam to generate heat and remove material from a workpiece.

What Is “Laser”? It’s an acronym for “Light Amplification by Stimulated Emission of Radiation.”
Meaning: light amplification through stimulated emission of radiation. We could also describe it as light amplified through stimulated emission.

Laser Cutting Applications Video

https://youtu.be/SmqshFOi3kw

In this machining process, laser heat is used to melt and vaporize metal particles from the surface in a controlled way, removing them from the metal workpiece.

The laser cutting technique is used mostly for sheet metal cutting and piercing operations. However, it isn’t limited to sheet materials alone. Both metallic and non-metallic workpieces can be machined using this process.

Sheet Metal Laser Cutting Video

Cutting capacities are high. A 1 kW laser can cut steel sheets up to 10 mm thick, and cutting speeds can reach up to 10 m/min on 1 mm steel sheet.

Working Principle of Laser Machining

In laser cutting, a laser beam is used as the heat source. A laser is a linearized beam of light. This beam is produced by electrically exciting a laser gas, which is a mixture of helium, carbon dioxide, and nitrogen.

We also have a separate article about how a laser is generated and its operating system. For details, see: Properties and Working Principle of Laser Beams

The laser beam is focused (aimed) onto the material’s surface through a lens inside the cutting head, forming a spot 0.1 mm to 0.2 mm in diameter. The high energy density this produces — 10⁷ W/cm² at the burn spot — rapidly brings the material to be cut up to its melting temperature. The molten material is then blown out through the resulting burr-free kerf, 0.1 mm to 0.3 mm wide, by the cutting gas.

How Laser Beam Machining Works. How Does Laser Cutting Work

The steps used in laser beam machining are as follows:

First, the laser material — CO2 or another laser material — is loaded into the discharge tube.
Then, the power supply used to fire the flash lamp is switched on. The light from the flash lamp is used to excite the atom’s electrons.

The atoms of the laser material then absorb energy from the light energy produced by the flash lamp.

Because of this absorbed energy, the atom’s electron jumps from a lower energy level to a higher one. However, this is an unstable state for the atom.

Once the atom reaches its absorption limit, it begins to continuously emit energy. This energy is emitted as highly amplified, coherent light at the same frequency and wavelength.

This laser light emitted by the atom is gathered by a convex lens and directed onto the workpiece. When the laser strikes the workpiece, it starts the machining process by melting or vaporizing material from the workpiece’s contact surface.

Focal Distance

The focal distance of a laser cutting head is usually set between 5-15 mm depending on the thickness of the material being cut.

Use of Assist Gas

During cutting, assist gases such as oxygen, nitrogen, or air are used to blow the molten metal out of the kerf.

Cutting Speed

On thin sheet materials, a fiber laser can reach cutting speeds of several meters per minute.

Main Components of Laser Cutting

The main equipment used in laser beam machining is as follows: –

1) Power Supply: The power supply is used in laser beam machining to provide the energy needed
to excite the electron from a lower to a higher energy level.

2) Laser Discharge Tube:
The laser material is loaded into the laser discharge tube. The excitation of the electron and its return to its original state happen inside this laser discharge tube. One side of the discharge tube is partially transparent, while the other is 100% reflective. It’s positioned between xenon lamps.

3) Laser Material:
A wide variety of laser materials exist, but CO2 and Nd:YAG are most commonly used in laser machining. Carbon dioxide is a laser material that emits light in the infrared range. Carbon dioxide can deliver up to 25 kW of power in continuous-wave mode. Nd:YAG is a solid-state laser that can deliver light through an optical fiber. It can produce up to 50 kW in pulsed mode and up to 1 kW in continuous mode. Focusing lens: a focusing lens is used to focus the light onto the workpiece. It’s a convex lens.

Industrial Laser Marking Video (above)

Advantages and Disadvantages of Laser Cutting

Advantages

1) No physical tool is required, so there’s no tooling cost, and consequently no cost for maintaining or replacing tools.
2) Since there’s no physical contact with the workpiece, delamination doesn’t occur.
3) It can be easily automated and is very flexible.
4) Since the laser can be moved along any path, complex shapes of different sizes can be machined.
5) It provides very good surface quality.
6) Micro-holes can be pierced in the workpiece with high accuracy.