Introduction to the Principles and Classification of Metal Laser Cutting Machines

I. Principle

Laser cutting machines employ a high-power-density laser beam focused onto the workpiece. This causes the irradiated material to rapidly melt, vaporize, ablate, or reach its ignition point. Simultaneously, a high-velocity gas flow coaxial with the beam blows away the molten material, thereby severing the workpiece. Laser cutting is one of the thermal cutting methods.

II. Classification

Laser cutting can be categorized into four types: laser vaporization cutting, laser melting cutting, laser oxygen cutting, and laser scribing and controlled cracking.

1) Laser Vaporization Cutting

A high-energy-density laser beam heats the workpiece, causing its temperature to rise rapidly and reach the material's boiling point within an extremely short time. The material begins to vaporize, forming vapor. The ejected vapor flows at high velocity, creating a cut in the material as it escapes. Since materials typically possess high latent heat of vaporization, laser vaporization cutting requires substantial power and power density.

Laser vaporization cutting is primarily used for cutting extremely thin metals and non-metallic materials (e.g., paper, fabric, wood, plastics, rubber).

2) Laser Melting Cutting

In laser melting cutting, the laser heats the metal material to melt it. A non-oxidizing gas (Ar, He, N, etc.) is then blown through a nozzle coaxial with the beam. The powerful gas pressure expels the molten metal, forming the cut. Laser melting cutting does not require complete vaporization of the metal and requires only one-tenth of the energy needed for vaporization cutting.

Laser melting cutting is primarily used for materials resistant to oxidation or reactive metals, such as stainless steel, titanium, aluminum, and their alloys.

3) Laser Oxygen Cutting

Laser oxygen cutting operates similarly to oxyacetylene cutting. It employs a laser as the preheating heat source and uses reactive gases like oxygen as the cutting agent. The ejected gas reacts with the metal being cut, causing oxidation and releasing significant oxidation heat. Simultaneously, it blows molten oxides and molten metal away from the reaction zone, forming a cut in the metal. Due to the substantial heat generated by the oxidation reaction during cutting, laser oxygen cutting requires only half the energy of melting cutting while achieving cutting speeds far exceeding those of laser vaporization and melting cutting. Laser oxygen cutting is primarily used for easily oxidizable metals such as carbon steel, titanium steel, and heat-treated steel.

4) Laser Scoring and Controlled Fracturing

Laser scoring involves scanning a high-energy-density laser across the surface of brittle materials to evaporate a narrow groove. Applying controlled pressure then causes the brittle material to fracture along this groove. Laser scribing typically employs Q-switched lasers or CO₂ lasers.

Controlled fracture utilizes the steep temperature gradient generated during laser grooving to induce localized thermal stress in brittle materials, causing fracture along the groove.

The above outlines Top Optics Laser's explanation of the principles behind metal laser cutting machines. Metal laser cutting machines are automated equipment capable of automatic layout, significantly reducing material waste. The cut surfaces produced by these machines are exceptionally flat, with remarkably smooth edges. This equipment lowers processing costs during operation. Most manufacturing plants opt for this technology, as it effectively reduces both production and processing expenses for enterprises.