Laser Cutting Methods Used on Steel Sheets

What is laser cutting?

When a highly focused laser beam is pointed towards a metal, it vaporizes and melts, resulting in a cutting edge of good quality. A high-powered laser is generated through optical methods, and the output is aimed at a hot-rolled sheet using a commercial motion control system to wedge cuts into the steel, forming designs and patterns.

What does a laser cutting machine consist of?

A CNC laser cutting device consists of the following:

● A converging lens or a concave mirror. This is also known as a ‘moving processing head’.

● A laser source.

● A system to guide the laser beam.

A laser beam usually falls under the near-infrared wavelength. A deflecting mirror is utilized in a carbon dioxide laser which helps converge the beam at the focal point of the mirror or the processing head. Once the beam is converged, the power generated is close to 109-1006 watts per centimeter square.

Process of laser cutting on steel:

The area to be cut absorbs the energy from the laser beam. The nozzle on the device provides the gas required for cutting through steel. The gas shields the concave mirror from vapors and splashes, thus getting rid of the extra material from the cutting front of the metal sheet.

There are three kinds of laser cutting methods:

● Laser beam fusion cutting- It is a no-contact process chiefly used on stainless steel. Nearly inert process gas is used to continuously melt the cutting area. The molten metal is removed in order to prevent oxidation of the cutting front. The gases used are nitrogen and inert argon. Since oxidation does not occur at the cut edge, the finish is of high quality. In the laser beam fusion method, carbon dioxide is not used. Instead, a solid-state laser is preferred. Four aspects affect the end result; the pressure of the process gases, the rate of feed, the power of the source of the laser, and the position of the focal point. 

● Laser beam flame cutting- Combustion occurs spontaneously on the cutting front of the metal. The burning procedure is due to a jet of oxygen gas-directed locally at a certain point. Oxygen removes the iron and oxides by melting the metal away. The exothermic process of oxidation provides an extra burst of energy. The speed and power of this method can cut up to 30 mm of metal.

● Laser beam sublimation cutting- The heated metal changes its state to gaseous without melting into liquid. The process is called sublimation. This process is used for metals that have a very high melting point, so much so that it exceeds the temperature of evaporation. The process gases used are nitrogen, argon, and helium, preventing steam condensation due to low chemical reactivity.

Conclusion:

Cold-rolled steel prices per kilogram for construction industries are rather expensive. Furthermore, laser cutting of steel is quite costly due to the complexity of the devices used. Therefore, to maintain a balance between quality and cost, one may turn to JSW for its customized services concerning the rapidly escalating markets in steel manufacture.