A laser machine is a piece of equipment that generates a stable high-temperature beam that hits the surface of the workpiece with a small light spot with a high concentration of energy. At the point of incidence, the laser burns out the material and, depending on the settings of the device, removes the top layer from it or creates a through cut.
According to the principle of forming and transporting the beam, the machines that are widely used in production are divided into two groups:
CO2 lasers – devices designed to process all types of materials, excluding metals (with some of them, the beam can interact provided that thermal paste is applied to the surface, but this is rather an exception). The formation of the laser stream takes place in a sealed glass tube with several compartments. The main volume is filled with a mixture of gases, which is sensitive to the effects of electrical impulses. The tube itself is connected to a high-voltage ignition unit, which supplies discharges and thus activates the gas. Having come into an excited form, the gaseous medium begins to emit laser particles, which gradually leave the tube in a stable flow and fall into a reflecting mirror located in front of the exit. This reflector is the first of four lenses included in the optical system of gas lasers.This complex is designed to transfer the flow from the tube to the surface of the material. Correctly adjusted mirrors reflect the beam without loss in power and speed. The last reflector, which is a concave or convex lens, is placed directly above the working area and serves to focus the laser on a plane to a point of the required diameter.
fiber lasers – primarily designed to work with the entire metal group of materials. They are also used for engraving glass, stone and cutting double-sided plastics. The laser stream is formed in a cable, the length of which can be up to several tens of meters. The core of the cable is made of a transparent quartz fiber of small diameter (about 400-600 microns) with an alloying coating. A cladding of pump waveguides is located around the active fiber. The energy required to start the process of emission of laser particles enters the waveguides and the core from external sources – diode lamps mounted on the machine body. To increase the speed of photons, their power and increase other quality characteristics, notches are made at the ends of the fiber,thus changing the reflectivity of the material and converting its edges into optical resonators.
One end of the cable is located directly above the focusing lens. The stream escaping from the fiber falls directly on it and narrows to the desired size. The lens itself is installed in a laser head, fixed above the working table on a movable carriage.
Further operation of laser cutting machines is similar for both types of devices. The control program created in a graphic editor or a three-dimensional modeling system is loaded into the memory of the machine. The data from it is read by the CNC controller, which converts the digital codes into pulses that give commands to stepper motors or servo drives. The motors, in turn, move the tool portal, on which the head with the laser emitter is fixed. As the commands are executed from the first to the last, the beam moves along the surface of the material, step by step forming an image or a cut contour that exactly repeats the computer model.
