CNCrapidly conquered the high-tech material processing sector. Due to the high accuracy, processing speed, as well as the low unit cost of manufacturing products, laser machines began to appear where, until recently, the use of automatic processing was unthinkable (and even on “sophisticated” CNC machines!). The advantage of laser equipment is also ease of operation and maintenance. And besides, the work of a laser machine in close connection with a personal computer greatly simplifies the preparation of production – after all, the control program is created on the basis of a graphic sketch. This means that the work of a designer is almost a “ready-made” task for production!
Thanks to a wide range of models from different manufacturers, it is possible to choose the optimal type of CNC laser machine that best suits the requirements of a particular production. However, it is quite difficult for an unprepared buyer to understand the abundance of technical characteristics. And even more so, it is not easy to decide which model to prefer? And most importantly, what type of machine to choose – “gas” or “solid state”?
Features of laser processing Laser processing
technology is fundamentally different from contact mechanical cutting. When machining workpieces with a milling cutter or cutter, the sharp wedges of the cutting tool separate the layers of material that is removed in the form of chips. As a result, the surface of the workpiece acquires the desired shape. In CNC machines, the cutting tool moves along a programmed path, so the new surface shape exactly matches the digital model of the product.
A CNC laser machine operates in the same way – the movement of the head along the machining route is set by the CNC microcomputer based on the loaded program model. Only instead of a milling cutter, a laser machine acts on the workpiece material with a high-energy coherent monochrome beam – a laser. As a result of thermal action, the workpiece material evaporates. Correspondingly, the machine can cut or engrave the workpieces by “traversing” the product contour by the laser, or moving along the plane “line by line”.
Due to the peculiarities of physical processes, processing on a laser machine is faster than on a milling machine. And the quality of the seam and the edges of the cut turns out to be higher – since the rapid heating and evaporation of the material does not allow heat to spread into the body of the workpiece (all the heat from heating by the laser is removed with the exhaust gases). This provides a unique opportunity to work with finished products. And not just souvenir figurines, or sheets of advertising posters, but even properly functioning electronic devices, including laptops and iPhones (for engraving keyboards and cases, respectively).
An essential advantage of laser processing is the very thin cut seam and the complete absence of solid waste. Another plus is the low noise level and less wear on the laser machine during operation (compared to milling or turning equipment).
How does a laser machine work?
Comparison of laser equipment with milling machines is far from accidental. Their design schemes are very similar: a robust supporting body, a horizontal work table for setting the workpiece, a tool portal moving above the workpiece in several independent planes (three for a laser machine), and control electronics that control the operation of all equipment.
Relative to the workpiece, the movement of the emitter head is carried out thanks to the power elements – stepper motors. Control pulses for them are generated by the CNC system, due to which the laser head takes a position strictly defined by the program during processing. Laser radiation is generated by a special device – a tube with an active medium (and a built-in optical resonator). For this, an electric voltage is supplied to the tube (through a special transformer block). The beam from the laser tube passes through a system of mirrors (some of which are movable to ensure free movement of the emitter head) and is “collected” by a focusing lens on the surface of the workpiece being processed. The resulting laser “needle” is the cutting tool that the CNC system “drives” to obtain finished products from a “raw” workpiece.
What is the difference between a gas laser and a solid-state laser?
As is known, to obtain laser radiation, an active medium, pump energy and an optical resonator are required, which forms a stable flux of photons of the required wavelength. Existing models of CNC machines can be equipped with gas or solid state lasers. In gas lasers, the active medium is a mixture of CO2, nitrogen and helium. In solid-state, special single crystals are used to generate lasers. In the first case, the pumping energy is an electric current (forming a gas discharge), in the second – a stream of light (from a lamp or LED backlight).
The fundamental difference between these types of lasers is the wavelength of the generated radiation. Not every material will be “transparent” to laser waves of a certain energy. Accordingly, these types of lasers are designed, strictly speaking, to work with different materials. For gas lasers, these are wood, plastic, rubber, leather, paper (and a number of others – excluding metals). For solid-state – mainly only metals (although other materials can also be engraved – the only question is the profitability of such a process).
Thus, for a CO2 laser (in comparison with a solid-state one), the following features can be distinguished:
- significantly lower cost;
- great ease of use;
- great versatility;
- compact size;
- greater variety of desktop areas (for different model lines of machines);
- practically absent ability to work with metals (with the exception of engraving – and even then with the use of special pastes or sprays);
- shorter laser tube life;
The aforementioned “features” of CO2 lasers are deliberately not divided into advantages and disadvantages, since gas and solid state CNC machines are not direct competitors. Where high-performance engraving and marking of metal products is required (with the possibility of through cutting of metals up to 0.5 mm thick, as well as spot welding of metals), a solid-state CNC laser machine is suitable. In all other cases, it is easier and cheaper to use machines with a gas laser tube.