Laser cutting ...
Laser cutting is a technology for cutting materials with a high power laser commonly used in industrial production lines. A focused laser beam, normally controlled by a CNC-controlled computer, provides a high energy concentration and enables the cutting of almost all material groups, regardless of their thermophysical properties.
During the cutting process, the material of the material to be cut melts under the influence of a laser beam, ignites, evaporates or is blown out by a gas flow. This allows accurate cuts to be made with a minimum thermal zone of influence. The laser cutting is characterized by the absence of mechanical influences on the material to be processed, minimal deformations occur both temporarily during the cutting process as well as after complete cooling. As a result, the laser cutting of equally easily deformable and non-rigid workpieces and parts can be performed with high accuracy. The enormous power of the laser radiation ensures a considerable productivity of the work process with at the same time a decent condition of the cut surfaces. The precise and easy control of laser radiation enables laser cutting along the complex contour of flat and voluminous parts and workpieces with a high degree of automation of the process.
For laser-cutting metals, technical systems based on solid-state, fiber and gas CO2 lasers are used which operate in both pulsed periodic and continuous radiation modes. The industrial use of gas laser cutting is increasing from year to year, but this process can not completely replace the traditional methods of metal separation. Compared to many equipment used in production, the cost of laser cutting equipment is still high. Although lately there is a tendency to reduce costs. In this regard, the laser cutting process only becomes effective when there is a reasonable choice of application or when the use of conventional techniques is cumbersome or impossible.
The laser cutting is done by burning workpieces with a laser beam. This technique offers many obvious advantages over many other cutting methods:
- The non-existent mechanical contact allows the processing of easily deformable and brittle materials.
- Carbide materials are suitable for processing;
- Cutting steel sheet is possible at high speed;
- In the production of small quantities of product, it is more convenient to have the material laser cut than to produce expensive molds or molds;
- For automatic cutting of material, it is sufficient to prepare a drawing file in any drawing program and transfer it to the installation computer.
All steels of all states, aluminum and its alloys as well as other non-ferrous metals are suitable for laser cutting. Commonly used sheets of such metals:
Steel from 0,2 mm to 30 mm
Stainless steel from 0,2 mm to 40 mm
Aluminum alloys from 0,2 mm to 25 mm
Brass 0,2 mm to 12,5 mm
Copper from 0,2 mm to 16 mm
Different laser types are used for different materials.
Low thermal conductivity metals work best because the laser energy concentrates in a minimal volume of metal. Conversely, when laser cutting metal alloys with high thermal conductivity burr may arise. Many non-metals like wood can also be processed.
The laser and its optics (including the focusing lenses) must be cooled. Depending on the size and configuration of the system, excess heat can be dissipated by heat carriers or air blowers. Water, which is often used as a coolant, normally circulates through a heat exchanger or cooling unit.
The efficiency of industrial lasers can vary between 3% and 65%. Energy consumption and efficiency depend on the output power of the laser, its operating parameters and the suitability of the laser for a particular job. In determining the appropriateness of the use of this or that laser type, the cost of the laser in connection with its equipment and the cost of maintaining and maintaining the laser are taken into account. In the 10 years of the 21. Century, the operating costs of a fiber laser about half the operating costs of a carbon dioxide laser. The power required to cut depends on the type of material, its thickness, processing environment and processing speed.
Laser cutting is done by burning through sheet metal with a laser beam. A compressed, focused light beam offers a high concentration of energy and enables the processing of almost all materials - metal, plastic, wood - thermophysical properties are secondary.
Laser-cutting in detail
Laser cutting is a basic way of metalworking that is characterized by extremely high accuracy and excellent performance. Laser cutting machines have revolutionized the world of metalworking, making the process of making complex metal structures simpler, faster and more affordable. Nowadays, this type of cutting continuously supplants other types of metal working.
Laser cutting metal is a unique way to get the required product configuration for all print runs at a low cost. This process does not require the production of expensive molds and the configuration of the products is specified in the program and can be promptly edited at any time. Thanks to laser cutting, manufacturing companies have a unique opportunity to quickly produce the required products and make the necessary corrections.
The essence of laser cutting
The laser-cutting of metal is, as the name implies, carried out with a laser beam, which is produced with a special system. The properties of such a beam allow it to focus on the surface of a small area, generating energy characterized by high density. This causes each material to actively collapse (melt, burn, vaporize, etc.).
For example, with laser equipment or laser cutting machines, you can concentrate energy at a density of 108 watts per square centimeter onto the surface of the workpiece. To understand how to achieve such an effect, one needs to know what properties a laser beam has:
+ In contrast to light waves, the laser beam is distinguished by the constancy of the wavelength and frequency (monochromaticity), which makes it possible to focus it on any surface with conventional optical lenses.
+ Exceptionally high directivity of the laser beam and low divergence angle. Due to this property, laser focusing devices can produce a beam with a huge focusing effect.
The laser beam has another very important quality - coherence. This means that many of the wave processes that occur in such a beam are completely consistent and in resonance with one another, which at times increases the total radiant power.
When the light beam is applied to the metal surface, rapid heating and subsequent melting of the area to be treated occur. Several factors contribute to the rapid spread of the molten zone deep within the workpiece, including the thermal conductivity of the material itself. Further exposure of the surface of the product to the laser beam causes the temperature in the contact zone to reach the boiling point and begin to volatilize the processed material.
The use of oxygen as an auxiliary gas in laser cutting enables the simultaneous solution of such important tasks as:
- Activation of the metal oxidation process (this makes it possible to reduce its reflectivity);
- Increase the heat output in the cutting zone (as the metal burns more actively in the environment of oxygen);
- Blowing small metal particles and combustion products from the cutting zone with oxygen, which is supplied under a certain pressure (this facilitates the gas flow into the treatment zone).