Views: 1440 Author: Site Editor Publish Time: 2021-10-18 Origin: Site
The working principle of the laser cutting machine is to melt and evaporate the workpiece by the energy released when the laser beam is irradiated on the surface of the workpiece, so as to achieve the purpose of cutting and engraving. The laser cutting machine has the characteristics of material saving, smooth incision, high precision and fast processing speed. , The laser cutting machine has the following eight main parameters.
1. Feed speed
The continuous cutting time of the laser beam at the current point is inversely proportional to the moving speed of the cutting head on the material plane. The higher the speed, the shorter the duration and vice versa. Sometimes some geometric parameters also affect the speed. For example, in the case of similar time, if the cutting part space is too small, it will cause heat accumulation of the material.
2. Cutting head height
The laser beam is focused under the nozzle through the lens, and the power density at the focal point is the largest. Therefore, the height of the cutting head from the cutting surface not only affects the focal area of the plane, but also affects the energy density at the current point.
3. Base photocurrent
Directly determines the power of the laser beam. When the ratio is 100%, the power of the laser beam is maximum.
4. Laser pulse frequency
In addition to continuous laser beams, pulsed laser beams are also used, that is, laser beams that are continuously and rapidly switched. By adjusting its duty cycle to adjust its power to achieve some special functions.
5. Laser pulse duty cycle
That is, the percentage of the time that the pulse laser is continuously on in one cycle is proportional to the laser power. When the duty cycle is 100%, that is, it is fully on within one cycle, that is, continuous laser.
6. Laser power supply
The laser power supply is divided into several parts to provide energy, and when necessary, some parts are turned off separately to reduce the power of the laser.
7. Laser power modulation
In order to match different cutting speeds, use special equipment to adjust laser power at any time. For example: when the cutting direction is changed, the translational speed of the cutting head will be lower than that of straight-line cutting. If there is no real-time adjustment of power in this section, the energy release in this section will be too high and affect the cutting quality; so it is necessary to use a modulator to reduce the laser. power to suit corner cutting needs.
8. Auxiliary gas
It is injected from the nozzle to protect the cutting head from smoke and dust, so as to improve the cutting quality. Although this factor has nothing to do with the laser power and the duration of the current spot cutting, it is a very important factor for metal cutting; there are several different gases to choose from to suit the cutting needs of different materials.
Laser machining technology offers a lot of different features for different industries. Regardless of features, the basic working process of most of these machines is the same. Here are the steps to the working of a CNC laser machine:
The machine’s work starts when the operator loads the G-code on the system. The G-code instructs the laser cutting machines on the movement directions.
Once the machine operation begins, the laser resonator generates the light beam. The process of laser generation can be different for various type of lasers. The color of laser can also be different. For instance, in CO2 lasers, laser generator emits an infrared light. This laser beam is entirely visible to human eyes.
A direction system diverts the laser beam to the focussing system. A series of mirrors can change direction. A specialized beam bender can also bend the generated laser to the focussing area.
A focussing system reduces the width of the laser beam and increases its power. This is done with a laser focusing head and a focusing lens. The focusing system also ensures that the focused laser beam is completely round with no stray light. The laser beam emits the machine through a nozzle.
The focused laser beam is directed to the workpiece material. The point of contact is exposed to the laser beam long enough to melt the material. The duration of exposure varies on material thickness and type.
The mechanical system moves the laser head in the required shapes, as the G-code directs. The speed of movement varies based on the particular job.
In CO2 laser cuttings, the laser amplification occurs through a CO2 gas discharge. CO2 lasers are one of the earliest and most popular types of lasers. The gas discharge isn’t entirely Co2. It contains CO2, Nitrogen, Hydrogen, Xenon, and Helium.
C02 laser cutting comes with two options: using Oxygen or Nitrogen gas. Oxygen gas is preferred for laser cutting thicker materials. Nitrogen gas is preferred for laser-cutting thin sheets. Using oxygen C02 laser cutting creates an oxide layer on the cut surface. Pre-treatment processes such as blasting are done on the workpiece to avoid this.
Fiber lasers use optical fiber for light amplification instead of conventional gas discharge. Light emitted through laser diodes passes through the optical fiber. The resultant light beam is sufficiently strong to melt away stainless steel up to 1 cm in thickness.
A strong airflow system often accompanies the light beam. The airflow pushes away the molten material for a clean cut. The fiber optics of these lasers utilize several elements like Ytterbium, Neodymium, Erbium, and Dysprosium.
There are three different configurations for laser cutting machines:
In moving material configuration, the laser head is completely stationary. The workpiece material is moved relative to the laser cutting head. The benefit is that there is a single location where the removed material is accumulated. This makes material extraction easier. However, the cutting speed of this process is slower because moving a large workpiece is more difficult than moving the small cutting head.
Another main advantage of moving material configuration is that the laser’s travel distance remains constant. Therefore, fewer optics are required.
The hybrid configuration has a partial movement of the material and partial movement of the cutting head. Conventionally, the material moves along the X-axis, and the laser moves along the Y-axis since the latter is shorter.
The distance that the laser beam travels is not constant. When the cutting head moves in Y-axis, the distance between the resonator and the cutting head will keep on changing. Therefore, some compensation is required to keep the power of the laser constant. This is done by increasing optics in comparison to moving material configuration. However, the working process of these lasers is faster.
Flying optics configuration has a movable cutting head but a stationary work table. The cutting head can move in both the X and Y axis. Flying optics configuration provides a faster cutting speed among all three options.
However, the laser distance constantly changes as the cutting head moves. This requires a complex optics setup that can account for the variable distance.
Accuracy: Laser cutters have the highest precision among any cutting methods. The high precision comes from the light being narrowed down to an extremely thin diameter. The accuracy is even higher than processes like water jet cutting.
Speed: Laser cutting thin materials is extremely fast. The speed can easily be over 3 meters per minute. Therefore, laser cutters are common in mass-production assembly lines.
Versatility: Laser cutting works on a lot of different applications and for many different uses. This makes it a very versatile cutting method.
Customization: It is possible to create personalized and customized shape by simply changing the CNC program.
Automation: Modern CNC laser cutters work with CNC systems. CNC can automatically control the movement of the cutting head.
Dust-free Cutting: Using a laser does not create any material dust in the workpiece. For instance, there is no sawdust when cutting wood with fiber lasers.
Less Waste: A laser cutter is very precise and removes very little material from the workpiece. This leads to minimum material waste. It is extremely useful when cutting precious metals where wastage can lead to losses.
Budget: Laser cutters are industrial equipment. It can be tricky to fulfill their initial investment and maintenance costs if you are on a tight budget.
Safety: Safety is not a big limitation with modern lasers as they come with safeguard measures. However, the operator still requires safety training.
Unsafe Materials: Certain materials are unsafe for cutting with a laser. It is important to know these materials beforehand to avoid machine damage and human injury.
Thickness: Laser cutting works well for thin materials like sheet metal. However, it doesn’t work for thick materials like metal blocks.
Here are some of the alternative cutting techniques that industries use and their performance in comparison to laser cutters:
Water jet cutting stands its own against laser cutters. Waterjet provides the benefit of no molten material since it is a cold-cutting process. Laser, however, provides benefits such as a better edge and higher precision. The lack of water requirement is another point in favor of laser cutters.
Plasma cutting also works by melting the material at the cut area. However, plasma cutting only works for electrically conductive materials like metals and alloys. This is a huge disadvantage of the process. Laser cutters can work on any material. They also provide engraving properties.
EDM cutting removes material by electrical discharges. Like plasma cutting, EDM is also limited to conductive metals. However, laser works on all materials and provides better results. Laser is also capable of engraving, but EDM is not.
CNC machines like mills and lathes rely on physical cutting tools. These tools wear out fast due to friction with the material. However, a laser requires no physical tools. Additionally, laser cutters provide better precision than CNC machines.
Punching creates cutouts through the physical force of the die. Punching can be a cheap metalworking process. However, the quality and precision of punching is quite poor. Laser cutters provide much better results.
3D printing is used for the additive manufacturing of plastic materials. They cannot replicate the results of laser machines. 3D printed products have significant defects that are often visible. The results of 3D printers are quite inferior to a laser machine. Additionally, 3D printers have a limited material range.
Laser cutting techniques are the go-to method for any application that requires precision and quality incisions. Laser marking processes take the capabilities of the technology a step further.
Lasers can cut the hardest materials and easily engrave workpieces without cutting them completely. If you are looking for industrial cutting equipment for your workshop, laser cutters can be the perfect fit.
