Laser cutting is one of the most popular processes that widely used for many years. It is a subtractive machining process that removes unwanted material and creates the required shape during the cutting process. The word ‘Laser’ stands for Light Amplification by Stimulated Emission of Radiation. It uses an intensely focused, high-powered, coherent stream of light called laser to cut through the material. It is suitable to be applied on a vast range of materials, sizes, thicknesses and able to cut into complex shapes that traditional drills may be hard to complete the task. Besides the cutting, it can also perform other operations such as joining, drilling, heat treating, engraving, marking, or other processes that require higher power densities and shorter interaction times.
During the laser cutting process, the laser beam is actually melting the material away to create an accurate and smooth cutting edge. Depending on the materials we are cutting and other requirements, we can control and adjust the intensity, length, and heat output of the laser beam to achieve desired machining result. We also use a mirror or special lens to further focus the laser beam on the material.
Common Types of Laser Cutting Machines
There are three types of laser machines which are carbon dioxide (CO2), crystal laser, and fibre optic laser. All of them are having different types of working principles and they differ from each other on the base material used to generate the laser beam.
CO2 laser is a gas-state laser and the most common type of laser cutting machine. It employs a carbon dioxide mixture as a laser medium. The gas mixture is filled with carbon dioxide (10-20%), nitrogen (10-20%), hydrogen, xenon, and helium. The CO2 laser is produced inside a glass tube with guest sealed. A high voltage of electricity is passed through the tube that excites the gas particles to produce a high-powered infrared light which is known as the laser beam. The mirrors reflect the light traveling through the tube and build up the intensity of the light waves. Then, the light goes down to the head through a focusing lens that is inside the nozzle to concentrate the beam and channel it onto the workpiece. The CO2 laser is more suitable for cutting non-metal or organic materials such as leather, rubber, wood, etc., and performs engraving on metal or other hard material.
Crystal laser belongs to solid-state laser cutting and it employs a variety of crystal mediums such as Neodymium Yttrium-Aluminium-Garnet laser (Nd-YAG) and Neodymium-doped Yttrium Ortho-Vanadate (Nd-YVO). It is high-powered and suitable for metal or non-metal cutting. Crystal laser is made up of pump diodes that are expensive and costly when the replacement is needed. It typically can use for up to 15,000 hours which is shortened and less durable than a fiber laser.
Fiber laser is a more recent innovation that also belongs to the solid-state laser. It uses fiber-optics as the medium to generate a laser. The optical fiber is doped with rare elements including ytterbium, erbium, neodymium, praseodymium, or holmium. These elements are used for amplifying the light and generate the laser beam for cutting. For instance, Erbium can generate light with a wavelength from 1528 up to 1620nm. It offers many benefits over other types of laser cutting. It is durable, simpler, and without gases, the requirement of warming up, and mirror realignments. Because the light travel through the fiber-optic can remain inside the fiber with the least energy losses, it is more efficient and has a higher energy conversion rate that around 75% of the power received is converted into the laser beam. Whereas, the CO2 laser only has around 20% of the energy conversion rate. As mentioned before, it generates the laser beam insider the fiber, so it can maintain a straight beam and high beam quality with ultra-focused features that can make incredibly small cutting. Fiber laser machine also requires less maintenance as it has fewer moving parts and adjustments needed to make. It can offer a longer service life span of nearly 25,000 usage hours.
Advantages Of Laser Cutting
Laser cutting offers a huge number of benefits over other conventional cutting methods.
Faster Speed - Laser cutting is able to cut the material accurately at a high speed and complete the work quickly to reduce the overall production time. It is suitable for both large and small scales projects. It also can program the multiple parts together and cut the material at once to improve efficiency.
Quality product- Laser cutters can perform complex cuts with a high degree of accuracy and precision. It can produce clean edges and smooth finishing as there will not have any excess debris during the process. In addition, since laser cutting is programmed by CNC CAD/CAM, it ensures that the machine performs the same cuts on each item and creates multiple copies of the same product. Laser cutting is an ideal choice for fabricating aerospace parts and medical devices that required high product quality standards with tight dimensional tolerances.
Non-contact process- The laser cutting process is a non-contact process, which means that the laser beam does not physically touch the material. Instead, it melts the material with intense heat. This process reduces the mechanical distortion and physical damage to the workpiece and associated moving parts, especially for thin and flexible materials.
Cost Optimization- Although the initial investment of the laser cutting machine is much higher than other cutting processes, the running and maintenance costs are comparatively low as it has low maintenance requirements and only needs inexpensive replacement parts. Additionally, the laser cutting machine is capable of performing multiple operations without the need of purchasing separate tools. It can reduce our equipment costs and the lead time when changing to a different process or operation.
Safety- The laser cutting process is safer and has less risk of operator injury because the beam is enclosed within a box and the process occurs within the enclosure. It also produces little noise during the cutting process, therefore the overall workplace environment and safety standards are improved.
Disadvantages Of Laser Cutting
However, there are some limitations on the laser cutting process that we need to consider when deciding whether laser cutting is the most suitable solution for our applications. The power consumption and the nature of the laser which include the setting of temperature, the distance of the laser, etc, all mainly depend on the material types, size, the thickness of the workpiece to be carried out in the cutting process. It is also not applicable to all kinds of materials. For instance, copper and aluminum may be too thick for laser cutting and they will reflect too much light under this process. Laser cutting on the plastic component can be expensive as we need a well-ventilated room for the laser cutting process since the plastic emits gas when exposed to heat and it can be harmful to our body and environment. In addition, laser cutting tends to have a higher energy consumption than other conventional cutting techniques. The laser beam is harmful as it can cause severe burns if it contacts to human body accidentally.
Different techniques have their own pros and cons, it is important for us to consider and understand all factors that affect the performance of the work when selecting the right technique for our applications.
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