Laser Cutting / Laser Engraving: All You Need To Know
Laser cutting overview
Laser cutters use a highly concentrated beam of light to vaporize, melt, or burn materials in order to a cut or etch for a custom design.
So what materials can a laser cut? You can do custom laser cutting on materials such as metals, wood, acrylics, polymers, gems, and even paper. Because of its strength, solid materials like diamond tools and metallic alloys can be shaped.
How does a laser cutter work? The laser-cutting process removes or breaks a material through melting, vaporization, controlled crack propagation, or chemical ablation. Laser optics operated by Computer Numerical Control (CNC) can cut holes as little as five microns (µ) and do not create residual stresses on materials, which makes it cut through brittle and fragile materials seamlessly.
If you need material cut, check out our CO2 laser.
What is the process of laser cutting?
Laser cutting normally operates using a highly-powered laser controlled by CNC and optics. The process generally utilizes a motion control system to follow a CNC or G-code patterned onto the material. It then makes use of the laser beam to melt, burn, vaporize, or blow away a jet of gas to leave a smooth surface.
By stimulating lasing materials with electrical discharges or lights inside a confined container, the laser beam is produced. The lasing material is internally reflected by a partial mirror and amplified until it has sufficient energy to escape as a stream of coherent monochromatic light. A laser beam's diameter at its narrowest point is typically less than 0.0125 inches (0.32 mm), but depending on the material thickness, it can produce kerf widths as small as 0.004 inches (0.10 mm). A laser can then penetrate even on the most solid materials—it can be a wood laser cutter, metal laser cutter, and even
Types of laser cutters
CO2 laser cutters
A gas discharge lasing medium of this sort has a mixture of 10–20% carbon dioxide, 10–20% nitrogen, quantities of xenon and hydrogen, and helium to balance it all out. Laser pumping is carried out by releasing an electrical current rather than light. Because of this, nitrogen molecules are excited, raising the energy level of the lasing medium as the electrical discharge travels through it. These excited nitrogen molecules transfer the energy from their vibrational state to CO2 molecules. Until the majority of the CO2 molecules are in a metastable condition, this process keeps going. The CO2 molecules then give off either 10.6 µm or 9.6 µm infrared light, which lowers their energy levels.
The emitted photons at those wavelengths are intended to be reflected by the resonating mirrors. The infrared beam used to cut the material can be released from one mirror, which is a partially reflecting mirror. The CO2 molecules send their leftover energy to the doped helium atoms to return to the ground state after emitting infrared light. Then, the cold helium atoms heat up and are cooled by the laser's cooling mechanism. A CO2 laser has an efficiency of about 30%, which is higher than that of conventional lasers.
Fiber laser cutter
The latest and most widely used type of laser is the fiber-optic laser which can produce several wavelengths for more precise cutting. They direct the light using a silica glass optical fiber cable. Because it is smaller and straighter, the laser beam generated by fiber-optic lasers is more accurate. As silica glass coupled with rare earth elements serves as the power source for fiber-optic lasers, they are categorized as solid-state devices.
Crystal (Ruby, Nd, and Nd-YAG) lasers
This type is a solid-state laser that utilizes artificial crystals as its lasing medium. The YAG (Y3Al5O12) crystal infused with 1% ionized neodymium (Nd3+) is the most widely used. In this crystal, the Y ions have been replaced by Nd ions. The rod's diameter ranges from 2.4 to 3.5 inches, and its length is approximately 4 inches (10 cm) (6 to 9 cm). Highly reflective materials are polished and coated on the ends of the YAG rod to serve as the resonator system.
Varieties of Laser Cutting
There are three varieties of laser cutting: remote cutting, flame cutting, and fusion cutting.
Remote Cutting: Thin sheets can be sliced without the use of assist gas because a high-intensity laser beam causes the material to evaporate (ablate) partially.
Flame Cutting: The assist gas utilized is oxygen. This causes an exothermic reaction that boosts the process's energy input in addition to applying mechanical force to the molten substance.
Fusion Cutting: Molten material is ejected from the kerf using an inert gas, usually nitrogen. As nitrogen gas doesn't really interact exothermically with the molten substance, it does not add to the input power.
The laser cutting process is highly automated with offline CAD/CAM systems operating either three-axis flatbed systems for three-dimensional laser cutting. The laser process is gradually replacing traditional profile-cutting techniques like plasma and oxyfuel due to improvements in heat input control, edge squareness, and accuracy.
Laser Engraving Definition
The laser engraving process utilizes a laser beam to leave clearly visible marks on a variety of materials. This noncontact process is possible because of the beam's ability to focus on a spot size as small as a few microns. As a result, it can produce extremely intricate designs depending on its focal point. High contrast between the unengraved and engraved parts of a design can be produced when laser engraving. Signboards, personalized clothing, industrial labels, and other creative designs can be created with laser engraving. If you are looking for laser engraving services, we have the right machines to get the job done.
A CO2 or fiber laser is most frequently used for custom laser engraving. Both of these lasers can generate sufficient high-energy densities to vaporize and remove material in a predetermined manner in order to engrave a pattern on a target surface. Metal engraving with fiber lasers is more successful since most metals quickly absorb their wavelength. Since nonmetals like plastic, stone, and wood better absorb the CO2 laser's wavelength, a CO2 laser is more appropriate to be used.
How does laser engraving work?
The engraving during the laser engraving process is the product of combining the evaporation ablation and melting method. The material melts and partially evaporates due to the laser beam's intense irradiance resulting in a depression. A standard engraving depth ranges from 10 to 50 μm. Due to the evaporating substance's vapor pressure, the melt at the edge is forced out and solidifies into the melt rim as it cools. Due to the melt's inability to be entirely pushed out, the engraving takes the shape of a U and gets narrower as the laser penetrates the material farther. Locally, the narrow laser spot and the extraordinarily brief pulses in terms of time severely limit the heat input.
Types of laser used for laser engraving
Fiber lasers
When engraving, fiber lasers are highly powerful as they produce power ranging from 20-50 watts. Due to the high degree of filtration of monochromatic light beams, fiber lasers also have a broad spectrum of material compatibility, making them highly suitable for marking and engraving.
Excellent beam quality, extreme durability, flexibility, and suitability for use on intricate surfaces are all characteristics of fiber lasers. They are ineffective for marking thick or reflective surfaces, though.
CO2 lasers
CO2 lasers are the best to use when engraving organic materials like glass, plastic, ceramic, wood, etc., as they operate at a wavelength of 10,600nm with galvo-streered beams and sealed-tube laser systems.
In addition, CO2 lasers can also be used when engraving metals. However, the metal must first be treated with a specialized marking compound that sticks to the material in order to leave a permanent and high-contrasting mark. Also, CO2 lasers can be quite expensive because of their maintenance and operational costs. Nonetheless, it is highly effective.
UV lasers
UV rays with a wavelength of 355nm are used by UV lasers. They are ideal for engraving surfaces with low thermal sensitivity since they do not produce significant heat like other machines. They play a significant role in the marking of electronics, microchips, and circuit boards. It is safe to say that UV lasers utilize power well. However, due to their low power output and poor heat production, they have a restricted ability to engrave while working with materials like metals.
YAG lasers
YAG lasers are ideal tools for engraving thin metal sheets because they are portable, light, and efficient. They work well for engraving materials like steel and aluminum. They generate low-power laser beams, in contrast to conventional engraving devices. As a result, no material distortion occurs during the entire engraving process.
MOPA laser machines
By comparison, fiber lasers and MOPA laser engraving machines have similar designs and appearances. However, the Master Oscillator Power Amplifier gives the machines a high level of power efficiency in comparison to the fiber lasers, indicating that they have different internal technology.
MOPA laser generates a highly coherent beam that is intensified without diminishing its properties. In contrast to the 500KHZ of the fiber laser, the frequency is increased to 2700KHZ. MOPA lasers are incredibly adaptable and can engrave a variety of colors on stainless steel, high-contrast black engraving on anodized aluminum, and high-contrast engraving on plastics.
Procedures often used for laser engraving
Deep engraving
Deep laser engravings should be used for creating molds and tools for construction, as well as vehicle plate numbers. When doing deep engraving, several processes have to be carried out in order to attain the necessary depth. It can engrave deeper depths up to the millimeter range.
Black engraving
When using a laser to engrave metals, melted basic material reacts with atmospheric oxygen to produce oxides, which might vary in color. Depending on the roughness of the surface of the material and its ability to absorb light, the engraving appears to be black or dark gray on aluminum materials or dark brown when it's copper, steel, or brass.
White engraving
When doing white engraving, the surface of the material should be structured so that it will only be slightly melted. In materials like galvanized steel, this results in the creation of a smooth, highly reflecting surface that can be seen as a white marking. Due to the low-depth penetration, the coating is still intact and resistant to corrosion. For best results, use high-contrast white engraving on dark metals like hardened steel. While both white and black engraving works exceptionally well when applying data matrix codes as they raise the contrast and enhance the readability and quality of the code.
If you need parts cut or engraved, you’ve come to the right place: CO2 laser, fiber laser, CNC router table, 4th axis mill… and now CNC plasma table. Get in touch here and we’ll be happy to assist you.
