What Is Laser Cutting?

Laser cutting is a non-traditional processing method that uses an intensely focused stream of coherent light called a laser to cut material. It is a subtractive process in which the material is continuously removed during the cutting process. This is accomplished by vaporization, melting, chemical ablation, or controlled crack propagation.

The laser optics are digitally controlled by CNC (Computer Numerical Control), making the process suitable for drilling holes as small as 5 microns. In addition, the process does not create residual stresses in the material, allowing the cutting of delicate and fragile materials.

Laser Cutting is a process of cutting profiles on the materials. It is a very effective technology that is not only used for industrial purposes but is also used for prototype developers and commercial artists.

In general, a Laser is a tool with a sharp, focused high power density source of energy. Being light, it can be conveyed onto a workpiece by optical fibre cables, lenses, and mirrors. It does not have any weight and does not exert any pressure on the job/workpiece. Laser cutting is a non-contact type process. So, no forceful clamping is necessary.

The job can be as thin as 10 microns or as thick as 25 mm or more. Also, because of its unique properties, it can process the jobs from close ( < 1mm) or from distance ( < 300 mm).

It is used in situations where processing is to be done on very difficult to approach locations where traditional tools cannot reach. Being zero weight, having zero inertia, it can be rapidly positioned or moved just by deflecting mirrors, so it is helpful in reducing cycle times.

Laser cutting is an amazing technology that results in higher efficiency and lower cost.

How Do Laser Cutting Work?

A laser cutting machine works similarly to a CNC machine, but it uses a high-power laser. The laser will guide the material or beam through the CNC and optical equipment. The machine will use the CNC, or G-code provided, to cut the material and control the motion.

After the laser beam is focused, the material will melt, vaporize and burn. In addition, when you blow the material with a gas jet, you can obtain a high-quality finished edge surface. The laser beam generation takes place in a closed container, where a lamp or electrical discharge stimulates the luminescent material.

The amplification of the luminescent material occurs after internal reflection through a partial mirror. This phenomenon continues until enough energy has accumulated in a coherent monochromatic light stream to allow it to escape. The intensity of the light increases after it has been focused on the working area using a fiber or mirror.

The laser beam diameter is below 0.32 mm at its thinnest edge. Conversely, the width of the incision can potentially be as small as 0.10 mm. However, this depends on the thickness of the material. If the material is cut with a laser cutter without starting from the edge of the material, then a perforation process is used.

Types Of Laser Cutting

For cutting, there are three primary types of lasers. They are CO2, Nd-YAG (neodymium yttrium aluminum garnet), and fiber lasers. They differ in the base material used to generate the laser beam.

Carbon dioxide lasers

This type of laser has a gas discharge medium filled with 10-20% carbon dioxide, 10-20% nitrogen, trace amounts of hydrogen and xenon, and helium. Laser pumping is done not by light but by discharge current.

As the discharge passes through the illumination medium, the nitrogen molecules are excited to a higher energy level. Unlike previously described, these excited nitrogen molecules do not lose energy due to photon emission.

Instead, it transfers the energy of its vibrational modes to the CO2 molecules. This process continues until most CO2 molecules are in a transferable state. The carbon dioxide molecules then emit infrared light at 10.6 µm or 9.6 µm, bringing them to a lower energy level.

Resonant mirrors are designed to reflect the emitted photons at these wavelengths. A mirror is a partial reflector that allows the release of the infrared beam used to cut the material.

After releasing the infrared light, the CO2 molecule returns to the ground state by transferring its remaining energy to the doped helium atoms. The cold helium atoms then become very hot and are cooled by the laser’s cooling system. CO2 lasers have an efficiency of about 30%, higher than other lasers.

Advantages:

Versatility in cutting various materials such as acrylics, woods, and textiles.
High precision and intricate detailing capability.
Minimal material wastage and clean cuts without the need for additional finishing.
Cost-effective for small to medium-scale production runs.

Applications:

CO2 laser cutting finds applications in industries such as automotive, aerospace, and signage due to its ability to cut intricate shapes with high precision.

Crystal (ruby, Nd and Nd-YAG) lasers

Unlike CO2 lasers, this type of laser is a solid-state laser that uses synthetic crystals as the light-emitting medium. The most common is a YAG (Y3Al5O12) crystal doped with 1% ionized neodymium (Nd3+).

The Nd ions in this crystal replace the Y ions in the crystal structure. The rods are approximately 10 cm in length and 6 to 9 cm in diameter. The ends of the YAG rods are polished and coated with a highly reflective material that serves as a resonator system.

A krypton flash or laser diode achieves laser pumping. This laser pumping excites neodymium ions to higher energy levels. After some time, the excited neodymium ions enter a lower, more stable state without emitting photons. This process continues until the medium is filled with excited Nd ions. From its degraded state, the Nd ion emits infrared light at a wavelength of 1064 nm.

Advantages:

Superior cutting ability in thicker metals like mild steel and titanium
Versatility in various industrial applications
High reliability and stability in harsh environments

Applications:

Shipbuilding: heavy-duty metal components and structures
Construction: structural metal fabrication
Defense industry: armored vehicle parts and components

Fiber lasers

Fiber lasers are a newer form of laser that emits light using optical fibers rather than gases (CO2 lasers) or crystals (Nd-YAG lasers). Because it uses optical fibers, fiber lasers are solid-state lasers that work similarly to crystal lasers.

The optical fiber is doped with elements such as erbium and ytterbium. Erbium produces light in the range of 1528 to 1620 nm. On the other hand, ytterbium produces light at 1030 nm, 1064 nm, and 1080 nm.

It is known that when light passes through an optical fiber, it stays inside with minimal energy loss. This makes optical fibers more stable than other types requiring accurate alignment.

Advantages:

Exceptional precision due to focused laser beam
High cutting speeds, enhancing production efficiency
Lower energy consumption compared to traditional methods
Minimal maintenance required, reducing operational costs

Applications:

Automotive manufacturing: precise components and intricate designs
Aerospace industry: lightweight alloys and components
Electronics: delicate circuitry and precise parts

What Materials Are Suitable for Laser Cutting?

Laser cutting is a versatile technology capable of processing a wide range of materials, each with unique properties and applications.

Understanding the suitability of different materials for laser cutting is crucial for optimizing manufacturing processes and achieving desired outcomes. This section explores ten key material types that are commonly used in laser cutting applications.

Metals: Metals are among the most common materials processed using laser cutting technology. They include stainless steel, aluminum, mild steel, and alloys. Laser cutting enables precise shaping and intricate detailing in metal fabrication, making it indispensable in industries ranging from automotive to aerospace.
Plastics: Plastics such as acrylic, polycarbonate, and PVC are ideal for laser cutting due to their versatility and ease of manipulation. Laser cutting allows for clean edges and intricate designs in plastic components used in signage, electronics, and consumer goods.
Wood: Wood remains a staple material in laser cutting applications, valued for its natural aesthetics and structural versatility. Laser cutting can create detailed patterns, engravings, and precise cuts in woods like plywood, MDF, and hardwoods, catering to industries from furniture making to architectural model crafting.
Fabrics: Fabrics like cotton, polyester, and nylon are increasingly processed using laser cutting for textile applications. Laser technology offers precise cutting without fraying, allowing for intricate designs in garments, upholstery, and technical textiles.
Paper Products: Paper and cardboard products benefit from laser cutting’s ability to create intricate patterns and precise cuts without physical contact, minimizing material distortion. Applications range from intricate invitations and packaging designs to custom artwork and educational models.
Foam: Foam materials such as polyurethane and foam core boards are easily shaped and cut using laser technology. This method is ideal for creating packaging inserts, custom padding, and architectural models with intricate details and precise dimensions.
Glass: Laser cutting techniques are adapted to process glass, offering precise cutting with minimal chipping or cracking. Applications include custom glassware, decorative panels, and intricate architectural components requiring high precision.
Ceramics: Advanced laser cutting technologies enable the precise cutting and engraving of ceramics, enhancing manufacturing capabilities in industries like electronics, aerospace, and artistic ceramics.
Rubber: Rubber materials, including silicone and neoprene, are suitable for laser cutting due to their elasticity and durability. Laser technology allows for precise cutting of rubber components used in seals, gaskets, and custom automotive parts.
Leather: Laser cutting is increasingly used in leatherworking for precision cutting and intricate detailing. It allows for customized designs in leather products such as footwear, bags, and upholstery, enhancing both aesthetic appeal and production efficiency.

What Materials Should not be Laser Cut?

Laser cutting is a precise and versatile technology, but not all materials are suitable for this process. Understanding which materials to avoid is crucial to ensure safety, maintain machine integrity, and achieve optimal results.

ABS (Acrylonitrile Butadiene Styrene): Emits toxic fumes when laser cut, posing health risks.
PVC (Polyvinyl Chloride): Releases chlorine gas, which is hazardous to both the machine and operator.
PC (Polycarbonate): Melts and produces harmful vapors when exposed to high temperatures.
HDPE (High-Density Polyethylene): Does not readily absorb laser energy, leading to poor cutting quality.
Laminated Fiberglass: Contains adhesives and coatings that can damage the laser optics and generate harmful emissions.
PTFE (Polytetrafluoroethylene): Releases toxic gases, including fluorine compounds, when heated.
Ceramics: Reflects laser beams, making cutting difficult and ineffective.
Reflective Metals: Reflects laser light, reducing cutting efficiency and potentially damaging the machine.

Advantages of Laser Cutting

Laser cutting is a widely adopted manufacturing technology. Listed below are some of the key advantages that make laser cutters such a popular manufacturing technology:

Versatile Materials: Laser cutters can process almost any material. The thickness of material that can be cut with a laser cutter depends heavily on the laser power, the laser technology, and the material being cut.
Limited Post-processing: Parts that have been laser cut do not require significant post-processing. However, in some cases, like cutting metal, cut edges may need to be deburred as there may be some slag attached to the cut edge.
Narrow Cuts: Lasers can be focused on very tight beams, meaning that cut widths can be very thin (as small as 0.1 mm) depending on the material and the thickness.
High Precision: Laser cutters do not experience any loads on the laser cutter head as is the case with other technologies like CNC routers. As such, laser cutters are very precise and accurate.
High Speed: Laser cutters can cut out 2D profiles very quickly. Cutting soft materials like plastic can be done at high speeds.
Automated: Laser cutters are highly automated. Some machines can even place raw material on the cutting bed and unload parts with limited human interaction.
Tooling Costs: Unlike CNC machining, laser cutters do not make use of a wide range of tools. There is no tool wear due to friction as the laser cutter head does not contact the raw material.
No Workholding: Laser cutters do not require clamps or other workholding equipment during cutting. Material can simply be placed on the cutting bed and will not move during the cutting process.

Disadvantages of Laser Cutting

Despite its many advantages, laser cutting still has some limitations as described below:

High Initial Cost: The initial capital investment of laser cutters is high. In some cases, cheaper technologies like flame cutters or plasma cutters may be better suited.
High Power Consumption: Laser cutting consumes a lot of power, especially technologies like CO2 laser cutting.
Limited Thickness: Due to the physics of focusing a laser beam into a high-intensity point, laser cutters are limited in how thick they can cut. They are generally limited to plate and sheet materials with a maximum thickness of up to 25 mm. While thicker material can be cut, this is not commonly done by standard fabrication shops.
Dangerous Fumes: When cutting some materials like wood or plastic, dangerous combustion fumes can be generated that must be vented.
Expensive Maintenance: Some laser technologies (such as CO2) consider the laser tube as a wearing item that must be replaced—at great expense.

Conclusion

The introduction of laser cutting has provided valuable benefits to the manufacturing industry. The machine helps to cut many materials in one period, thus saving time and reducing operating costs. Understanding the pros and cons of laser cutting will help you make the best choice for your project.

What Is Laser Cutting? – Working, Types & Application