The Basics of Laser Cutting

The growing laser cutting community provides for many versatile applications from major metal cutting outfitters to small hobby shops. The advancements in technology and reducing cost to produce laser Computerized Numerical Control (CNC) machines has allowed for hobbyists to enter into the laser cutting field with minimal time and investment costs. In this blog post I explore an introduction into several different topics associated with laser cutting.

Understanding Laser Cutting

What exactly is laser cutting? Laser cutting machines are essentially a specific category of CNC machines. These are computer driven machines using code to follow a preprogrammed path either on a two dimensional grid (x,y) or three dimensional grid (x,y,z) while using a laser as the cutting instrument. Using a laser allows for precision cutting, reduction in material loss due to cutting and performing different functions, in addition to cutting, such as engraving materials. The ability to have a precise cut path and varying the output power of the laser can allow for cutting different materials and projects without having to remove or replace the cutting instrument. For instance, using a typical drill bit CNC machine, a user would need to switch out the drill bit if the cutting material was changed. Since the same laser can be used across a wide variety of material, a user can cut with a larger amount of versatility and perform many different functions with the same machine. Within the laser-cutting genre, there is further customization depending upon which type of laser cutter you decides to use which is explored in the next section.

Types of Lasers

Depending upon the function that you want to execute, there can be a different laser suitable for each type of cutting that needs to be performed.

Diode Lasers

These lasers use a process called “stimulated emission” that uses photons to excite atoms in a semiconductor to emit additional photons. These photons are reflected down through the body of the laser hitting more semiconductors “picking up” additional photons that eventually lead to a focused beam that will emerge from the laser head. These are small scale, low power lasers that are mainly used for etching and cutting thin materials such as wood and paper. These types are more likely to be found as hobby or small business machines ranging up to a max of 40W output (my laser is a 40W XTool). Diode lasers are typically entry-level machines for those wanting to be exposed to the laser cutting industry.

CO2 Lasers

These lasers follow a similar type of emission as the diode lasers with one major difference. Instead of using a semiconductor, a tube of CO2 is used as the laser medium. An electrical current is run through the CO2 tube causing atoms to transition to a higher energy state. When the atoms transition back to their initial state, it results in the emission of additional photons. The photons are reflected and focused from the tube to the laser head in order to develop a beam. CO2 lasers emit light in the infrared portion of the light wave spectrum, which makes them effective in cutting many different materials. These machines can range up in the strength of 1000s of watts, but typically a medium sized laser will go up to about 150W. These require a little more maintenance in taking care of the CO2 chamber and cooling units, but is definitely a step up in power from diode. This allows the CO2 class of laser to cut thicker and stronger materials and work at faster cut times. Many industrial applications will be using this type of laser.

Fiber Lasers

Some of the most powerful lasers on the market are fiber lasers. These can range upwards into the 10s of kilowatt range, that’s 10,000W and above! These are the serious, heavy hitting, industrial metal laser cutters. A far cry from the beginner diode laser. Again, these lasers use the phenomenon of “stimulated emissions” like other classes of lasers. The major difference this time is that the materials being excited are a specific doped optical fiber. The dopants are rare-earth elements like ytterbium, erbium and neodymium. The wavelength of the emitted photons of a fiber laser are around 1 micrometer, which is well absorbed by most metals. Due to the high power and easily absorbed wavelength, fiber lasers can also operate at higher speeds to cut down total cut time. This makes high-powered fiber lasers the choice to be used in large industrial metal cutting applications.

Overall, the many different types of lasers allow for an entry point for anyone from a hobby enthusiast to a large metal fabrication company.

Laser Cutting Process

The laser cutting process follows a typical engineering framework of design, fabrication and post processing and iteration. The design phase is most crucial to the process, where ideas can pivot and morph with great ease without the introduction of large capital losses. Depending upon the application, the design work can involve either 2D or 3D modeling software. If it is a one off part such as a wooden coaster, then typically a 2D software is involved, as the third dimension is just the thickness of the material. However, if multiple parts are being cut that must be interlocked together, then 3D modeling is required to ensure that the parts fit snugly and clearances are satisfactory. If the design is in 3D space, then it will eventually need to be translated into 2D for most laser cutters. Again, the third dimension is the thickness of the material being cut, so a 2D drawing is projected onto that surface for a total of three dimensions.

After designing within the modeling software is complete, fabrication begins with a drawing being exported to whatever software is being used to run the laser cutter. Many different software programs can run the brains of the machine, but my software of choice is LightBurn. It requires a one-time purchase for a single license and is compatible with many introductory to mid-level lasers. What this program does is take in different file formats such as .dxf or .svg and converts it into machine code to drive the x and y positioning of the laser. It makes the process of conversion and driving the laser cutter extremely user friendly. Adjustments can be made within the LightBurn software itself before the final cut button is pushed. Once tweaks are completed, the most exciting part of the process begins, watching the laser perform the cutting. Once completed, post processing is typically required depending on what has been cut. That could mean anything from sanding down edges, to assembling separately cut pieces. Finally, if everything is designed properly and you’re happy with the final product, that’s the end of the road. Sometimes everything isn’t quite right whether it was missed in design or fabrication and the final piece requires a little iteration to get to the desired final product.

Materials for Laser Cutting

Laser cutting offers a wide variety when it comes to material selection. Many different materials can be cut depending upon the model of laser with the power available and type of the beam. Some of the standard choices are wood, acrylic, metal, leather, plastics and textiles. Remember that the laser cutter can perform both etching and cutting on different materials, which allows many different projects to be cut on a single machine. There are safety considerations that should be considered depending upon which material is being selected. It’s always good to do practice cuts as well with a new material to dial in the specific laser settings to provide the desired final cut.

Advantages of Laser Cutting

Several major advantages come to mind when thinking of laser cutting. First and foremost is the exceptional precision and minimal material waste. Since the laser can be focused to hit a small target, the cuts made can be intricate and detailed. This also lends to a very small kerf being created. The kerf is the amount of material that is removed due to the cutting instrument. You can find out how to calculate the kerf and more information in our kerf blog post. Secondly, the speed and efficiency of laser cutting is second to none. Since the cutting instrument does not actually touch the surface of the material itself, there isn’t any degradation or drag to a cutting blade so the laser can move quickly across the material. This also allows for clean cuts and limited, if any burrs on a laser cut piece. Of course, cutting materials faster and more efficiently leads to lowered machining costs. Thirdly, the versatility has been mentioned multiple times previously, but this should be emphasized, as it is a unique quality for laser cutting. Being able to swap out materials within the same machine and going from wood to acrylic to metal allows for creating an innumerable amount of projects. Overall, using a laser cutter offers a wide range of advantages over other cutting methods, but like anything else, there are tradeoffs to be made.

Limitations and Considerations

Unfortunately, laser cutting is not the be all end all for every application and there are some negative drawbacks to using these machines. The main concern for laser cutting is that it’s not an efficient way to cut thick materials. Since there is no traditional blade, the laser itself needs to burn its way through a material. If a material is too thick requiring the laser to move slowly through the cutting, then laser has a tendency to produce burned edges. This can be fixed in the post-processing stage by sanding down the corners, but obviously adds time to the fabrication process. Another issue is that reflective materials cannot be effectively cut with lasers. Due to the reflective nature of materials such as aluminum or copper, the beam will be reflected away instead of properly cutting through the material. These types of metals would need to have a non-reflective coating applied or to be cut using traditional CNC milling machines. Finally, heat sensitivity and toxic fumes are two more limitations that go hand in hand. Since the laser is burning through the material, those materials that are more susceptible to burning will present issues when trying to make a clean edge. In addition, some plastics release toxic fumes when being cut so it is imperative to have proper PPE when dealing with these materials. Sticking to the right applications though will provide you with a successful cutting experience.

Applications

The speed, precision and efficiency of laser cutting has landed it in multiple different industries performing for many different applications. High-powered lasers are found in industrial settings, both in metal and non-metal factories. The speed of laser cutting lends itself to creating prototypes in many fields such as architecture, model making and miniatures (as we do!). The precision lends itself to etching electronic circuit boards and custom engraving projects like jewelry or other small arts and crafts. Laser cutting is used in the mass production of fashion items and clothes. Essentially, if there is a need for some sort of engraving or quick cutting function, laser cutting can be a viable option.

Getting Started

In conclusion, laser cutting provides a blend of precision and creativity to provide a level of versatility that is unmatched in the manufacturing world. Laser cutting empowers makers, both hobbyists and professionals alike, to create intricate designs with endless possibilities. Good news is that you’re in the right place! Here on LaserCutHub we have all sorts of educational posts and projects to research and learn. Delve into the world of software and modeling with some background on SolidWorks, LibreCAD and LightBurn. Finally, you can look at some of our free test projects to build or subscribe to the free weekly newsletter! Happy Cutting!