What is laser cutting and how does it differ from laser engraving?

what is laser cutting

From simple DIY projects at home to highly skilled applications in industries, laser engraving is taking the world by storm. The term “LASER” is an acronym for “Light Amplification by Stimulated Emission of Radiation.” Laser cutting and engraving are popular because you can use the laser to cut through quite a number of materials and in a very short time too. the precision of laser cutters also makes it an easy choice for various applications.

So, what is laser cutting and how does it differ from laser engraving?

Simply put, laser engraving is the process of marking or engraving various materials by using laser cutters/engravers. Laser engraving is not similar to laser cutting. In laser engraving, the engraver works by removing some material from the surface up to a certain depth thereby leaving behind an artistic pattern. Laser marking is another technique of laser engraving and it works by discoloring the surface without removing any of the material. On the other hand, laser cutting is the process of slicing materials with the help of a laser cutter. However, all these techniques use a laser beam from a laser machine.

The main advantages of laser engravers/cutters

  • Laser cutting offers unparalleled positional accuracy and precision
  • A laser cutter can be used to achieve very complex shapes
  • You can use laser cutters to achieve awesome designs with very little workpiece degradation
  • Laser cutters are a cost-effective way of achieving cuts and engravings on materials
  • You can choose to either cut, drill or engrave the material as per your needs
  • Laser cutters give a polished finish on the surfaces cut
  • There is very little thermal stress zone
  • Laser cutting can be used on a variety of materials

The history of laser engraving/cutting

Lasers were first used by physicists for scientific research in the 1960s following the invention of colored laser beams. In 1965, the Western Engineering Research Center became the first to use a laser beam for purposes of cutting. Up until this time, thousands of diamond dies were used in the manufacture of electrical connections and this required the piercing of the dies and then resizing them into thin wires. It was a slow and laborious process that would take at least 24 hours. The laser was introduced as an alternative to diamond dust or metal drills.  In the year 1967, Houldcroft came up with the idea of adding a laser cutting nozzle that used an oxygen pressure chamber in order to help in the focusing other laser beam and the rest, as they say, is history. By 1969, the technology had already developed so much that Boeing introduced laser cutters in their production lines. The laser cutters came in handy when cutting hard materials like titanium, ceramic and Hastelloy.

Decades after the invention of laser cutting technology, laser cutting, and laser engraving have evolved and are now in use in almost all industries. And unlike the 60s, the modern-day laser machine is not only meant for cutting or engraving metal but also plastic, paper, wood, textiles, ceramic, cardboard, etc. This is possible because the laser machines now have higher quality laser beams which can achieve higher precision. The applications for laser cutting are endless. For instance, the laser cutters can be used to cut photovoltaic cells in solar panels for industrial use or they can be used to create aesthetically appealing coasters for domestic use.

How does the laser cutter work?

The laser machine sends an intense laser beam via a laser resonator which then reflects on to a surface through a system of mirrors within the cutting head. In the cutting head, the laser beam is focused via a lens in order to make it an extremely thin and concentrated beam. The active laser medium can be;

  • A gas mixture – oxygen is the most commonly used gas but a mixture composing of carbon dioxide can also be used
  • Fiber – glass fibers are the most common laser medium
  • A solid – crystal is the most common solid medium used in lasers

The resonator creates energy either through an electric charge or from the light generated by diodes. As the resonator generates lasers, the beam is guided by mirrors in a specific direction and the lens focuses the light to give it precision and amplification. This focusing enhances the cutting power of the laser beam. Most laser machines have capacitive height control which helps to create and maintain an accurate space between the nozzle and the workpiece. This gap is what determines the quality and depth of the cut. A laser cutter achieves the cut through vaporizing, melting or burning of the surface. Compressed gases like nitrogen and oxygen also exit from the nozzle and thereby flush any molten debris from the surface. Laser cutters can be either;

  • Galvanometer systems – these systems place the laser beam at several angles on the material and this is achieved by angled mirrors. Galvanometer systems are used more for engraving purposes because they do not provide clean cuts. A laser beam is usually placed at the center of the device and it is then oriented with angled mirrors in order to cut the material in bias.
  • Gantry systems – gantry systems place the laser beam perpendicular to the material being cut. This is achieved through a plotter with three mirrors; one of which is a fixed mirror and the other two are mobile.

Laser cutters may be built in a similar way but they are different because each is built with a unique power range. This means that different laser cutters are ideal for different types of materials and thicknesses. There are three main categories of laser cutters with unique characteristics and functions. The table below illustrates this more clearly;

Laser cutter type Mode of operation Characteristics Materials to use
CO2 Laser A gas that is a mixture of carbon dioxide and nitrogen with hydrogen with either xenon or helium Inexpensive laser cutter and it can cut thin sheets Wood, plastics, leather, foams, and acrylic
Fiber lasers The laser beam is amplified through glass fibers Commonly used for placing logos on products, making custom products and barcoding. Metals and plastics
Neodymium lasers Uses neodymium-doped crystals They have a small wavelength which allows them to cut through thick materials Metals, plastic, and ceramics

Materials ideal for laser cutting

The options for materials that can be laser engraved are endless. But laser cutting is quite intense and not every material can handle it. This is why laser cutting is mostly used on only four materials namely;

  • Medium-density fiberboard
  • Cardboard
  • Plywood
  • Acrylic

Medium-density fiberboard (MDF)

MDF is an engineered wood that is made by breaking down of softwood or hardwood residuals into wood fibers and then combining the fibers with a resin binder to form panels. MDF is typically denser than plywood and it is commonly used as a building material. MDF comes in various colors and it is homogenous in that it has the same properties across its dimensions (isotropic). Cutting MDF with a laser cutter doesn’t result in splinters or splits. Since MDF doesn’t have fibers, there is no specific direction that one must follow when cutting. MDF can be used to make prototypes, ornaments, puzzles, furniture, coasters, etc.

Cardboard

Cardboard is a rigid and yet light-weight material that is made by attaching several sheets of paper that are corrugated and wavy. The term cardboard is loosely used to refer to all heavy-duty papers of various thicknesses. Cardboard if not only inexpensive but also very easy to find. This makes cardboard a great material for testing out complex designs before using the laser cutter on more expensive materials. But in addition to making prototypes, you can also use cardboards for making other intricate designs including business cards, kids projects, package designs, and various arts.

Plywood

Plywood is a natural sheet material that is manufactured by gluing thin plies of wood veneer together. Plywood is loved by manufacturers because of its flexibility and resistance. The precise nature of the laser cutter gives a neat finish when laser cutting plywood so there is no need to worry about the quality of the finished edges. Laser cutting of plywood can, therefore, be used to create designs on furniture. Plywood can also be an excellent engraving base for symbols and pictures.

Acrylic

This is a type of plastic that comes in various brands depending on the manufacturer. Common brands include Plexiglas, Lucite, Perspex, Acrylate, and Optix. Acrylic has a glossy surface and this makes it quite attractive. It also comes in different thicknesses and colors including a transparent or translucent shade. Acrylic can also have two tones with a top layer that has a different color from the base color. Acrylic is most ideal of high-contrast laser cutting e.g. in making of plaques, signs, and panels. Acrylic is also quite brittle and laser cutting is the safest way to drill holes without damaging the material.