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How Does A Laser Cutter work?


How Does A Laser Cutter work?

Are you new to the world of laser cutting and wondering how laser cutting machines work? Laser technologies are very complex, and can be explained in equally complicated ways.

This post aims to explain the basics of laser cutting functionality in Layman’s terms.

Unlike a household light bulb that produces bright light to travel in all directions, a laser is a stream of invisible light (usually infrared or ultraviolet) that is amplified and concentrated into a narrow straight line.

This means that compared to ‘normal’ light, lasers are much stronger.

Laser cutting and engraving machines are named after the source of the types of lasers used (where the light is first generated), the two most common types of laser cutters are CO2 and Fiber Lasers.

Let’s start with the most widely used, CO2 laser cutters.

The Brains: Laser Cutting Design Software

An image showing laser cutting design software in use

Laser cutting design software serves as the “brains” behind the operation of laser cutters, translating creative designs into precise, executable cutting paths.

This software is pivotal in the laser cutting process, bridging the gap between digital design and physical creation. It allows designers and engineers to meticulously plan and visualize the end product before any material is cut, ensuring accuracy and efficiency.

At its core, laser cutting design software functions by allowing users to import or create designs within the program.

These designs can range from simple shapes to complex, intricate patterns. The software then interprets these designs into digital commands that guide the laser cutter’s CNC movements.

One of the key features of this software is its ability to work with vector graphics.

Vector graphics are essential for laser cutting because they can be scaled without losing quality, ensuring that the design remains sharp and clear, regardless of size.

This is particularly important for projects that require high precision, such as intricate jewellery designs or detailed engineering models.

How Does A CO2 Laser Cutter Work?

A CO2 laser tube installed in a CO2 laser cuttere

Modern CO2 laser cutting machines usually produce the laser beam in a sealed glass tube which is filled with a gas mixture, predominantly carbon dioxide (CO2). A high voltage flows through the tube and reacts with the gas particles, increasing their energy, in turn producing light.

A product of such strong light is heat, heat so strong it can vapourise materials that have melting points of hundreds of °C.

Mirrors & Focusing

At one end of the tube is a partially reflective mirror, and the other end, is a fully reflective mirror.

The light is reflected back and forth, up and down the length of the tube, this increases the intensity of light as it flows through the tube.

Eventually, the light becomes powerful enough to pass through the partially reflective mirror. From here, it is guided to the first mirror outside of the tube, then to a second, and finally to the third.

These mirrors are used to accurately deflect the laser beam in the desired directions.

An example of a laser cutters mirrors in action

The final mirror is located inside the laser head and redirects the laser vertically through the focus lens to the working material.

The focus lens refines the path of the laser, ensuring it is focused on a precise spot.

The laser beam is typically focused from around 7mm diameter down to approximately 0.1mm depending on the distance to the material.

It is this focusing process and the resulting increase in light intensity that allows the laser to vapourise such a specific area of the material’s surface to produce extremely precise cutting results.

Moving The Laser with CNC Systems

The CNC (Computer Numerical Control) system allows the machine to move the laser head in different directions over the work bed and workpiece.

By working in unison with the mirrors and lens the focused laser beam can be quickly moved around the machine bed to create different shapes without any loss in power or accuracy.

The incredible speed at which the laser can switch on and off with every pass of the laser head allows it to engrave some incredibly intricate designs.

What Materials Can Be Cut/Engraved With A CO2 Laser Cutter?

An example of finished engraved dog collar tags

CO2 laser cutters can work with a range of materials, however, which is the best for your needs will ultimately depend on your requirements. We’ve got an extremely extensive guide on how to choose a laser cutter here.

However, CO2 lasers are primarily used to cut and/or engrave the following types of materials:

  • Acrylic
  • Wood
  • Paper
  • Leather
  • Metals (typically for engraving only when anodised or powder coated or engraving bare metals with a specialist marking compound)

How Does A Fiber Laser Cutter Work?

Fiber laser cutters are the newest type of laser in the industry, following many of the same principles as CO2 lasers, but a few key details make them much more powerful than CO2 laser cutters and able to work with thicker materials.

An image showing a fiber laser cutting through metal

Fiber technology has continually advanced across so many industries and has been optimised so much that light can now even be used to transport data, typically used in applications such as high-speed broadband internet.

If you consider fiber optic broadband compared to cable or DSL, you can instantly draw comparisons between them, one of the most apparent differences being speed.

You can begin to use this comparison to represent fiber and CO2 lasers.

That’s not to say CO2 machines are something of the past, just that there is now an option of much higher power and alternative laser wavelength.

The power and wavelength are ideal for engraving and cutting uncoated metals such as carbon and stainless steel, brass, and copper. You can learn more about what fiber laser cutters are here.

Some of the benefits of fiber laser cutters are:

  • Operating costs are considerably lower than CO2 laser cutters
  • They can cut various thick metals
  • Fiber machines are incredibly fast compared to CO2
  • They require less maintenance than CO2 laser machines
  • Fiber lasers are extremely precise

An product image of an industrial sized laser cutter

Directing The Beam

The light is generated in and injected into a fiber optic cable cable, then reflected through a narrow cavity that keeps the beam incredibly straight.

Adjustable mirrors aren’t needed to direct the beam, meaning you don’t have to re-align optics regularly.

Due to the straightness of the laser beam, it can be concentrated to accurately focus on the smallest areas, making it perfect for laser cutting intricate designs and complex shapes, this is known as it’s kerf.

Nufern Inc. provide a compelling explanation into the raw physics of this process.

Fiber engraving machines can mark uncoated metals with ease using as little as 20W of power, and at higher powers can cut through many types of metals and material thickness.

Instant reactions within the cable mean a fiber laser is ready to work as soon as it is switched on.

What Materials Can Be Cut With A Fiber Laser Cutter?

An example of cut and engraved stainless steel produced by a fiber laser cutter

Fiber laser cutting machines are predominantly used in industrial manufacturing to cut a wide variety of metals, of various thickness, including reflective materials. These include:

  • Mild Steel
  • Stainless Steel
  • Aluminium
  • Titanium
  • Brass & Copper

Because of their wavelength, fiber laser engraving machines are also mostly able to engrave and mark metals without the use of a marking compound.

Summing Up

From the precision and versatility of CO2 lasers, ideal for a wide range of non-metallic materials, to the power and efficiency of fiber lasers, capable of cutting through thick metals with ease, the principles are similar, but the choice of laser technology depends on the specific needs of your project.

To compare CO2 vs fiber lasers side by side and find out which is suitable for you, we recommend reading this article next.

If you have any questions about how the HPC Laser range of machines work, please just get in touch with the team today!

For information about laser markers and engravers see What is Laser Marking?

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