How Does Laser Cutting Work?

Laser cutting is typically the first fabrication process within metalwork projects, and can be summarised as:

• A high-intensity beam of infrared light is generated by a laser.
• The beam is focused onto the surface by different means dependent on the laser. A co2 Laser for example uses focusing lenses; whereas a Fiber Laser delivers the beam through a fibre-optic cable.
• This focused beam heats the material to the point of it melting, burning or vaporising to a diameter typically smaller than 0.5mm.
• Some commercial lasers are capable of cutting metallic and some non-metallic materials to tolerances of 0.1mm (and even tighter tolerances are capable with specialist lasers).
• An assist gas is then employed to clear the area of molten or burned material.
• In some cases, the gas that is employed can accelerate the cutting process through a chemical reaction. For example, the oxidation process which occurs by laser heating generates its own heat, which greatly adds to the efficiency of the process. This is why thicker steels are generally cut in a jet of pure oxygen.¹
• Following a design/pattern that is programmed into the machine, the laser is moved across the workpiece which can be done by mechanically moving the sheet on a CNC X-Y table. There are also ‘Hybrid’ systems which move the material in one axis and the laser in another and fully robotic systems available, among others.

Evolution of the Laser Cutter

Although now a highly common practice across a number of sectors such as machinery, transport and even art – laser cutting has only been around for a relatively short amount of time.

While working at the Bell Laboratories during World War II, physicist Charles Townes worked on several projects including radar-assisted bombing systems, and microwave generators in the 1950s following a theory from Einstein created the “MASER” (Microwave Amplification by Stimulated Emission of Radiation).

Charles Townes

This was used primarily for scientific research, not so much for industrial applications – but by studying the equations for amplifying radiation, realised this would be made easier another way – with short waves rather than far-infrared waves.²

By joining forces with his brother-in-law Arthur Schwalow and Gordon Gould (a graduate student at Columbia University) developed an optical resonator that amplifies light, called a “LASER” (Light Amplification by Stimulated Emission of Radiation).

Although understanding the principles, the three could not build a working prototype.

In 1960, it was Thomas Maiman who made the first synthetic ruby laser, which produced a perfectly straight red laser beam.

In 1963, Elias Snitzer invented the Fiber Laser, although it would take almost another twenty years of development for them to be ready for commercial production – this then enabled CO2 lasers to take the forefront of the industry during this decade.

During the 1960s, Kumar Patel of (at this time) Bell Labs began fundamental research in laser action of pure rare gases, which led him to discover laser action in Carbon Dioxide in 1963.

Kumar Patel

In 1964, Patel invented the nitrogen carbon dioxide, or CO2, laser – this being the first gas laser to produce a continuous stream of high-power radiation.

Prior to laser cutting being used to cut parts out of metal, it was used as a drilling tool in 1965.

Co2 lasers with power exceeding 1000 watts became possible by 1967 with further advancements coming by way of a gas-assisted laser cut in the same year.

Peter Houldcraft, then Deputy Scientific Director at TWI (The Welding Institute), realised that combining a focused laser beam and an oxygen assist gas could greatly improve the precision and speed offered by thermal cutting processes.

Houldcroft designed a ‘laser cutting nozzle’ whereby the oxygen pressure chamber provides the co-axial reactive assist gas stream in the area where the laser beam is focused.

1979 became the year Italian company Prima Industrie invented the first 3D laser-cutting process with a 5-axis rotation system.

In 1985, more than two decades after Snitzer had first demonstrated fibre lasers, the technology began to rapidly progress.

David Payne at the University of Southampton, tried ‘doping’ fiber cores with rare-earth elements to make fiber lasers.

Payne began doping with neodymium; Emmanual Desurvire of Bell Labs proved erbium to be a better element, while David Hanna of Southampton found ytterbium to be an attractive ion for use in fibre lasers.

Through the early 1990s fibre experiments showed that ytterbium worked very well in a fibre configuration, with this becoming the most active element of choice for fibre lasers today.³

Fiber lasers did not become a production reality until 2010. Moving to today, and although relatively new compared to co2, fibre lasers are stamping themselves as the laser of choice for cutting flat metal sheets and plates.

It took five years for fibre lasers to reach 4kw, with co2 lasers taking four times as long to achieve this; ten years for fibre lasers to reach 10kw to 12kw, which co2 lasers never have achieved; commercial fibre lasers even now reach levels of 20kw.

The Future of Laser Cutting

The global laser market continues to grow with the fibre laser market poised to grow by $8.33 billion during 2020-2024, progressing at a CAGR (compound annual growth rate) of 11%,⁴ with gas lasers expected to have a CAGR of 9.4% over the next decade.⁵

Fiber lasers, as can be seen by the above figures will continue to dominate the market for some time; but as can be seen from previous industry trends, rapid advancements in technology mean things can change in a short period of time.

One recent advancement, the Direct Diode Laser (DDL), is one to keep an eye on.

This works by eliminating the doped fibre system used in fibre laser technology, with claims this makes the DDL more efficient due to eliminating the middle process.

It is also said that DDLs are the smallest and most reliable laser source, all while having an incredibly high-quality beam.

However, at present they are only available at lower power levels; until recently only reached levels of 2000 watts, but today this platform has reached 8000 watts.

Another advancement that will over the next few years become the norm within the industry, is automation.

ADS is the premier metal laser cutting, folding, fabrication, finishing and assembly. Providing bespoke to volume solutions.

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