LASER CUTTING
Laser cutting: Thicker, faster cuts offering lower cost per part
www.lasersystemseurope.com/applications/cutting
An overview of laser cutting and some of the technology developments made in recent years
Cutting is one of the most common and widely known applications of materials processing lasers. It is used widely in industries such as automotive, aerospace, solar, electronics, textiles, jewellery and medical device manufacturing. The process comprises a
laser beam – the power and wavelength of which depends on the thickness and type of material being cut – being directed through a set of optics and manipulated in a pattern over a workpiece via computer numerical control (CNC). The beam is focused to hit the workpiece in a single spot typically measuring less than 500µm in diameter, with the intensity of the beam causing the material to heat up. The material then either burns, melts, vaporises or is blown away by a jet of gas to leave a high-quality finished edge. Once the beam completely penetrates through to the other side of the material, the cutting process has begun. Many laser cutting
applications are assisted by either an active or inert gas delivered coaxially through the same nozzle as the beam. Oxygen is the standard active assist gas used, for example, when cutting mild and carbon steels, while nitrogen is the
typical choice of inert gas when cutting, for example, stainless steels, aluminium and its alloys. When cutting with oxygen, the material is burned and vapourised after being heated up to ignition temperature by the laser beam. The reaction between the oxygen and the metal creates additional energy in the form of heat, which supports the cutting process. The liquid metal is then removed from the kerf by the shear force of the oxygen jet. On the other hand, cutting with an inert gas such as nitrogen – also referred to as clean or high-pressure cutting – instead involves the material being melted solely by the laser. The melted material is then blown out of the cut kerf via the force of the gas jet.
What are the advantages of laser cutting? Laser cutting is often favoured over alternative cutting methods such as plasma, waterjet, flame and mechanical cutting due to its exceptional speed, flexibility, repeatability, precision, efficiency, affordability and quality, as well as its minimal post-processing requirements. Being a non-contact process,
laser cutting usually results in little workpiece distortion or warping. No hard tools are required, meaning there is no need for tool storage, changeover or sharpening – reducing setup requirements and costly downtime between jobs, as well as inefficiencies throughout longer jobs. Being a highly automatable process simplified via CNC manipulators and robots, users are left with the tasks of
44 LASER SYSTEMS EUROPE THE 2023 GUIDE TO LASER SYSTEMS
programming the machines and loading and unloading the material accordingly. The highly focused spot
results in a small heat-affected zone, resulting in clean edges, precise cuts and the rest of the workpiece only being subject to minimal thermal stresses. Consequently, the technology can be used to cut intricate shapes, free of burrs, enabling parts to be nested close together in the sheet of material being cut. This provides the ability to either reduce or even eliminate scrap entirely. Laser cutting can be used
to process a wide range of materials, up to hundreds of millimetres in thickness. These
“Laser cutting is often favoured over alternative cutting methods due to its exceptional speed and flexibility”
include many metals common to industry – copper, brass, aluminium, mild steel, stainless steel, titanium etc. – as well as non-metal materials such as plastic, leather, ceramic, wood, laminate, acrylic, cork, foam, wax, textiles and paper.
What lasers are used for cutting? Two types of laser commonly used for cutting applications are CO2 lasers and fibre lasers, each presenting their own set of advantages and disadvantages. CO2 lasers can be found
at wavelengths 9.3, 10.25 and 10.6µm, and at powers typically ranging from tens to hundreds of watts. They carry the advantage of being able to cut a wide range of materials with exceptional edge quality, and particularly excel at cutting non-metals. They also perform well in terms of piercing speed, cutting speed and edge quality when processing thicker (>8mm) sheets of mild and stainless steel. The downsides of CO2 laser systems are that they require more servicing and
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