Laser cutting is a technology that harnesses the power of laser to cut materials precisely and accurately as per required specifications. It is very useful in large industrial and commercial applications but lately has been successfully used in small industries, businesses and even hobbyists. The process involves harnessing and directing the power of laser through optics which together with CNC or Computer Numerical Control manoeuvre the laser over the material. The focussed beam of laser then melts, vaporizes or burns away the material on which it is targeted leaving behind a smooth and polished finish. Materials of any size or shape can be cut with laser.
The first commercially produced laser cutting machines were made by Western Electric Engineering Research Centre in 1965 and were primarily used to drill holes in diamond dies. In 1967, laser-assisted oxygen jet cutting on metals was pioneered in Britain. Innovations led to laser machines that could cut titanium in the aerospace industry followed by CO2 lasers that were used to cut non-metals such as textiles. This was a path breaking invention as such lasers could overcome the thermal conductivity of metals.
Laser beam generation is a complex process. A lasing material is stimulated within a closed container by electrical discharges and resultant laser beam is reflected internally through a partial mirror. Energy is built up inside and released as a ray of monochromatic coherent light. This is then directed on to mirrors or fibre optics and the resultant coherent light is focussed on the material to be worked on. It is a high powered beam of light with a diameter that is less than 0.0125 inches. Depending upon the material to be cut, the light beam diameter can be brought down to a pinpoint 0.004 inches. The cutting process starts with a hole being drilled in the material with laser and then moving across the material. Typically, a hole on a 0.5 in steel plate can be done in 5 to 15 seconds. That is the power of a laser cutting machine.
What makes laser technology a highly effective option over other cutting equipment is its computer controlled precision and accuracy in industrial applications. An example will illustrate this better. If you have seen home security systems supplied by One-tech Security in Melbourne Australia, you will find that the alarm devices are very small in size especially the infrared sensors and other warning devices. All these have been fabricated with laser cutting machines as they are too small and delicate to be done manually without substantial margins of errors. Once alarm installation in Melbourne has been carried out, the devices are so reliable that they offer years of trouble free service, all thanks to technologically advanced laser cutting machines.
Laser cutting comprises of different methods depending on the material that is being used for. These include –
Melt and blow – Also known as fusion cutting, it uses high pressure gasses to blow liquidised metal from the cutting area. The metal is first heated to melting point and then blown away by a gas jet. Only metals can be subjected to this method.
Thermal stress cracking – This is used when operating on brittle materials such as glass which is sensitive to thermal cracking. The laser is focussed on the surface which heats up the area leading to thermal expansion. The brittle material cracks up and this is guided by moving the beam along required cutting lines.
Vaporization cutting – Focussed beam of laser light heats up the target area bringing the material to boiling point and creating a keyhole. As the hole deepens the vapour that is generated blows on the molten walls further making the hole bigger. This application is perfect for non-metal materials such as wood, carbon and plastics.
Reactive cutting – It is similar to an oxygen torch cutting but has a laser beam at the end. It is very useful for cutting carbon steel over 1mm thick and other thick steel plates.
These are some of the aspects of laser cutting in a nutshell.