Laser cutting is a technology that uses a
laser to cut materials, and is typically used for industrial manufacturing
applications, but is also starting to be used by schools, small businesses, and
hobbyists. Laser cutting works by directing the output of a high-power laser
most commonly through optics. The laser optics and CNC (computer numerical
control) are used to direct the material or the laser beam generated. A typical
commercial laser for cutting materials would involve a motion control system to
follow a CNC or G-code of the pattern to be cut onto the material. The focused
laser beam is directed at the material, which then either melts, burns,
vaporizes away, or is blown away by a jet of gas, leaving an edge with a
high-quality surface finish. Industrial laser cutters are used to cut
flat-sheet material as well as structural and piping materials.
Methods
There are many different methods in cutting
using lasers, with different types used to cut different material. Some of the
methods are vaporization, melt and blow, melt blow and burn, thermal stresscracking, scribing, cold cutting and burning stabilized laser cutting.
Vaporization
cutting
In vaporization cutting the focused beam
heats the surface of the material to boiling point and generates a keyhole. The
keyhole leads to a sudden increase in absorptivity quickly deepening the hole.
As the hole deepens and the material boils, vapor generated erodes the molten
walls blowing ejecta out and further enlarging the hole. Non melting material
such as wood, carbon and thermoset plastics are usually cut by this method.
Melt and
blow
Melt and blow or fusion cutting uses
high-pressure gas to blow molten material from the cutting area, greatly
decreasing the power requirement. First the material is heated to melting point
then a gas jet blows the molten material out of the kerf avoiding the need to
raise the temperature of the material any further. Materials cut with this
process are usually metals.
Thermal
stress cracking
Brittle materials are particularly sensitive
to thermal fracture, a feature exploited in thermal stress cracking. A beam is
focused on the surface causing localized heating and thermal expansion. This
results in a crack that can then be guided by moving the beam. The crack can be
moved in order of m/s. It is usually used in cutting of glass.
Stealth
dicing of silicon wafers
The separation of microelectronic chips as
prepared in semiconductor device fabrication from silicon wafers may be
performed by the so-called stealth dicing process, which operates with a
pulsed Nd:YAG laser, the wavelength of which (1064 nm) is well adopted to the
electronic band gap of silicon (1.11 eV or 1117 nm).
Reactive
cutting
Also called "burning stabilized lasergas cutting", "flame cutting". Reactive cutting is like oxygen
torch cutting but with a laser beam as the ignition source. Mostly used for
cutting carbon steel in thicknesses over 1 mm. This process can be used to cut
very thick steel plates with relatively little laser power.
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