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Manufacturing Process: Laser Cutting
Transcript of Manufacturing Process: Laser Cutting
cutting was used in 1965
to drill holes in diamond
dies. The machine was made by
Western Electric Engineering
Research Center. In 1967, the British pioneered
laser-assisted oxygen jet cutting
for metals. Later, around the early 1970's
this technology was out into production to cut titanium for aerospace applications. At about the same time, CO2
lasers were created to cut non-
metals, such as textiles. General
Info. Laser cutting is a technology
that uses a laser to cut materials. It is typically used for industrial
manufacturing applications, but
is starting to be used be schools
and small businesses also. It works by directing the output of a
high-power laser, by computer, at the material to be cut. The material then either melts, burns,
vaporizes away, or is blown away by
a jet of gas, leaving a high-quality surface
finish on the edge. Types There are three main types of lasers used in laser cutting... The CO2 laser is suited for cutting,
boring, and engraving. CO2 Lasers There are many variants of CO2 lasers
including fast axial flow, slow axial flow,
transverse flow, and slab. CO2 lasers are commonly
pumped by passing a current
through the gas mix (DC-excited)
or using radio frequency energy
(RF-excited). The RF method is newer and
has become more popular. Since
DC designs require electrodes inside
the cavity, they encounter erosion
and plating. RF resonators have
external electrodes and are not prone
to these problems. In addition to the power source, the type of gas flow can affect performance as well. In a fast axial flow resonator, the mixture of gases
is circulated at high velocity by a turbine or blower.
Transverse flow lasers circulate the gas mix at a lower
velocity, requiring a simpler blower. Slab resonators have a static gas field that requires no pressurization
or glassware, leading to savings on these products. Nd Lasers Neodymium lasers is the long name.
They are used for primarily boring and jobs
where high energy but low repetition is
required. Nd-YAG Lasers Short for neodymium yttrium-aluminum-garnet lasers.
They are used with very high power in boring and engraving.
Very high-energy pulses Most
Popular! High-energy pulses Low repetition
speed (1kHz) Laser Microjet This type of laser sub-category
is a water-jet guided laser in which
a pulsed laser beam is coupled into
a low-pressure water jet. Performs basically all
of the same functions. Advantages over regular laser cutting
include its ability to remove debri and
cool material. It also moves at high dicing speeds and can cut in practically any direction. Process First, the laser must be generated
by stimulating a lasing material
through electrical discharges or
lamps within a closed container. As the material is being stimulated, the beam is reflected internally by means of a partial mirror. The beam is reflected until it achieves
sufficeint energy to escape as a stream
of light. Mirrors and other fiber optics are typically used to direct the light to a lens, which focuses the laser onto the work zone. The beam is generally less than 0.0125 in.
in diameter. Either a pierce or a straight cut is done depending on where the initial cut is going to be made. If the cut is starting along an edge there are no precautions needed. If the cut needs to start in the middle of a part, a pierce is done to slowly make a hole in the material. Machine
Configurations There are generally three different configurations in industrial laser cutting machines: moving material, hybrid, and flying optics. These refer to the way that the laser beam is moved over
the material to be cut/processed. Moving material lasers have a stationary cutting head and move the material under it. It requires fewer optics, moving the workpiece, and is the slowest of the three. Hybrid lasers provide a table which moves in one axis and the head which moves on a shorter axis. This makes a constant beam delivery and permits a simple beam delivery system. It results in reduced power loss. Flying optics lasers feature a stationary table with a
cutting head that moves over the workpiece in all directions.
The size of the workpiece is not an issue, so these machines can work with essentially anything. It is also the fastest
of the three configurations. Methods Vaporization
Cutting Melt and Blow Thermal Stress
Cutting Also called fusion cutting, this method uses high-pressure gas to blow molten material from the cutting area. First, the material is heated to its melting point then a gas jet blows molten material out of the work area. Used with metals. In this type, the focused beam heats the surface of the material to its boiling point and generates a keyhole. The keyhole leads to a sudden increase in adsorptivity quickly deepening the hole. As the hole deepens and the material boils, generated vapor erodes the molten walls blowing eject out, enlarging the hole. Used with wood, carbon, thermoset plastics, and other non-melting material. Also called flame cutting, it acts like an oxygen torch, but with a laser as the ignition source. Mostly used for cutting carbon steel and very thick steel plates with relatively little laser power. A beam is focused on the surface of a brittle material causing localized heating and thermal expansion. This results in a crack that can then be guided by the moving beam. Usually used in cutting glass. Advantages Disadvantages Easier workholding
Reduced chance of warping
Uses less energy than plasma
Also, lasers can be up to thirty
times faster than standard sawing. High power consumption
Cannot cut through very thick materials
Certain materials also cause issues Types of