Home > Metal & laser cutting tips > Laser cutting vs. plasma cutting
Standard metal cutting processes: laser cutting vs. plasma cutting
Laser manufacturing activities currently include cutting, welding,
heat treating, cladding, vapor deposition, engraving, scribing,
trimming, annealing, and shock hardening. Laser manufacturing
processes compete both technically and economically with conventional
and nonconventional manufacturing processes such as mechanical
and thermal machining, arc welding, electrochemical, and electric
discharge machining (EDM), abrasive water
jet cutting, plasma cutting, and flame
cutting.
Plasma (arc) cutting was developed in the 1950s for
cutting of metals that could not be flame cut, such as stainless
steel, aluminum and copper. The plasma arc cutting process uses
electrically conductive gas to transfer energy from an electrical
power source through a plasma cutting torch to the material
being cut. The plasma gases include argon, hydrogen, nitrogen
and mixtures, plus air and oxygen.
Normally, a plasma arc cutting system has a power supply, an
arc starting circuit, and a torch. The power source and arc
starter circuit are connected to the cutting torch through leads
and cables that supply proper gas flow, electrical current flow,
and high frequency to the torch to start and maintain the process.
The arc and the plasma stream are focused by a very narrow nozzle
orifice
The temperature of the plasma arc melts the metal and pierces
through the workpiece while the high velocity gas flow removes
the molten material from the bottom of the cut, or the kerf.
In addition to high energy radiation (Ultraviolet and visible)
generated by plasma arc cutting, the intense heat of the arc
creates substantial quantities of fumes and smoke from vaporizing
metal in the kerf..
The table that follows contains a comparison of metal cutting
using the CO2 laser cutting process and plasma cutting
process in industrial material processing.
Fundamental process differences
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Method of imparting energy
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Light 10.6 µm (far infrared range)
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Gas transmitter
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Source of energy
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Gas laser
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DC power supply
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How energy is transmitted
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Beam guided by mirrors (flying optics); fiber-transmission
not
feasible for CO2 laser
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Electrically charged gas
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How cut material is expelled
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Gas jet, plus additional gas expels material
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Gas jet
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Distance between nozzle and material and maximum permissable
tolerance
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Approximately 0.2" ± 0.004", distance sensor,
regulation and Z-axis necessary
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0.010" to 0.02"
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Physical machine set-up
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Laser source always located inside machine
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Working area, shop air and plasma torch
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Range of table sizes
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8' x 4' to 20' x 6.5'
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8' x 4' to 20' x 6.5'
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Typical beam output at the workpiece
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1500 to 2600 Watts
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Not applicable to this process
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Typical process applications and
uses
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Typical process uses
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Cutting, drilling, engraving, ablation, structuring,
welding
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Cutting
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3D material cutting
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Difficult due to rigid beam guidance and the regulation
of distance
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Not applicable to this process
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Materials able to be cut by the process
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All metals (excluding highly reflective metals), all
plastics, glass, and wood can be cut
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All metals can be cut
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Material combinations
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Materials with different melting points can barely
be cut
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Possible materials with different melting points
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Sandwich structures with cavities
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This is not possible with a CO2 laser
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Not possible for this process
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Cutting materials with liminted or impaired access
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Rarely possible due to small distance and the large
laser cutting head
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Rarely possible due to small distance and the large
torch head
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Properties of the cut material which influence processing
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Absorption characteristics of material at 10.6 µm
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Material hardness is a key factor
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Material thickness at which cutting or processing is
economical
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~0.12" to 0.4" depending on material
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~0.12" to 0.4"
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Common applications for this process
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Cutting of flat sheet steel of medium thickness for
sheet metal processing
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Cutting of flat sheet and plate of greater thickness
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Initial investment and average operating
costs
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Initial capital investment required
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$300,000 with a 20 kW pump, and a 6.5' x 4'
table
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$120,000+
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Parts that will wear out
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Protective glass, gas
nozzles, plus both dust and the particle filters
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The cutting nozzles and electrodes
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Average energy consumption of complete cutting system
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Assume a 1500 Watt CO2 laser:
Electrical power use:
24-40 kW
Laser gas (CO2, N2, He):
2-16 l/h
Cutting gas (O2, N2):
500-2000 l/h
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300 amp Plasma
Electrical power use:
55kW
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Precision of process
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Minimum size of the cutting slit (kerf width)
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0.006", depending on cutting speed
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0.002"
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Cut surface appearance
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Cut surface will show a striated structure
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Cut surface will show a striated structure
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Degree of cut edges to completely parallel
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Good; occasionally will demonstrate conical edges
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Fair, will demonstrate non-parallel cut edges with
some frequency
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Processing tolerance
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Approximately 0.002"
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Approximately 0.02"
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Degree of burring on the cut
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Only partial burring occurs
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Only partial burring occurs
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Thermal stress of material
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Deformation, tempering and structural changes may occur
in the material
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Deformation, tempering and structural changes may occur
in the material
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Forces acting on material in direction of gas or water
jet during processing
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Gas pressure poses
problems with thin
workpieces, distance
cannot be maintained
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Gas pressure poses problems with thin
workpieces, distance cannot be maintained
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Safety considerations and operating environment
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Personal safety
equipment requirements
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Laser protection safety glasses are not absolutely
necessary
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Protective safety glasses
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Production of smoke and dust during processing
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Does occur; plastics and some metal alloys may produce
toxic gases
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Does occur; plastics and some metal alloys may produce
toxic gases
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Noise pollution and danger
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Very low
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Medium
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Machine cleaning requirements due to process mess
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Low clean up
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Medium clean up
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Cutting waste produced by the process
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Cutting waste is mainly in the form of dust requiring
vacuum extraction and filtering
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Cutting waste is mainly in the form of dust requiring
vacuum extraction and filtering
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Other metal cutting processes
If you would like more information about our laser cutting
services, please use our contact
form or email us at info@teskolaser.com.
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