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Cutting Method Comparison Waterjet vs. Laser vs. Plasma |
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With the number of CNC cutting methods available to today's fabricator, including laser, plasma and waterjet based systems, making the correct choice between these technologies can sometimes be daunting. However, when application requirements such as part accuracy, process speeds and material demands are compared against the abilities of these sometimes competing methods, a careful evaluation will often lead to selecting the best cutting method. Typical criteria used for most process evaluations include the following: |
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Materials To Be Processed Range Of Material Thickness Part Accuracy Desired Production Rate Desired |
Target Market For Parts Operator Skill Requirements Capital Costs Operating Costs |
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While a laser cutter can produce part accuracies approaching 0.001” with a very good surface finish, there are limits to the materials it can reliably process in this high tolerance range. Those limits include types of materials, thickness limitations and material quality. While a high definition plasma cutter would be unaffected by a coating of scale and rust on 1/2" mild steel plate, a laser cutter would struggle and end up scrapping a lot of parts. An abrasive waterjet cutter can produce parts from 2” stainless steel to within 0.003” but its cutting speed for 11 gauge stainless steel would be less than one-fifth the rate of a laser cutter. In another example, a 200 amp high density plasma system can cut 0.5” mild steel at twice the rate of a laser cutter; however, the part accuracy would not be as good as the < 0.003” parts produced by the laser cutter. As with any machine tool purchase, getting the correct CNC cutting system for the job begins with letting the application drive the purchase. |
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Waterjet Cutting |
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The waterjet cutting process uses a low volume, very thin stream of ultra high pressure water for cutting high precision parts. This thin stream of water leaves the cutting head at over twice the speed of sound, and when a small amount of abrasive is added to the stream it is able to cut virtually any material. Waterjet cutters are able to cut soft materials such as rubber gaskets at very fast rates and with a quick change in cutting heads, thicker materials such as 4" stainless steel can also be cut to to part accuracies < 0.004". |
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Laser Cutting |
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The
laser cutting process uses a focused beam of high energy infrared laser
light to cut material by selectively vaporizing and melting a highly
localized area, while an assist gas is used to remove the molten material
from the resulting cut. The
laser cutting process is one of the fastest and most accurate methods
for cutting a variety of metals and non-metals.
Laser cutters can process 16 gauge stainless steel at speeds up
to 400 IPM, while at the same time attaining part accuracies approaching
0.001".
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Plasma Cutting |
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The
plasma cutting process uses a controlled electrical arc to create a
superheated gas plasma jet. This electrically conductive, ionized gas plasma is hot enough to
easily cut through a variety of metals, with part accuracies better than
0.008" attainable with the high density torch designs.
Plasma cutting systems are most often used when the tight
tolerances of a laser cutter (and it's higher capital costs) are not
required. |
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Process Comparison |
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Waterjet Cutting |
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Advantages |
Disadvantages |
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Cuts everything Can produce part accuracies better than 0.002" Doesn't heat part or cause micro fracturing Able to cut
materials over 10" thick Can produce cut edge squareness <
1 degree Minimal kerf widths (0.025" to 0.050") Easily expandable to
multi-head cutting
Fast learning curve for operators Simple maintenance No fumes generated from process
Can be less than half the purchase price of a
similar sized laser
system |
Slow
cutting speeds for most metals as
Can be noisy Area around machine can become coated in
Process generated abrasive dust can damage unprotected motion
components High cost for
cutting media (garnet), can be more than $12 per hour Disposal of "mud" debris and overflow
water from cutting tank can be an EPA issue Focusing nozzle in cutting head deteriorates with
use, affecting cut quality and accuracy |
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Laser
Cutting |
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Advantages |
Disadvantages |
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Cuts a variety of metals and non metals
Can produce part accuracies better than 0.002"
Can cut thinner metals at over 300 IPM
Can produce cut edge squareness < 1 degree
Narrow kerf widths (0.006" to 0.015")
Can cut hole diameters < 1/2 material thickness
Produces narrower heat affected zone than plasma
Can process thin and thick metals simultaneously |
Significantly higher
capital cost Cutting
metals reflective to the laser beam (such as aluminum) can be hazardous
to the focusing lens Can
cause micro fracturing on some materials, a detriment for some aerospace
applications Variations
in material quality for carbon steel plate as well as surface rust can
affect cut results Produces
heat affected zone High cost for
cutting assist gas, can be more than $15 per hour Long
learning curve for process Laser
maintenance requires advanced knowledge Produces
fumes from the cutting process Poor cutting results for most plastics Safety requirements to protect operator from laser beam |
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High
Density Plasma Cutting |
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Advantages |
Disadvantages |
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Cuts
a wide variety of metals Can
produce part accuracies better than 0.008" Can
process 16 gauge mild steel at over 200 IPM and 1" thick mild steel
at over 45 IPM Fairly
quick learning curve for process Simple
maintenance
Can be less than one
third the purchase price of a similar sized laser system |
Not as accurate as laser or waterjet Not
ideal for applications with high volume hole cutting Consumables
in cutting head deteriorate with use, affecting cut quality and accuracy Requires cutting head component change to process different metals and different metal thicknesses Not
as flexible as laser in simultaneous processing of thin and thick metals
Edge quality on plasma cut
stainless steel not as acceptable in some markets as laser or waterjet processed
parts Can
cause micro fracturing on some materials, a detriment for some aerospace
applications Produces
fumes from the cutting process |
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