Waterjet machines use cold supersonic abrasive erosion to
cut almost any material, both metals and nonmetals.
The highly pressurized
water stream carries abrasive garnet to etch away the material.
Wire electrical discharge machining (EDM) uses spark erosion
to remove material from electrically conductive
materials. The wire is negative
and the work piece is positive. Direct-current electric pulses are generated
between
the wire electrode and the work piece. During cutting, material is
melted away by the lightning bolt and flushed
out of the kerf area by the
dielectric solution.
|
Comparison matrix of different cuting process such as waterjet,
wire EDM, laser, plasma, milling, and punch.
|
|
|
Waterjet
|
Wire EDM
|
Plasma
|
Laser
|
Milling
|
Punch
|
|
Accuracy
|
Waterjet cutting accuracy average of ±0.003"
(±0.1 mm)
Better result can be
achieve with more advanced software.
|
Wire EDM is Extremely precise parts at
±0.0001" (±0.025mm)
|
Plasma cutting accuracy is in the range of ±0.030 to
±0.060"
|
Accuracy to ±0.001"
(±0.025 mm) or better in thin material.
|
Very good, in the range of
±0.0003"
(±0.01mm)
|
Fair
|
|
Thickness
|
Waterjet Machines mostly cut under 3" (75mm) Thicker parts can
be cut with reduced accuracy and slower speed.
|
Very thick parts can be
cut with wire EDM. Over 12" (30 cm) reported.
|
Plasma cutting usually cuts less than
1.25"
|
Usually cuts thin mild
steel less than 0.25"(6.35mm)
|
Able to work on 3D parts.
|
Usually work well with
thin sheets.
|
|
Cutting speed
|
Waterjet machine cuts five to ten times faster
than EDM when thickness is under 1"
|
Wire EDM cuts at very Slow speed compare to
waterjet (5-10 times slower)
|
Fast with thin sheets
|
Very fast cutting in thin,
non-reflective materials.
|
Fair
|
Fast batch production when
initial programming is done
|
|
Quality of edge
|
Waterjet cutter yields Good edge quality
|
Excellent
|
Fair
|
Excellent
|
Excellent
|
Fair
|
|
Heat affected zone (HAZ)
|
Waterjet produces No HAZ
|
Some HAZ
|
Some HAZ
|
Cuts by melting the
material, resulting HAZ, often need additional process to avoid micro
cracking.
|
No HAZ
|
No HAZ
|
|
Material Distortion
|
Waterjet machine generates No Distortion but may have
hazing near the cut. No internal stress built up.
|
Wire EDM Cuts by melting, resulting
material heat distortion.
|
Cuts by melting, resulting
material heat distortion.
|
Cuts by melting, resulting
material heat distortion.
|
No distortion
|
Some distortion
|
|
Other characteristics
|
Waterjet cutter works well in
non-conductive and conductive materials.
Can pierce material
directly without other drill equipment.
Fast setup and rapid
programming.
Minimal requirement of
fixture.
|
EDM is limited to cutting
only conductive materials.
|
Relatively low capital
costs. Special gas need for laser cutting.
|
Limited to non-reflective materials.
May need different gas for
cutting different materials.
|
Needs special fixture and
tools, also requires skilled operator and usually can not work on very large
parts.
|
Relatively low capital
costs. May need other special tools.
Not work well on on brittle or hardened materials.
|
|
Why buy waterjet machines
|
Waterjet cutters competes
with other cutting methods with good accuracy, fast setup time and cutting
speed, and yields no HAZ.
|
Wire EDM shops buy waterjet machines for fast
speed and to get into non-conductive materials business.
|
Plasma shop owners buy precision water jet
cutters to cut non-conductive material or cut precision parts.
|
Waterjet machines typically cost 1/3 of a
laser and can work on a much wider variety of materials, particularly aluminum
and stainless steel over 1⁄4 to 1⁄2" (6 mm to 13 mm).
|
Traditional metal work
shop owners acquire waterjet cutters to do metal working such as cutting
large work piece with fast turn around and at setup low cost.
|
Punch press owners would
buy waterjet cutters to improve turn around time in doing short runs and
prototype parts. Also to get into cutting thinker materials.
|
