Certain materials that can be cut using waterjet technology receive the benefit of quicker, versatile cuts. This type of
cutting is expanding outside the automotive sector. Another benefit of waterjet is the small amount of waste that comes from
cutting.
- Among the forms of robotic cutting systems;
plasma, laser, trim die and electric discharge media, waterjet
cutting is considered a fast and flexible method for cutting
most plastics, foams and some metals.
- Waterjet cutting uses a stream of water
pressurized to 45,000 to 60,000 pounds per square inch. Some
configurations include an abrasive mixed in the stream. This
abrasive ranges in size from 0.2 to 0.5 mm, depending on the
material being cut. The primary advantages of robotic water jet
systems are speed and flexibility.
- The trim die was the system by which mass
produced cutouts were made in the automobile industry for years.
With the advent of reliable water jet cutting systems in the
early 1990's, trim dies became somewhat obsolete. Trim dies are
large punches that cut out fabrics and carpeting for automobiles.
With water jet, a few keystrokes are all that are needed to reuse
the same robotic cell for different types of vehicles and for
new models.
- One of the disadvantages of water jet is
that despite its speed, a die can stamp-cut a part faster. However,
a die cannot be reconfigured as easily or as quickly. Waterjet
also eliminates the need to replace knives when they get dull.
- The other advantage is that there is no
compression or fraying of the edges as with a press. In piercing
operations, there is not a need for backing under the material
with waterjet. Likewise, stamps and dies get dull after significant
use.
- ''As sheet metal stamping equipment wears
over time, the car companies have to maintain them,'' Russo adds.
- This is time consuming and costly to automobile
manufacturers. By the same token, waterjet leaves no dust in
the wake of its process.
- Some problems associated with heat-generating
cutting methods such as laser or plasma are avoided with waterjet.
- The smoke generated by plasma or laser
cutting can be a health hazard. It is recommended that some materials
not be laser cut at all, or with any other heat-related process.
- Another potential problem with cutting
systems that create significant heat is the ill effects of a
heat-affected zone.
- If the material you are cutting, like plastics,
cannot have a heat-affected zone, then water jet is the method
of choice. A process that generates heat which turns your product
into a molten puddle of slag would obviously not be a good choice.''
- Robots that are especially useful for water
jet are Motoman's SK16MX and UP20M robots as well as Fanuc's
M16i and S500.
- Some automakers specify that parts are
to be cut with a water jet because they realize the advantages
of the flexibility of engineering changes.
