STEREOLITHOGRAPHY
"SLA"
(overview)
Stereolithography is the most widely used rapid
prototyping technology. Stereolithography builds
plastic parts or objects a layer at a time by
tracing a laser beam on the surface of a vat
of liquid photopolymer. This class of materials,
originally developed for the printing and packaging
industries, quickly solidifies wherever the
laser beam strikes the surface of the liquid.
Once one layer is completely traced, it's lowered
a small distance into the vat and a second layer
is traced right on top of the first. The self-adhesive
property of the material causes the layers to
bond to one another and eventually form a complete,
three-dimensional object after many such layers
are formed.
Some objects have overhangs or undercuts which
must be supported during the fabrication process
by support structures. These are either manually
or automatically designed and fabricated right
along with the object. Upon completion of the
fabrication process, the object is elevated
from the vat and the supports are cut off.
Stereolithography generally is considered to
provide the greatest accuracy and best surface
finish of any rapid prototyping technology.
Over the years, a wide range of materials with
properties mimicking those of several engineering
thermoplastics have been developed. Limited
selectively color changing materials for biomedical
and other applications are available, and ceramic
materials are currently being developed. The
technology is also notable for the large object
sizes that are possible.
Stereolithography SchematicOn the negative
side, working with liquid materials can be messy
and parts often require a post-curing operation
in a separate oven-like apparatus for complete
cure and stability.
Recently, inkjet technology has been extended
to operation with photopolymers resulting in
systems that have both fast operation and good
accuracy. See the section on inkjets.
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The term | Simple
