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By Jim Reitz, General Manager, Union Tech
Challenge of 3D Manufacturing
Characteristics of stereolithography, along with material improvements, help advance 3D printing.
The landscape of additive manufacturing has changed ramatically since the commercialization of
stereolithography (SL) as the first viable 3D-printing
technology. In fact, the terms “3D-printing” and
“additive manufacturing” (AM) only entered the popular
vernacular in recent years.
The scope of additive manufacturing has changed
dramatically. Technologies encompassing thermoset
and thermoplastic materials, along with metal, have
proliferated. The 2017 Wohlers Report lists 96 different
additive manufacturing equipment suppliers across
a broad range of technologies. Substantial advances
in equipment, software, and material are occurring
concurrently with increasing computer power and
growth in the 3D CAD-installed base. Competition
within the early technology supply base has increased
as patents expire and new players come to the
Today, the inherent characteristics of 355-nm laser-
based stereolithography technology characteristics
leverage ever-expanding material capabilities to
mature into one of the widest-used and highest
utility AM processes. The term SLA, a registered
trademark of 3D Systems, is often used by some to
encompass various 3D-printing processes that fall
within the ASTM grouping of AM processes as “Vat
Stereolithography in this discussion will be focused
on “industrial SL,” as the original technology has
evolved and is differentiated from all other vat
polymerization processes by:
• Platform sizes ranging from 250 mm ( 9. 5 in.)
square to over 800 mm (31.5 in.) square.
• Ultraviolet laser (355-nanometer wavelength)
• Materials formulated for 355-nm UV including
clear, pigmented, and composite systems.
• Imaging from above (build platform travels
The use of a laser to instantly cure photopolymers
using a UV laser with a nominal spot size less than
0.2 mm provides one of the highest combinations of
accuracy and resolution of any AM process, especially
considering the range of part sizes the procedure can
handle. Today’s 355-nm SL materials can produce
parts that have excellent dimensional consistency and
surface aesthetics ranging from transparent to various
colors resembling typical injection molded parts.
These materials have overcome robustness and aging