High-temperature polymers are printed
using high-end extrusion technologies and
powder bed fusion technologies, known by
the branded name Selective Laser Sintering
(SLS). SLS’s unique combination of heated
build chambers and focused laser beams allow for materials with higher melting points.
The most common printed material in
powder bed systems is nylon. While Nylon
11 has been commercialized to some
extent, Nylon 12 is the most popular laser
sintered material, and it is sometimes used
to create surgical guides. With respect to
implants, Polyetherketoneketone (PEKK)
parts are most common, although they
are utilized for lower-impact implant
applications like spinal and maxillofacial.
For higher stress applications, such as hip
and knee appliances, metals are frequently
used to insure the implants can endure the
frequent impacts and other dynamic loads
they will be exposed to.
Not every high-temperature plastic is
printed with ease.
Nylon 6 and Nylon 6, 6 are under
development and used mostly in academic
settings. Polyether ether ketone (PEEK),
another material being tested in a variety
of academic settings, is also on the horizon.
The challenge of maintaining tight temperature windows across the totality of a build
for existing machines has limited PEEK’s
commerciality to date.
Resins are also used in the medical field, but
the applications are primarily for instrumentation and surgical guides. Material-jet-ting technologies, which behave much
like traditional inkjet printers, can deposit
multiple materials within a single print. This
can be especially useful for applications like
authentic reproductions of internal organs.
In such situations, digital imaging and com-
munications in medicine (DICOM) data can
been affordably printed on a wide variety
of machines, not just extrusion printers but
also laser sintering printers, for a number of
applications like biodegradable stents.
Other popular low-melting temperature
polymers include Polycaprolactone (PCL),
a biodegradable polyester, which is used
for things like skin grafts due to its ability to
facilitate cell growth, and Polycylcolide (or
polyglycolic acid) (PGA).
There is still a good deal of research to
be done with respect to low- temperature
polymers. However, as Roger Narayan,
Special ASME Fellow to America Makes
notes, what has not yet been offered by
manufacturers to this point is biodegradable
polymers with several different molecular
weights. For example, the ability to print
materials with customized molecular
weights that will facilitate more controlled
degradation of printed devices is an area of
relative immaturity and significant potential
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