Tech Briefs Magazine - September 2021 - PIT-19

TECHNOLOGY LEADERS Optics
Optimizing 5G Fiber Optic Filament Production
F
undamental ball screw technology
hasn't changed much since 1929
when Rudolph G. Boehm patented
what he called an " anti-friction "
nut. The ability to move heavy loads
smoothly and precisely is a key process
which continues to enable engineering
innovation today. Nowhere is this more
evident than in the production of fiber
optic filaments, where ball screws are
helping manufacturers meet the growing
demand for fiber optic cables generated
by 5G communications.
Delivering Fiber Optic Strands for 5G
Communications
Wireless carriers are just beginning to
roll out 5G communications, but expectations
with even the most conservative
estimates are projecting at least a 10-fold
speed increase over 4G. This will impact
everything from cell phones and laptops
to driverless cars. The realization of 5G
communications is boosting the
demand for high-bandwidth fiber optic
cable, which requires continuous
improvement in the fiber optic manufacturing
process. This begins with the
creation of highly treated, multilayered
silicon rods called preforms. These provide
the silicon that will eventually be
drawn into filaments approximately the
width of a human hair and joined with
hundreds of similar strands to produce
the fiber optic transmission cables that
will carry the 5G signals.
To start the conversion of the preform
into a single strand, a technician climbs
to the top of a drawing tower and loads
it into a feed mechanism that will lower
it into a high-temperature furnace.
Once the preform arrives at the heating
element, gravity takes over and the
molten silicon drips and narrows to its
intended diameter. As it cools and hardens,
the filament passes through a laser
micrometer to assure 99 percent width
consistency. It is then pulled onto a takeup
spool that will gather as much as
32,808 feet of filament before transfer to
a fabricator for incorporation into the
final cable.
Critical to the success of the process is
the control over the speed with which
the system feeds the preform. Due to
Photonics & Imaging Technology, September 2021
Cov
ToC
Figure 1. Final stages of production, in which silicon filament narrows to its desired width, cools and passes
through a laser micrometer before being pulled onto a take-up spool.
the thin nature of the fiber, slow and
steady movement of the feed unit (one
meter per hour) ensures that the production
is stable. Any faster than that,
and the furnace will be unable to melt
the preform fast enough. Anything slower
will break the continuity of the
stream. Many of the world's leading
fiber optic wire producers accomplish
this with ball screw technology, which
provides high stability and smooth
movement at such low speeds.
Selecting Ball Screws for Fiber Optic
Drawing Towers
In a typical ball screw configuration,
the feed mechanism anchors to the ball
screw nut with a rod. The nut rides down
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Tech Briefs Magazine - September 2021

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