Medical Design Briefs: 2021 Technology Leaders - 8

TECHNOLOGY LEADERS Electrical Connectors/Wires/Cables
Nitinol stents are becoming more and more widely
used in surgeries. (Credit: Ulbrich)
Mechanical Properties - Tensile
What starts as ultra-fine wire ends up as braid products such as stents. (Credit: Ulbrich)
PAD. This is due to the force the nickeltitanium
alloy can provide when it
comes to holding open vessels, while
still having enough elasticity to breathe.
The two applications above are the primary
use of nitinol round wire, but
other applications include:
* Heat engines.
* Resilient glass frames.
* Orthodontic arc wire.
* Medical devices.
* Actuators.
Nitinol is generally produced in large cast ingots and
can be subsequently processed all the way down to
ultra-fine wires. (Credit: Ulbrich)
where accuracy is of utmost importance,
such as cardiovascular or neural
surgeries. The advantage of this is the
superelasticity of nitinol. It will act
almost like a spring in that it can be
stretched significantly and then return
to its original shape. This is extremely
beneficial in the medical field as the
use often involves bending and twisting
through arteries.
Another application for nitinol wire
in the medical industry is braided
stents. Nitinol stents are becoming
more and more widely used in surgeries,
especially to treat stenosis issues
and issues below the knee. Nitinol
stents would more so be used for the
latter and is often a suitable choice for
peripheral vascular disease, known as
8
* High-reliability couplings.
* Temperature control system couplings.
Characteristics Affecting Nitinol
Performance
There are multiple characteristics when
it comes to producing and manufacturing
this wire that will affect the final application:
Physical characteristics, including
size and tolerance, and me chanical properties,
including tensile strength, elongation,
and surface condition.
Physical Characteristics - Size and
Tolerance. Size: nitinol is very abrasive on
wire drawing dies and has to go through
these dies multiple times to achieve the
small diameters required in the medical
industry. Tolerances: Tight tolerances
need to be held when it comes to the
diameter but just as important, they need
to be consistent throughout the entire
length of the wire. This is beneficial not
only to the end use, but to minimize wear
and tear on the drawing die.
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Strength, Elongation, and Condition.
The typical two conditions for nitinol
ultra-fine wire are cold worked and
straight annealed. The preference de -
pends on the processes of the medical
device OEM and their manufacturing
operations. Most of the wires will be heat
set into superelastic condition at the
next manufacturing tier.
Controlling all of these characteristics
throughout the wire and ensuring uniform
dimensions is essential to producing
a good product and saving money in
production. Precision equipment is re -
quired to keep these properties in check
because even small inconsistencies re -
sult in issues, such as unusable parts or
excess scrap, at the next manufacturing
step in coil reinforcement.
Final Considerations of Ultra-Fine
Nitinol Wire
Since nitinol also has a unique ability to
adapt to extraordinary strains and is compatible
with the human body, it is finding
numerous applications in the medical
field. What starts as ultra-fine wire ends up
being used for braid products such as
stents, orthodontic wire, catheters, and
other surgical implant devices. With end
uses like these, it is essential for medical
device manufacturers to select an alloy
and a supplier that provides materials
with undeviating, consistent mechanical
properties, ensuring that those properties
are appropriate for processing medical
wire. Both production methods and manufacturing
sources are equally important
in supply chains within the high-tech
medical device industry.
This article was written by Doug Horan,
Business Development/Marketing Specialist
for Ulbrich Stainless Steels & Special Metals,
North Haven, CT. For more information,
visit http://info.hotims.com/79409-344.
Medical Design Briefs 2021 Technology Leaders

http://info.hotims.com/79409-344 https://www.medicaldesignbriefs.com

Medical Design Briefs: 2021 Technology Leaders

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