Medical Design Briefs - July 2023 - 9

fore requiring specific bend radii and
flexibility. Laser cutting provides various
cut geometries assisting with flexibility,
torque and compression. Advanced laser
cutting profiles can be used for steerable,
high-load catheter applications.
Passivation. Hypotube manufacturing
employs a range of processing techniques
to add or remove features from the metal
tube. These processes can introduce contaminants
(free iron) on surfaces, and it
is essential that all contaminants are removed
from the hypotube. Freudenberg
Medical, for example, passivates all of its
stainless steel hypotubes to the international
passivation standard ASTM A 967.
Passivation and electropolishing chemically
dissolve contaminants on the stainless
steel surface, forming a thin protective
chromium oxide layer on the steel,
which gives it's a stainless quality.
Laser Ablation. Marker bands on a coated
hypotube surface help a physician estimate
the longitudinal placement of the
catheter relative to key anatomical structures
as it is introduced into the vasculature.
Automated laser systems remove
PTFE coating from the outer diameter of
the hypotube to create these markers at
various intervals along the shaft.
Centerless Grinding. Centerless grinding
is a machining process that uses abrasive
cutting to remove material from a
metal shaft. A highly accurate outer diameter,
thinner walls, or intricate features on
the hypotube outer profile can be
achieved through this grinding process.
Laser Welding. State-of-the-art laser
welding systems can produce spot-welded
and seam-welded joints in producing corewire
and other micro-welded assemblies.
This welding capability enables engineers
to manufacture a hypotube shaft with advanced
form, shape, or profile features for
the addition of transition elements such as
distal core wires.
PTFE Coating. PTFE coating is a popular
finish on a hypotube's outer diameter,
providing high lubricity to improve
device trackability. Cambus Coat™, a
PFOA-free coating, for example, offers
the highest levels of adhesion over traditional
methods.
Pad Printing. An alternative method
to create the femoral, brachial, and radial
marker bands discussed above is
through the application of a contrastingcolored
ring around the outer coated
surface of the hypotube using a process
called pad printing. The PTFE hypotube
Medical Design Briefs, July 2023
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9
surface is typically black in color and the
pad-printed marker band is typically
white to optimize contrast and visibility
in the cath lab.
Inspection. Product quality and consistency
are paramount in medical device
manufacturing. Material testing
and inspection must be an integral part
of manufacturing processes and should
always follow documented procedures
and systems that comply with customer's
requirements.
This article was written by Steven
Langan, Vice President/General Manager,
Freudenberg Medical, Spiddal, Galway, Ireland.
Contact: infogalway@freudenberg
medical.com. For more information, visit
www.freudenbergmedical.com.
http://www.freudenbergmedical.com http://info.hotims.com/84481-726 http://www.medicaldesignbriefs.com
Medical Design Briefs - July 2023

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