issue: May 2003 APPLIANCE Magazine
Engineering Medical Devices
Taking Tooling to the Edge
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By tooling what some deemed impossible, patients are now able to recover more quickly after having an arterial puncture.
It can be stressful to undergo a diagnostic angioplasty or
other procedure in which the femoral artery is punctured.
Once the procedure is complete, patients often want to be
up and moving as soon as possible, but the most commonly used
methods to stop bleeding can be slow and uncomfortable. Traditional
techniques include manual or mechanical pressure, such as
a clamping device, and 4-8 hr of lying flat without moving
the affected leg. St. Jude Medical, Incorporated developed
the Angio-Seal™ vascular closure device to seal arterial
punctures created during these procedures, helping patients
hit the road to recovery faster and more comfortably.
top of the letter "A" on the locking tensioner
cap was trapping gas, and resin couldn't flow into that
area. This problem was solved by thinning out the area
around the top of the letter and adding some venting,
which allowed trapped gas to escape.
uses a very small anchor, collagen sponge, and suture to stop
the bleeding almost immediately. An added advantage is that
the human body absorbs all device components within 90 days.
Although St. Jude has been using this technology for 5 years,
design enhancements - made with the assistance of Phillips
Plastics Corporation - have made the current Angio-Seal
device easier to use and more reliable. Phillips and St. Jude
worked together to make improvements for ease of use and to
incorporate multi-shot soft-touch features. In the process,
the injection molder designed and built a multi-shot tool
to address specific Angio-Seal requirements.
Angio-Seal components have proven challenging due to their
part designs, which require complex multi-shot molds. St.
Jude chose multi-shot technology to give the updated Angio-Seal
better aesthetic appeal and contrasting graphics. Although
St. Jude has in-house injection molding capabilities, it selected
Phillips because of its responsiveness, expertise in designing
cutting-edge tooling, and a history of successful multi-shot
very difficult parts - multi-functional and tight toleranced,"
says St. Jude Medical's Design Engineer Jack White.
"We have our own tool shop here, but we were overloaded
and unable to build tools. We also don't have multi-shot
capability at this time."
the former Angio-Seal assembly was not as intuitive as the
company desired. The new design, which simplifies how the
Angio-Seal is used, incorporates a host of complicated features,
resulting in a far more complex set of components than the
previous design. To better understand the program's
requirements, Phillips' project team met with St. Jude
to learn how the Angio-Seal works and to determine critical
During this initial
discovery phase, Phillips garnered support from disciplines
as far reaching as design, prototyping, processing, and post-molding
operations to provide the services St. Jude required. Based
on information gathered, stereolithography (SL) and selective
laser sintering (SLS) were employed to verify that proposed
revisions remained within the parameters of the Angio-Seal's
U.S. FDA-approved design. To change the functional aspects
of the design would result in added cost and time to retest
the components for regulatory approval.
Jude's Angio-Seal allows physicians to stop the bleeding
instantly during diagnostic angioplasty and other procedures.
of the greatest program challenges came with the locking tensioner
cap, which snaps into its mating part with precision slots.
To form the slots, a collapsible core was required, which
at the time was deemed impossible by some injection molders.
Phillips' tool designers devised a concept using pins
and slides in a deceptively simple seesaw-type action.
this new tooling concept, a design that was considered nearly
impossible is producing parts today. If the parts couldn't
be molded in this fashion, the solution would have been to
mold two parts and either glue or sonic weld them together.
Because of the difficulty of the desired design, St. Jude
was initially dubious of the success of the proposed tool
In addition to
the complexity of the tool design, there were traditional,
yet complicated features with which to contend. One was
with the graphics. The top of the letter "A" on
the locking tensioner cap was trapping gas, and resin couldn't
flow into that area.
are certain ways that the elastomer likes to fill, and
we gave Phillips a carte blanche on how to achieve that," Mr.
White says. "As long as the logo looked right and
the part functioned the way we designed it, it was really
a case of fit, form, and function. Phillips had to build
the tool. We had the easy part."
This slight bump in the road was quickly resolved. Because the last place to
fill is a thick section, the area was thinned out around the top of the letter.
Some added venting allows trapped gases to escape.
are molding issues that cannot be avoided, but with early
involvement, they are overcome with proactive solutions.
For example, the Angio-Seal locking tensioner cap requires
a valve gate that leaves a small mark on a visual surface.
This was addressed by adding design elements to camouflage
the gating mark. The dimples on the end of the part were
designed to mask a valve gate. Without the dimples, there
would only be the gate mark. Instead, a series of depressions
were made and the valve gate was hidden in one of them.
components are molded in Phillips
Plastics Corporations' class 100,000 clean room.
Equally important to St. Jude is Phillips' ability
to provide validation assistance. "Phillips validated
the process because the parts are shot in-house," says
Mr. White. "We supplied the data we needed, and Phillips
set up the validation parameters."
images were created to determine fill-time for
the Angio-Seal device.
here for a larger image.)