Medical Design Briefs - May 2021 - 18

TECHNOLOGY LEADERS Materials/Coatings/Adhesives

components and complete
the device's protective structural shell.
* Problem: The close-tolerance
plastic cover must be bonded gap-free and watertight,
but the weld process and
cover structure cannot exert undue compressive
force on the sensitive electronics. Reliance on a
single-factor weld mode,
such as distance, could in
some cases result in excessive pressure on the cover
and potential damage to
internal electronics.
* Solution: The combined
material density and reactivity scores in dynamic
mode can optimize distance mode in each weld
cycle, allowing the actuator
to achieve part-collapse
depth sufficient for watertight sealing, yet detect
and avoid levels of resistance that equate with the
compression of electronic
components.

of drilled holes, and molded insert quality (surface
roughness, flash). Use of a
single-factor weld mode
like energy to deliver precisely the same force for
each insert could, as a
result of multiple variances,
result in overinsertion and
substrate or insert damage
or result in underinsertion,
misalignment, or pull-out.
* Solution: By augmenting
energy mode with material density and reactivity
scores, the dynamic mode
feature is able to measure
and moderate the input
of weld energy for each
insert, aiming for a target
condition - a uniform
measure of insert resistance - that equates with
insert pull strength.

Conclusion
For many medical device
and medical product manufacturers, current singlefactor weld modes, together with continued advances
Welding a Sealed,
in equipment precision
and data-gathering capabilElastomer-Core Plug
ity, may well provide adeConsider a sealed, twoThe new dynamic mode in the Branson GSX-E1 2.0 ultrasonic welder from Emerson recalway connecting plug. The culates and adjusts welds in real time to compensate for the varying depth and resist- quate margins of weld,
assembly, and medical
outer shell of the plug con- ance of compressible plastic parts. (Credit: Emerson)
product quality. However,
sists of a molded plastic cup
for manufacturers facing significant or
* Solution: The density score in dynamic
and lid that contain holes through
which metal connecting pins protrude.
unexpected application challenges,
mode can adjust for the varied consisInside, connecting pins are embedded
such as the need to manage multiple
tency of the elastomer by requiring not
in a compressible core of elastomeric
part- or material-related variables, new
only that the actuator travels the
plastic. Because the finished plugs must
assembly technology like dynamic mode
required distance but also that it feels
be air- and water-tight, the weld-on lid is
weld controls may be just what an assemthe required amount of resistance (e.g.,
designed to compress the elastomer
bly process needs. Instead of thinking
contact with the harder material on the
radially around the connecting pins. A
about how to redesign a hard-to-assemplug's rim) before welding commences.
flat " fit " is essential for the lid, as is a
ble part or augment an existing weld
consistent exposed length for the conprocesses with new sensors, ask an
Inserting Structural Pins into a
necting pins.
assembly technology supplier for help.
Substrate
* Problem: The height of the plug's elasThe solution to an assembly problem
Consider the need to insert structural
tomeric core may vary by up to 10
may already be available.
plastic pins into plastic substrates that
percent, so achieving consistent posiThis article was written by Tarick Walton,
vary in hardness, like composites, while
achieving consistency in insertion depth
tioning, shell contact, and weld qualGlobal Product Manager - Ultrasonics for
and pull strength. The structural pins fit
ity for the lid is very difficult. Use of a
Branson Welding and Assembly, and
into grooves essential for assembly of the
single-factor weld mode like distance
Christoph Manger, Product Manager for
larger product.
mode would likely result in variances
Ultrasonics in Europe, Branson Welding and
* Problem: Inserts must deliver consistent
in the height of the lid/plug assemAssembly, Emerson, St. Louis, MO. For more
strength despite variability in material
bly and the exposed length of the
information, visit http://info.hotims.com/
hardness, the depth and diameter
connecting pins.
79413-344.

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Medical Design Briefs, May 2021

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Medical Design Briefs - May 2021

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