Advanced Polymers Polyester Heat Shrink Tubing and
Beahm Designs
Split Die Thermal Bonder; an unbeatable combination for Thermal Balloon Bonding.
Background:
Advanced Polymers, Inc. was looking for a reliable fast simple method of bonding
its line of polyurethane balloons.The Split Die Thermal Bonder provided an affordable
alternative to laser welding, RF die bonding, and adhesive bonding. This unit applies
uniform heat to a variety of thermal bonding and modification processes. The cycle
begins when hinged dies are heated to a constant temperature controlled by thermocouple
feedback. Tubing to be welded or modified, are assembled over a PTFE mandrel, and
a Polyester Heat Shrink Tubing, manufactured exclusively by Advanced Polymers, Inc.,
Salem, NH USA, is positioned over the bond area. The die halves are closed and encompass
the shrink tubing to apply uniform heat to the component for the duration specified.
USER BENEFITS: Provides you with fast, highly repeatable bonds especially when used
with Polyester Heat Shrink Tubing. -Allows you to perform highly precise bonds for
demanding applications such as short balloon bonds and ultra smooth lap & butt
welds. -Adjustable clamp pressure varies compression force on joint. -Compact design
provides you with greater work space. SYSTEM SPECIFICATIONS: Temp range: ambient
to 525 deg. F., Bond widths: As short as.062 and as long as 1/2" (Custom dies
on request). Bond Diameters: Up to 1/2" standard, (Larger on request). Ambient
cooling air.
The Bottom Line: By putting the heat on to the balloon bonds by
direct contact with the thin wall heat shrink and using the cooling air to protect
the balloon we were able use our Polyester Heat Shrink Tubing to provide a constant
compression force uniformly around the melted balloon neck and shaft materials.
This compression force made the materials flow together into a single polymer structure
as well as provide a smooth, glass-like tapered finish to the bond area.
The Key properties of Advanced Polymers Polyester Heat Shrink Tubing in this
application
- Ultra thin wall results in rapid shrinkage and heat transfer to the parts to be
fused.
- Low shrink temperature and rapid shrinkage allows initial application without part
distortion
- High melt temperature allows use of a high enough temperature to cause the substrate
to melt and flow
- Ultra smooth “glass like” surface finish after forming
- Easily removed
- Does not stick to most materials
- Clear material enables visual monitoring of the process (if required)
List Key Technologies: Our cost in development was essentially
the cost of the machine, the cost of a few feet of shrink tubing (~$125.00 for a
25' trail kit), the cost of a couple of dozen balloons (~$600), the extrusions they
were bonded to (~$25) and one day of engineering time.
How it Happened: We had been faced with bonding very thin walled,
highly elastic urethane balloon necks to a catheter shaft. Adhesives worked only
at very low pressures. Although we got adhesion, the necks of the balloon would
stretch as the balloon grew under pressure and the peel force was just too great
for the adhesive to hold the balloon neck in place. We had done thermal bonding
in the past using hot air and our heat shrink tube. The resultant bonds were glass smooth
and were incredibly strong. The problem was that the hot air was not easily directed
and controlled. The results were that some times the balloon, which is sensitive
to heat, would get distorted. It took a great deal of skill and luck to have each
part come out acceptable each time. Once we got the
Beahm Designs
Split Die Thermal Bonder and made the first jaw modifications to accommodate the
balloon necks, it was a matter of one day’s worth of engineering work to establish
parameters and evaluate the results. In just two or three attempts we had our first
bonds. They were evaluated by dissection of the bond areas and burst testing the
balloons and found to be as good as our best efforts using other processes.
Conclusion:
We are very pleased with the Thermal Die Bonder and very excited about using our
Polyester Heat Shrink Tube with it. The ulta thin walls of the Polyester Shrink Tubing
results in rapid shrinkage and heat transfer to the parts to be fused Because the
heat shrink tube provides a uniform compression force in the radial direction and by
virtue of its longitudinal shrinkage, also provides linear compression of adjacent
tubes, we are not only able to make balloon bonds with this equipment, but have
been able to make butt joints in single lumen tubes. This machine is very useful
in attaching soft tip materials to catheter shafts and in the same operation tapers
the ends of the tube. Again the Polyester Heat Shrink Tube imparts an ultra smooth “glass
like” finish and can easily taper the tube to a knife-edge without the cost
of high priced equipment and tooling. The combination of this thermal die bonder
and the use of
Polyester Heat Shrink Tubing
available exclusively from Advanced Polymers, Inc (Salem, NH, advpoly.com)
are unbeatable in terms of cost effectiveness, easy of use and quality.