Shrink boots provide mechanical and environmental protection to
connector-to-cable transitions. Specially formulated polymers are
injection-molded, then heated and expanded. The shape-memory
property of the material allows it to return to its original shape
when heated with a hot air gun. Optional adhesive coatings on the
inside of the boot provide a watertight, high-strength bond to the
cable jacket and the connector or adapter.
This short presentation covers Glenair Series 77 Full Nelson
Shrink Boot products designed for high-reliability interconnect
cable applications.Heat shrink boots and other molded shapes offer
fast and easy protection of terminations and transitions common
addition to a wide range of cable construction types including
open-loom wire harnesses and backshell-equipped jacketed
cables.
Made of flame-retardant elastomeric resistant to high
temperatures and chemical exposure, boots are produced for both
straight and angled cable entries in a wide range of sizes.
The range of possible boot shapes is almost limitless and can
accommodate both circular and rectangular connectors as well as
multi-branch fittings.Heat shrink boots and other molded shapes can
provide strain relief and backshell or connector sealing.
Boots also organize or route multi-branch assemblies and are
ideal for re-sealing cables and conduit junctions and adapters
subsequent to field repair.
Applications for jacketed cables or conduit assemblies sealed
with boots range from battlefield electronics to under-vehicle
systems on rail cars or trucks.
Where a serious immersion potential exists, particularly for
cables that see rough handling in addition to chemical or water
immersion, a superior performing cable design, such as overmolding,
should be considered.Boots are designed for use with connector
adapters, or backshells, which attach to mil spec type connectors.
Adapters have a boot groove to accept an interlocking lip on the
boot for improved strength and can be unthreaded from the connector
for repair of damaged connector pins.
Lipless boots are designed for direct attachment to connector
threads. The adapter is eliminated, saving weight and space but the
ability to terminate EMI shielding or perform other backshell
functions is lost.
Both types are available with or without adhesive lining which
provides improved sealing and mechanical strength.
Glenair shrink boots are available in three materials:
Type 1, a high performance elastomer provides excellent
resistance to heat, oils and fuels. Type 2 zero halogen material is
intended for applications where low toxicity is a must. Type 3
general purpose flexible polyolefin is a good choice for occasional
exposure to heat and chemicals.This slide presents the standard
part number breakdown for our catalog shrink boot products.
Table I lists the basic part numbers for the various
configurations of lipped and lipless boots.
Our Series 77 Full Nelson Environmental Shrink Boot catalog uses
simple tables to assist in ordering.
Once you have chosen the type of boot required, simply select
the correct size and adhesive type from the table. Adhesives used
in heat shrink boots deserve some added attention. Heat-shrink
boots are not watertight unless equipped with factory-installed or
user-installed adhesives. When heat is applied to the boot, the
adhesive melts and fixes the boot to the adapter and cable jacket
to provide the necessary sealing as well as mechanical
strain-relief. Hot melt thermoplastic polyamide adhesive is
compatible with most cable jackets, economical and easy to install.
Glenair hot melt adhesives of this type are available in two
temperature ranges: W1 for -55 to +105C, and W2 for -40 to +70C.
But for maximum temperature range and best adhesion epoxy-lined
boots are recommended. Glenair Type R one-part epoxy precoat
provides protection from -75 to +150C with high strength.
Glenair adhesives are designed to match-up against Raychem and
Hellerman boot materials and adhesives. The four Glenair adhesives
consist of a high performance two- part epoxy described as U in the
USA and IEC specs, a one-part epoxy described as R in the USA and
IEC specs and two pre-coated hot melts described as W1 and W2 in
the USA and IEC specs. Manufacturer adhesive codes are further
explained in this table.
There are three specifications for adhesives in the heat shrink
world, SAE AS5258, VG95343 part 14, 15 and 18, and IEC 62329-3-101
and -102. All three specifications evaluate peel and shear strength
for harness test assemblies.
All Glenair adhesives and adhesive-lined boots meet or exceed
their controlling specifications in every categorywith ample safety
margins.
While performance values such as dynamic shear, static load,
flexibility and peel adhesion may vary from one boot manufacturer
to the next, all such products must meet the standards of the
controlling specifications to be considered suitable for use in
high-reliability applications. Glenair type "R" adhesive meets all
the requirements of the controlling specifications with significant
safety margins. The material delivers Peel Adhesion test values of
100 N/25mm and Dynamic Shear values of 820 N. The Tyco/Raychem /225
adhesive also tests above the requirement with Peel Adhesion test
values of 140 N/25mm but with Dynamic Shear values of only 540
N.
Glenair's one part pre-coated adhesive ("R") does not match
Raychem /225 for peel adhesion but is better in direct shear, has
better handling properties, and delivers better flex resistance
performance. When installed properly, the material easily meets the
"gorilla test" since a peeling force of 100N/25mm (25 lbs) is
easily more than a normal person can exert with their fingers.
Again, our tests demonstrate the Glenair boot with "R" adhesive
is a superior performing product due to its advanced resistance to
flex damage such as separation and cracking on the cable-end of the
assembly. For compete test results, or a product sample, please
contact the factory.An ordinary heat gun is all that is needed to
produce the chemical reaction that closes a heat-shrink boot to the
cable. Once the boot is positioned and seated properly, heat the
part only to the specified temperature. Adhesive lined parts
require longer heating. Complete installation instructions are
provided in the Series 77 Full Nelson Environmental Shrink Boot
catalog.Product documentation is available at www.glenair.com,
including a complete catalog as well as technical marketing
datasheets on adhesives and a part number cross reference.Thanks
for your time and attention.
