K-HSTTA Panduit Corp, K-HSTTA Datasheet - Page 28

• Manufacturer Part Number: K-HSTTA
• Description: KIT HT SHRINK ADH 3/16"-1" BLK
• Manufacturer: Panduit Corp

28
PANDUIT
Extrusion
Heat Shrink Process Defined
Various thermoplastic materials that will repeatedly melt and flow, such as polyolefin, PVC, etc., are extruded
into tube form. If examined at a molecular level, the material would resemble long thin strands weakly
connected at various points by crystalline structure. If left in this state, the performance of the tube would be
limited to that of the base material.
Cross-linking creates high strength bonds between the molecular strands, in addition to the crystalline bonds.
This is done with a high voltage or chemical treatment of the material. The cross-link bonds will not break
down with heat; this transforms the material from a thermoplastic to a thermoset material that will not melt
and flow. The result is a material with superior electrical and mechanical proper ties.
The cross-linked tube is heated and the crystalline bonds dissolve, however, the cross-link bonds remain.
The tube now is softer and can be expanded. This causes the cross-link bonds to stretch. When cooled
quickly, the crystalline bonds reform, freezing the tube in the expanded size. The tubing has now completed
the manufacturing process.
With the proper type and size of tube selected, the tube is placed over the object to be covered. Heat is now
applied. This causes the crystalline bonds to dissolve again and the tube softens. The stretched cross-link
bonds now return to their original length and the tube shrinks to the diameter it had when cross-linked, unless
it encounters an object larger than this diameter. In this case, it conforms tightly to this object.
Heat Shrink Installation Instructions
Position heat shrink over the object to be covered. Using a heat gun, soft yellow flame torch, infrared heat
source or oven, evenly heat the tubing until it has fully recovered and conforms to the object. Use caution not
to char or burn the tubing. See
TFE tubing is the most difficult to shrink due to its high shrink temperature. TFE shrink tubing must be heated
to the gel state 621° F (327° C) to completely recover. This can be recognized when the tubing changes from
milky white to clear color. It can be shrunk with a heat gun or torch, however, it is very difficult to use these
methods since they have a tendency to overheat the tube in one area while other areas remain too cool. The
most reliable way to shrink TFE is in an oven. Position the heat shrink over the object to be covered and place
it in an oven set at 800° F (427° C) until the tubing turns clear. Once clear, remove assembly from oven to
prevent over heating and allow it to cool at room temperature. Do not quench in cold air or water. Large
objects, particularly metal tubing or rods, must be preheated to get a uniform shrink. FEP material, PANDUIT
HSTTF, is easier to shrink and use of a heat gun, torch or oven will yield good results when the tube is heated
to 350° F (177° C).
®
D
RY
-S
HRINK
™
Special Instructions for HSTTT and HSTTT4X
page 24
, D
Cross-Link
AMP
for the shrink temperature of each type of Panduit tubing.
-S
Technical Data
HRINK
General Instructions
Extrusion/Material
Cross Linking
Expansion
Recovery
™
and W
ET
-S
HRINK
Expansion
™
Heat Shrink Tubing