Information

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ELECTRICAL SOLUTIONS
C3.41
B2.
Cable
Accessories
C1.
Wiring
Duct
C3.
Abrasion
Protection
C4.
Cable
Management
D1.
Terminals
D2.
Power
Connectors
E1.
Labeling
Systems
E2.
Labels
E3.
Pre-Printed
& Write-On
Markers
F.
Index
B3.
Stainless
Steel Ties
C2.
Surface
Raceway
E5.
Lockout/
Tagout
& Safety
Solutions
B1.
Cable Ties
A.
System
Overview
D3.
Grounding
Connectors
E4.
Permanent
Identification
Heat Shrink Process Defined
Extrusion/Material
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
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 properties.
Expansion
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.
Recovery
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.
Extrusion Cross-Link Expansion