1. Heat Shrink Tubing
Heat shrink tubing is a mechanically expanded extruded plastic tube that shrinks to between one
fifth and one sixth its original size when heat is applied. The most common materials for heat
shrink tubing are nylon and polyolefin. Manufacturers produce heat shrink tubing in a wide array
of varieties. The exact chemical composition is determined by the intended purpose. Heat shrink
tubing can be microscopically thin or thick, heavy and rigid. Manufacturers grade the quality of
heat shrink tubing by the expansion ratio, which compares the expansion rate to the recovery rate
of the tubing. Heat shrink tubing is used to insulate the wires of electrical systems. Heat shrink is
also used to protect wire, conductors, connections, joints and terminals. If the insulation
surrounding wires has been damaged, heat shrink tubing can be applied to protect the exposed
wires.
Raw heat shrink tubing, meaning tubing to which has not been applied, is first fitted to the wiring.
After the tubing is snugly in place, an over or heat gun is used to raise the temperature of the
shrink tubing. It is possible to apply heat to apply heat to the tube with a soldering iron or even
the heat from an ordinary lighter; however, when using these methods there is less control of the
heat, which can lead to an uneven finish, and can even damage the shrink tube. Manufacturers of
heat shrink tubing typically caution against using a lighter or soldering iron to apply heat to the
tubes because it can damage the tubing or lead to its malfunction. When the heat is applied to the
heat shrink tubing, the diameter of the material will reduce by 15% - 50%, depending on the type
of material used.
The Raychem Corporation, which was located in Menlo Park, California from 1957 until it was
acquired by Tyco International in 1999. In 2007, Tyco International split, Covidien and Tyco
Electronics. Tyco Electronics still sells shrink tubing under the Raychem brand.
Manufacturers of heat shrink tubing out of thermoplastic materials. Common thermoplastic
materials include polyolefin, fluoropolymer, Polyvinyl chloride, neoprene, silicone elastomer and
Viton. The material used determines how the heat shrink tubing will react when heat is applied. If
the manufacturer wants the heat material that was shrunk to become denser when heat is applied,
material containing monomers, or molecules that bind chemically to other molecules for a
polymer. When the monomers chemically bond, they take up less space. As the volume of the
material decreases, its density increases.
Materials used to manufacture heat shrink tubing vary by their operating temperature range.
Fluoropolymer operates from -55 to 175 °C. Viton operates from -55 to 220 °C. Elastomeric
tubes use a range of -75 to 150°C. Polyolefin has a range of of -55 to 135 °C.
An additional function of heat shrink tubing is the color coding of wires. In the 2000s, computer
manufacturers began heat shrinking the interior wiring of computers in order to create a tidy
appearance.