Heat shrink tubing or heat shrink is an inherent part of any electric wiring system. It is a plastic tube which shrinks in a specified ratio and provides assistance in the sphere of electrical engineering in several ways. These come in different varieties and types with the composition of each being determined by the desired application. The available varieties range from the microscopically-thin walled ones to the heavy-walled stiff tubing thus fulfilling differing requirements of environmental stress.
Materials Used in Making of Heat Shrink Tubes
The heat shrink tubes are made from several materials depending upon the application for which it will be used. Following list gives an idea of what materials go into its making:
PTFE: The most advantageous material, PTFE or fluorpolymer tubes provide high resistance to punctures and chemicals, offers a broad range of operating temperatures (-55 to 175 degree C) and is equipped with a low friction coefficient.
Viton: This too is another variant of fluropolymer material which provides high chemical resistance, offers broad range of operating temperatures and is very flexible. It is used in hydraulic equipment to a large extent.
Fluorinated ethylene propylene (FEP): It is said to be a low-cost substitute to PTFE. It is highly chemical resistant and has the same qualities as the above two materials. It is a versatile electrical insulator and hence finds best use in applications involving heat shrink tubing.
Elastomeric tubes: High flexibilities are maintained at low temperatures and the range of operating temperatures is -75 to 150 degree C. The material is resistant to several chemicals with petrol and diesel being included and can withstand abrasion in highly extreme environment conditions. The material adheres to strict international specifications.
Polyolefin tubes: This material finds its way into heat shrink tubes which are commonly used by aerospace, military and the railway sector. They are available in a wide variety of colors which is of great help in those applications which require color coding. Black color among the whole lot is recommended for all applications which are meant for outdoors. The commonly available shrink ratio is 2:1 but in some cases a 3:1 ratio can also be got with this material.
In addition to the above, PVC tubes or silicone rubber tubes or woven fabric also offer equal advantages.
How is it used?
The tube is used in its original form before any connection is made to the wire. The original tube is put on to the wire and slid down to cover the area of the joint. If it slides down with difficulty a silicone lubricant can be used to make the task easier. The tube is then shrunk to the specified size such that it fits snugly around the joint. Several methods like use of a hot air gun or heating in oven or any other source providing a hot gas flow can be used. However, care has to be taken to provide heat in controlled measure as otherwise it can lead to uneven shrinkage or melting of the tubing.
Besides the heat shrink tubing, the heat shrink tape and heat shrink boot are also required in equal measure while working in any electrical or electronic setting.