Heat Shrinkable Sleeves for Wires
Heat shrinkable sleeves are used in a wide variety of electrical appliances to bind cables together, and protect components, joints, and terminals. They are used to provide insulation, and to protect the wires from abrasion, water, and chemicals.
Heat shrinkable sleeves are also used to produce heat shrink end caps, which can be used to insulate and protect the cut end of a wire or cable.
Heat shrinkable sleeves are purchased in a size bigger than the diameter of the wire or component that is to be protected. The un-shrunk sleeve is quite thin. When the sleeve is heated, it shrinks down to as much as one sixth of its original diameter, and the walls of the sleeve become much thicker and more durable.
The shrink ratio differs from sleeve to sleeve. The amount of shrinkage that occurs when the sleeve is heated is called the shrink ratio. Common shrink ratios range from 2:1 to 6:1.
Heat shrinkable sleeves are available in many different colours, and can be made from many different materials. The most popular colours are clear – for use when the wire that is being covered has markings on it, red, green, yellow, and green/yellow. There are some companies which produce UV light reactive heat shrinkable sleeves for the enthusiast market.
Heat shrinkable sleeves are good insulators. They are also flexible, durable, and scratch resistant. Consumer grade heat shrinkable sleeves are durable enough to withstand light outdoor use, but for applications where the sleeves can expect to be exposed to very high temperatures, a more specialist product should be used.
If the sleeve is likely to be exposed to hazardous chemicals, then a fluoropolymer such as PTFE, FEP, or Viton should be used. The appropriate material for high temperature applications is Polyvinylidene Fluoride (PVDF). Conversely, for low temperature applications, Neoprene is a good choice.
Heat shrinkable materials are also available in “layflat” form. These are laid flat and can then be heated to shrink around the product which is being protected. The layflat heat shrinkable products are popular in the radio controlled vehicle market, where there are lots of open wires, connectors, and batteries that need protected, and standard heat shrinkable tubes may not meet the unusual size requirements, or fit in the cramped spaces.
Heat shrinkable sleeves can be purchased from most good electronics components catalogues, and consumer grade heat shrinkable sleeves are easily found on online auction sites such as ebay.