Overview of heat shrinkable cable accessories

Heat shrinkable cable accessories are tubes that shrink when heated to securely insulate and protect cable joints, terminations and connections. They are made of thermoplastic materials that can shrink up to 1/2 of their diameter when heated.

The most common types for Heat shrinkable cable accessories are heat shrink tubing and heat shrink end caps. Heat shrink tubing is used to insulate cables and splices, while end caps are used to seal the ends of cables and wires. Heat shrinkable cable accessories provide mechanical protection, electrical insulation, environmental sealing and strain relief. They create a tight fit over the components and cables as they shrink which protects from moisture, abrasion, chemicals, etc.

The common materials used for heat shrinkable cable accessories are polyolefin, polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET) and Kynar. Each has different shrink ratio, temperature tolerance and chemical resistance properties suitable for various applications.

Heat shrink products come with different shrink ratios like 2:1, 3:1 and 4:1. A 2:1 ratio will shrink a tube down to half its diameter. Higher ratio allows higher degree of shrinkage. Heat is applied using a heat gun. The heat causes the thermoplastic material to retract, which creates a tight seal around the components and insulates the connections. The heat shrinkable cable accessories sizes range from 1/16 inch for small components to up to several inches for large cable jackets. Proper sizing is important to get good shrink results and fit.  

Heat shrink tubing is commonly used to insulate wire splices, terminate wires, repair cable jackets, and bundle wires together. It creates an insulating and protective covering. Heat shrink end caps can seal the cut ends of cables and wires. Wrap-around heat shrink sleeves can also be used to bundle multiple wires and cables together. Adhesive-lined heat shrink products have a hot-melt adhesive inner lining that melts as the tubing shrinks and seals around the components. This provides a Watertight seal and stronger grip. Non-adhesive lined tubing only provides insulation.

Different shrink ratios are suitable for different applications. A higher ratio 4:1 or 6:1 allows the tube to shrink to a quarter or sixth of its size and is good for creating tight seals in small areas. A lower 2:1 or 3:1 ratio is good for less shrinkage on larger components.The heating temperature depends on the material. Polyolefin tubes typically shrink at 90 to 135°C, while PTFE tubes can handle 200 to 260°C. Heat guns typically have different temperature settings for different purposes. Proper heating technique is important to get even and complete shrinkage.

Colored translucent or opaque heat shrink tubing can be used for color-coding wires. This allows for easier circuit identification and troubleshooting. Custom printed heat shrink tubes are also available for this purpose.Some heat shrink products meet various agency standards like UL, CSA, MIL and aerospace standards for different electrical insulation and flammability requirements. This is important for industrial and commercial uses.