Heat Shrinking: How Does it Protect Your Wires and Cables?

FACTS CHECKED BY  Jose George​

Electrical connections work smoothly if all the wires, cables, and other components are in place. Manufacturers use various techniques to secure the cables and wires. One of them is heat shrinking. However, due to the wide availability of their materials and their precise usage, there is a lot of confusion. Now, read on to understand the details and how to choose one suitable for your application.

How to strip wire fast
How to strip wire fast

What Is Heat Shrink Protection?

Heat shrink protection is a technique that helps in providing tight and complete insulation to the cables and wires. Heat shrink tubing is tubes of special materials that insulate wires and cables. All these materials have the property of shrinking radially rather than longitudinally. As a result, the length is shorter on heating.

You can use heat shrink tubing after the wiring is complete. After wiring, move the heat shrink tube to the connected wires and cables. Now, expose this tube to any heat source, be it an oven, hot gas, or a heat gun. Due to heat, the tube shrinks around the connection providing it extended protection. Several colors are available in this tubing so you can designate the wires at your convenience. 

Heat Shrink tubing serves various purposes, such as:

  • It offers electrical insulation to an exposed or damaged part of a wire
  • It provides protection against moisture, abrasion, dust, and chemicals
  • It relieves the strain of cables when held at tension
  • You can bundle wires into single units with this tubing
  • It allows easy identification of wires due to its availability in a wide range of colors.
heat shrink tubing for the protection of cable isolation

Image: heat shrink tubing for the protection of cable isolation

How Can You Use a Heat Shrink Tube Safely?

Heat shrink tubing provides an extra protective layer to wires and cables only if you use it with caution. Make sure that you observe basic safety rules so that there are no injuries and accidents. 

  • Firstly, choose the suitable size tubing with an appropriate shrink ratio. The tube should cover the wires and their components well before shrinking, ensuring they are tight to the cables and wires.
  • Secondly, ensure that if covered components tend to expand, the tubing must also have expandability. Compare the tubing diameter before and after shrinking and check its expandable capacity. Also, ensure that you apply the appropriate temperature so there are no uneven melts.
  • Thirdly, specialized appliances for applying heat like a heating gun or heat shrinking oven. Using such equipment ensures improved and precise heat application.
  • Lastly, moving the gun to and fro rather than keeping it in one place when using a heat gun. It will ensure correct heat applications and reduce the chances of tubing burns. Continue applying the heat until the tubing wrap becomes tightly secured.
heat shrink tubing in different colors

Image: heat shrink tubing in different colors

Common Heat-Shrink Materials

Heat shrink sleeves use a range of materials with different properties and strengths. 

Polyolefin tubing

It is a synthetic polymer with high chemical resistance and extreme heat. Due to these features, it is one of the most common materials for heat shrink sleeves.

PVC tubing

PVC stands for polyvinyl chloride, and it is also a popular material type due to its versatile nature and flat surface.

PTFE tubing

PTFE stands for polytetrafluoroethylene, and this is a synthetic compound that shows high chemical resistance. Further, it also has a small coefficient of friction so that substances slide from it quickly and easily; you may know it by the common brand name Teflon®.

FEP tubing

FEP is an excellent option in sealant applications as it has high resistance to chemical spillage, and FEP can shrink at a lower temperature than PTFE.

Elastomeric tubing

This tubing is well known for its flexible nature and its property of abrasion resistance. It also shows resistance to harmful liquids like hydraulic fluid and diesel. You can use them to protect cabling in different industrial applications.

PVDF tubing

PVDF stands for polyvinylidene Fluoride and shows high flame, corrosion, and fuel resistance. The good part is that this heat shrink material is robust and does not perforate easily.

Silicone tubing

Silicone tubing is highly flexible and resilient on exposure to very low or very high temperatures. You can use them to protect fiber optic cables and insulate heating elements. As silicone can bear sterilization conditions, you can use them in medical applications.

Viton tubing

Viton tubing comprises Fluoroelastomer, which is a synthetic rubber. This tubing material has high-temperature resistance and is flexible at lower temperatures. In addition, It also has the property of sealing against different kinds of lubricants, oils, and fuels.

Different Heat Shrink Sleeve Types

Heat shrink tubing is of two types. And the kind of tubing you choose depends on the level of protection your application demands.

Thin or single wall tubing

Single wall tubing offers excellent cable insulation and strain relief, abrasion resistance, and protection against mechanical damage. This tubing has consistent dimensions and reliable physical properties.

Dual or double-wall tubing

On the other hand, double-wall tubing is an excellent choice for heat-Shrink tubing applications requiring corrosion-resistive materials and sealing. The double-wall tubing has an additional layer of adhesive, offering a protective seal that does not allow moisture to penetrate.

heat shrink sleeve

Image: heat shrink sleeve

Heat Shrink accessories

The heat shrink tubing needs several supportive fittings, making tubing applications challenging to complete.

Heat Shrink Sleeve Connectors

These splices or connectors are tubing structures that help join cables or connect them to wall outlets. Connectors usually comprise polyolefin material having a double-wall design. The first layer is an outer layer that melts in its place to form a strong and water-resistive seal.

Heat Shrink Wrap

It is a modified form of the Heat Shrink Sleeve, which you can wrap around cables during splicing operations and repairs. With a shrink ratio of 3:1, it forms a firm seal that protects against chemicals, moisture, and fungal damage.

Heat Shrink Sleeve Tape

Working on similar principles as tubing, you can use this tape and tubing to insulate enclosures and seals.

Tips to Pick the Right Size of Heat Shrink Sleeve

Getting the proper advantage of heat shrink tubing requires using tubing of the right size and length. Here are some tips which help you choose the right heat shrink tubing size.

First, measure the broadest section of the wires, cables, and components to which you will apply tubing.

Now, select a tube about 20-30% more in size. For the right size of heat shrink tubing, you must know:

  1. You must know the shrink ratio of the tubing. If the shrink ratio is 2:1, the sleeve will shrink to half its original size on heating, while a ratio of 3:1 means the tubing will shrink one-third of its size on heating.
  2. You must know the thickness of the tubing walls, which are in millimeters and inches.
  3. Further, you should know the inside diameter of the heat-shrink tubing after shrinkage to the expanded inside diameter before shrinkage (original size). You can see the expanded diameter on the tubing label.

Finally, consider the tubing’s length. On heating, the tubing length decreases by 5-10%. Don’t forget to consider this shrinkage when you select the tubing length.

setting fire of heat shrinkable tube

Image: setting fire of heat shrinkable tube

Heat Shrink Certificates and Standards

UL224-2010: it specifies all the requirements for using round insulating heat shrink tubing made with polymers having elastic, heat-responding, and heat-setting characteristics.

SAE international AS23053: This standard specifies requirements for using an electrically insulated sleeve that can reduce to a preset size on heating. 

ASTM international D 2671: This standard specifies different tubing testing methods for electric cables.

ASTM D3150: These specifications apply to PVC heat shrink tubing when you are using it for electrical insulation.

Conclusion

Heat shrink protection is a rapid and simple technique for protecting your wires and cables. So, it is always good to have some tubing handy with you. However, it is equally essential to make the right choice suitable for your application. Cloom’s technical experts can help you in making the right choice in this regard. After analyzing, our team listens to your requirements and suggests the best heat shrink tubing. Call us today or email us your needs.

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