A Full Guide To Heat Shrink Tubing For Wire And Cable
A heat-shrink tubing, or heat-shrink tape, or heatshrink, is a plastic sleeve applied over the electrical cable's sensitive components, such as cable terminations, cable splicing, and places where the wires connect.
The name heat-shrink tubing comes from the fact that the tubing shrinks once the heat is applied to it to approximately 50 percent of its diameter (depending on the type of material used). It was invented in California in the 1960s by a company that dealt with chemical innovations for engineering. Usually, the heat is applied using a special heat gun. As a result of this form-fitting process, you get cable insulation that is formed on the spot and perfectly fits the shape of the cable.
How is Heat-Shrink Tubing Achieved?
Heatshrink is a complicated process that is achieved through extrusion. It starts with making the preview tube extracted from the raw materials. Afterward, it is crosslinked and heated by the customer to reach the shape of the electrical cable upon which it is applied. As for the heat-shrink, it is durable and long-lasting.
Heat-shrink tubes available on the market follow UL flame-retardance tests, such as VW-1. They also follow their standards, such as Standard Specifications for Crosslinked and Noncrosslinked Poly(Vinyl Chloride) Heat-Shrinkable Tubing for Electrical Insulation, known under ASTM D3150-00.
Purposes Of Heat-Shrink Tapes
Heat-shrink tape is a cable insulator, albeit different from the insulation or the jacket, as it is not part of the electrical cable upon manufacturing; it can only be added afterward.
Aside from working as an insulator, heat-shrink tubing is the way to have additional environmental or mechanical protection for the cable.
Heat-shrink tubing differs from other custom insulators and jackets that are added to cables after the manufacturing process. The reason for this is that due to the physics of the heat-shrink tape, it can fit the exact dimensions of the electrical cable.
The goals of using heat-shrink tubing boil down to the following ways of protecting cables and expanding their lifespan:
- Insulating the cable
- Protecting the cable from the impact and the environment, including dust, moisture, sharp objects, abrasion, mechanical strains, etc.
- Protecting the cable from extreme heat in special applications like aircraft and military.
- Reducing the levels of mechanical stress placed on cables
- Bundling the cables together to use them for a specific goal
- Ensuring safe cable harnessing
- Marking of cables for particular purposes
- Repairing the existing insulation of the cable
Heat-Shrink Tubing vs. Electrical Tape: A Comparison
Electrical tape is often used for instant fixes of insulation materials on the spot because it is cheap, easy to apply, and readily available on the site almost everywhere, from homes to warehouses.
While good enough for instant fixes, electrical tape is a temporary, fragile solution that does not do well with many types of environmental impact.
Types Of Heat-Shrink Tubing And Their Applications
There are many types of heatshrink on the market, all made of different materials. The choice depends on the exact application and your budget. Different types of heatshrinking are different. Some are extremely thin, while others have sturdy, rigid construction. Most of the existing materials are waterproof. Here are the common types of heat-shrinking tapes:
- Polyolefin is the most common type of heat-shrinking. It is flexible, shrinks fast, and is available in a wide range of colors, making color marking convenient. However, it has poor resistance to UV, with the exception of the black tube. Polyolefin is an excellent choice for most common applications, except for outdoor ones.
- PVC is the cheapest variation of the heat-shrink. It is a so-called low-shrink variation, only able to shrink to about half of its size. Its temperature range is limited, but it can manage a reasonable degree of flexibility. Color-coding range for PVC is genuinely limitless. A PVC heat-shrink is best used when you need to save money, and the temperatures the cable will be affected by are not high.
- PTFE, or Teflon, has the best resistance to mechanical impact and chemicals from the available heat-shrink tapes.
- Silicon Rubber is flexible, abrasion-resistant, and with a good temperature range.
- Elastomer is very flexible, and resistant to abrasion and chemicals. It shines in applications where these characteristics are a must.
- FEP is a relatively inexpensive option perfect for outdoor use as it is UV-resistant, good in both hot and cold degrees, and does well with chemicals.
- PVDF is an expensive industrial heat-shrink tubing meant for high temp applications.
How Long Does Heat-Shrink Tape Last?
Heat-shrink tape is usually designed to be permanent as long as it is high-quality and the process of doing it is correct. Select the material that fits your applications to ensure that the heatshrink sleeve will be a permanent solution. The tube has to have an appropriate shrinking ratio, diameter, length, and thickness.
The usual size of the tube should be 20-30% larger than the broadest part of the cable, while also considering the shrinking ratio and calculating the final result based on it.