How Does Heat Shrink Tubing Work?

How Does Heat Shrink Tubing Work?
Loading... 5 min read
How Does Heat Shrink Tubing Work?

Heat shrink tubing is a shrinkable plastic used to insulate wires, providing abrasion resistance and environmental protection for stranded and solid wire conductors, connections, joints and terminals. With varying uses, heat shrink tubing is integral to protect and manage cabling systems.

Used to repair the insulation of electrical wires or create cable entry seals, and offer environmental sealing protection, heat shrink tubing is ordinarily made of polyolefin (a plastic polymer) which shrinks radially not longitudinally to between one-half and one-sixth of its diameter when heated.

Manufactured in a multitude of varieties and chemical make-ups, heat shrink tubing comes in varying compositions and sizes for broad application use. From almost microscopically thin wall tubing to rigid, heavy-wall tubing, each variant has a precise design and chemical adhesives to meet a range of demands.

The Different Types of Heat Shrink Tubing

Available in a variety of colours, used to colour code electrical and data wiring, commercial heat shrink tubing grew to prominence in the 1990’s and into the early twenty-first century having been used for modifying computers, game console chassis and wholesale cable labelling in commercial environments.

Additionally, heat shrink tubing has been increasingly employed to keep the hard drive cavity of a computer safe and tidy. Responding to demand, manufacturers began producing heat shrink tubing in luminous and UV reflective colours for easy identification in low light settings.

Speciality heat shrink tubing called solder sleeves feature solder inside the heat shrink tubing. This allows a heat source to electrically join the two wires by melting the solder and simultaneously insulate the junction with the tubing. Also, heat shrink end caps which are designed to be closed at one end are used to insulate the exposed cut end of insulated wires.

How Heat Shrink Tubing Works

To use heat shrink tubing all you need to do is to fit an unshrunk tube down a wire until it covers the joint or appropriate place on the wire. If the tubing is too snug to the sheath of the wire, a silicone lubricant can be applied to help it slide down the wire with ease.

Once in place the tubing is then shrunk to wrap tightly around the joint by heating using a hot air gun or alternative source of hot gas flow. Convenient but less consistent methods for shrinking include applying a soldering iron close to the heat shrink without touching it. However, this method requires care. Should the soldering iron directly touch the heat shrink it will burn through the material, burning through the heat shrink and occasionally piercing the sheath of the cable. If overheated, heat shrink can melt, scorch or even catch fire.

When you heat the plastic the tubing contracts between half and one-sixth the size of its original diameter depending on the composition of the heat shrink. This provides a snug fit to irregularly shaped wires and joint aspects.

A longitudinal shrinking, usually unwanted and less than the narrowing which, according to accepted statistics is just 6%. Some types of heat shrink contain a layer of thermoplastic adhesive on the inside which provides a seamless seal and improved adhesion. Other materials rely on the friction between the closely conforming materials.

Tubing provides good electrical insulation, protection against dust, solvents and other foreign materials in addition to sound mechanical strain relief. The snug fit holds the heat shrink in place. It’s both durable and effective for a range of applicational uses. Moreover, heat shrink tubing is sometimes sold in pre-cut lengths with a solder bob at the centre. This configuration is specified by Daimler-Benz and is used for automotive and electrical repairs.

The Popularity of Polyolefin Tubing

One of the most popular options of Both flame retardant and with good chemical, electrical and physical properties, polyolefin tubing is UL recognised and viewed as a reliable all-purpose heat shrink product.

Polyolefin tubing is available in a range of different sizes and has myriad of application uses. Occasionally referred to as automotive heat shrink tubing, it’s considered to be a good option for automotive application.

However, before you decide on a specific heat shrink tubing, it’s wise to consider what you need it for. Just because polyolefin tubing is sought-after in the automotive sector, it doesn’t automatically mean that its right for your purpose. If you’re in any doubt as to the right solution for you, contact Hilltop Products – we’d be happy to advise you.

How to Choose the Right Heat Shrink Tubing Size

To choose the right heat shrink tubing there’s just one primary consideration – the size. Take measurements using a calliper or ruler of the diameter of the smallest and largest aspects of what you’ll be covering with heat shrink.

Remember too that you’ll need to account for the degree in shrinkage so if any heat shrink is already excessively tight against a cable, for example, it may be too small. A heat shrink tube that’s already too small is likely to split when heat is applied to it. It’s generally advised that heat shrink tubing should be between twenty to thirty percent larger than the largest diameter measurement of your cable.

There’s another factor that you shouldn’t neglect – the shrink ratio. If it’s too big then it’s likely that the tubing won’t fit snugly. Too small and, as previously mentioned, the tubing will likely split when heat is applied to it.

Also, don’t forget to order a little more heat shrink tubing than you believe you’ll need, after all heat shrink tubing will by its very nature and purpose, shrink.

The Takeaway

You may not have ever thought much about it before, but heat shrink tubing is used in abundance for a wealth of purposes. It’s a simple yet for easy identification, cover exposed wiring and repair and insulate aspects of exposed wire.

If you’d like to find out if heat shrink tubing is the ideal solution for you, ask any questions, or learn more about diameter shrinkage, get in touch with Hilltop Products today.