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Hot tips for perfect results with heat shrink sleeves

Perfect environmental seals on HV cable shoes

The variety of heat shrink tubing is as diverse as the range of applications. Whether you use it to insulate cables, wires and joints, to provide additional mechanical and environmental protection, or just to colour code them, there are a variety of basic parameters that are decisive for the success of the final application.

Shrink ratio

How much the sleeve shrinks, i.e. the expanded, supplied diameter in relation to the recovered, shrunk diameter, is indicated by the shrink ratio. Ratios can vary from 2:1 to 6:1. The higher the ratio, the greater the range of applications the tubing can cover. As a result, fewer shrink tubing sizes are usually required.

Diameter

When selecting the tubing size, allow a minimum shrinkage of 20% and a maximum of 80% shrinkage. Beware: heat shrinkable tubing also shrinks in length, not just in diameter.

  • Need help with the maths? If you are not sure which sleeve will fit your application, simply enter the required dimensions into the HellermannTyton online heat shrink calculator and it will suggest the right size

MA47 heat shrink tubing showing supplied and recovered diameters

Wall thickness

In general, a distinction is made between thin-, medium- and thick-walled heat-shrinkable tubing. The variants with an inner adhesive are called "double-walled" tubing. The material thickness is generally stated in mm after complete shrinkage. "Nominal" refers to dimensions without any tolerances.

Temperature

The shrink temperature and the operating temperature vary depending on the individual  properties of each tubing - especially its fire safety performance. Do check the technical specs of each heat shrink product carefully against your application requirements.

Hot tips for perfect heat shrinking

  • Safety first! Always make sure that the workplace is well ventilated and that you wear personal protective equipment such as heatproof gloves and goggles. Use a heat gun that has a secure stand on the workbench so that you can work on the shrink application with both hands.
  • Tubing also shrinks lengthwise, which means it gets shorter overall as it shrinks. You should take this shrinkage rate into account when cutting sections.
  • When cutting heat shrink tubing to the desired length, take special care to cut the ends smoothly. Poorly cut and irregular ends can cause heat shrink tubing to tear during shrinking.
  • If the object to be wrapped is heat conductive, be sure to preheat the object to avoid "cold spots" or "cold marks". This will ensure a tight and smooth fit of the heat shrink tubing.
  • Start the shrinking process in the middle of the hose and then gradually move to one end and then again from the middle to the opposite end. This way you avoid trapping air under the tubing.

Check out Barry and Mark's YouTube playlist for more heat shrink tips and tricks from the experts:

From coloured and transparent heat-shrinkable sleeves, adhesive-lined tubing, rolls in handy dispenser boxes, to pre-cut lengths in kits and end caps, HellermannTyton offers a comprehensive range of products in various sizes.

See an overview here in the RS Components shop.

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