Understanding Shrinkback

by | May 3, 2023

Understanding Shrinkback

by | May 3, 2023

What exactly is shrinkback?

Whenever the insulation of a cable slide its way back from the termination connection or splice, shrinkback happens. When sliding away, it expands the length among the insulation’s tip and the termination connection or splice.

Understanding Shrinkback

Wire shorts are more likely to occur when there is insulation shrinkback. In addition, it may damage the barrier of protection, a seal, that the insulation as well as the jacket are meant to offer. We’re aware that these are serious issues that need to be avoided, which is why we ask; what exactly is the shrinkback of insulation, as well as, how could I avoid it from occurring?

An area of the conductor is unintentionally revealed when the insulating gap is enlarged. Consequently, the threat of their being a short is greater and the barrier of protection may be damaged, allowing for liquids and debris to penetrate the inside of the cables. This harm will be of high expense in not only the financial aspect but in time as well.

What exactly brings about insulation shrinkback?

Mechanical load and pressure from the production phase leads to shrinkback. The insulation material may expand if the material itself is emitted at even the most subtle speed. The insulation is bound to spontaneously shrink back to original length after the cable has been trimmed to length if friction is insufficient to maintain its position around conductors. Shrinkback tends to happen quicker when exposed to an elevated temperature as well as broad levels of temperatures.

Every cable is capable of experiencing shrinkback, though it is essential to keep in mind that PTFE-insulated cables have a higher susceptibility to experiencing it. Although PTFE is a nonstick substance, a special glue is utilized to secure the insulation to conductors throughout the production phase. Following then, that the special glue may continue to be dry and separate under physical strain.

Lower gauges, notably anything equal to or thinner than 24 gauge, that contains stranding anything equal to or less than 7, have been demonstrated to be more prone to shrinkback. The insulation has very little surface area to grasp since the stranding is so thin, which results in extremely low pressure for the jacket  retention.

Shrinkback, how can it be avoided?

Despite the fact that shrinkback appears to be inevitable, a number of actions exist to lessen its impact. One, while in the process of termination or splicing of the wires, one can pick components/substances that are not as prone to undergoing shrinkback as well as employing a crimp that supports insulation. One may also look into the shrinkback tests and specifications created by the not only the ICEA but also ANSI, and then mentioning your need for the cable to be shrinkback-free when ordering cable.

To avoid the disintegration of the insulation bonding, it is crucial to not overwork the wire or cable when processing it. Z-Tronix employs the following procedures to lessen the possibility of shrinkback brought on by excessive handling:

  • It is best that the reel used to store and transport wire and cable, utilizes the biggest cores to prevent wire from excessively bending.
  • Avoid tightening the payout reels more than necessary. Get the right tension by keeping them snug, but not so tight that they drag or strain the wire or cable.
  • Reduce the frequency of the wire or cable having to travel over or through guide pulleys, eyelets, counter wheels and anything of that sort.
  • Employ the highest sized bend radius whenever applicable. The amount of adhesion is reduced dramatically with smaller and longer bending.
  • Reduce or eradicate pressure placed on the wire or cable as it between not only drive wheels and belts but counters as well.
  • Limit the amount of times that capstans or de-reelers are passed.

The ideal strategy to combat PTFE shrinkback is to adhere to the straightforward procedures mentioned above. These will aid in preventing the insulation from being stretched and losing its bond to the stranding. Use this information to protect the wire or cable from the risk of shrinkback in your next wire/cable related project. Selecting a wire or cable that is capable of enduring a prolonged period in the application means looking for ones that will not have issues like these.

Although Z-Tronix Inc. adheres to the recommended procedures to reduce or eradicate shrinkback to the greatest extent, there is no assurance that it will ever be completely eradicated. The outcomes might differ in every reel itself.